| Message ID | 20220124084708.683-1-thunder.leizhen@huawei.com |
|---|---|
| Headers | show |
| Series | support reserving crashkernel above 4G on arm64 kdump | expand |
On 1/24/22 2:47 AM, Zhen Lei wrote: > insert_resource() traverses the subtree layer by layer from the root node > until a proper location is found. Compared with request_resource(), the > parent node does not need to be determined in advance. > > In addition, move the insertion of node 'crashk_res' into function > reserve_crashkernel() to make the associated code close together. > > Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com> Acked-by: John Donnelly <john.p.donnelly@oracle.com> > --- > arch/arm64/kernel/setup.c | 17 +++-------------- > arch/arm64/mm/init.c | 1 + > 2 files changed, 4 insertions(+), 14 deletions(-) > > diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c > index f70573928f1bff0..a81efcc359e4e78 100644 > --- a/arch/arm64/kernel/setup.c > +++ b/arch/arm64/kernel/setup.c > @@ -225,6 +225,8 @@ static void __init request_standard_resources(void) > kernel_code.end = __pa_symbol(__init_begin - 1); > kernel_data.start = __pa_symbol(_sdata); > kernel_data.end = __pa_symbol(_end - 1); > + insert_resource(&iomem_resource, &kernel_code); > + insert_resource(&iomem_resource, &kernel_data); > > num_standard_resources = memblock.memory.cnt; > res_size = num_standard_resources * sizeof(*standard_resources); > @@ -246,20 +248,7 @@ static void __init request_standard_resources(void) > res->end = __pfn_to_phys(memblock_region_memory_end_pfn(region)) - 1; > } > > - request_resource(&iomem_resource, res); > - > - if (kernel_code.start >= res->start && > - kernel_code.end <= res->end) > - request_resource(res, &kernel_code); > - if (kernel_data.start >= res->start && > - kernel_data.end <= res->end) > - request_resource(res, &kernel_data); > -#ifdef CONFIG_KEXEC_CORE > - /* Userspace will find "Crash kernel" region in /proc/iomem. */ > - if (crashk_res.end && crashk_res.start >= res->start && > - crashk_res.end <= res->end) > - request_resource(res, &crashk_res); > -#endif > + insert_resource(&iomem_resource, res); > } > } > > diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c > index db63cc885771a52..90f276d46b93bc6 100644 > --- a/arch/arm64/mm/init.c > +++ b/arch/arm64/mm/init.c > @@ -109,6 +109,7 @@ static void __init reserve_crashkernel(void) > kmemleak_ignore_phys(crash_base); > crashk_res.start = crash_base; > crashk_res.end = crash_base + crash_size - 1; > + insert_resource(&iomem_resource, &crashk_res); > } > #else > static void __init reserve_crashkernel(void)
On 1/24/22 2:47 AM, Zhen Lei wrote: > From: Chen Zhou <chenzhou10@huawei.com> > > There are following issues in arm64 kdump: > 1. We use crashkernel=X to reserve crashkernel below 4G, which > will fail when there is no enough low memory. > 2. If reserving crashkernel above 4G, in this case, crash dump > kernel will boot failure because there is no low memory available > for allocation. > > To solve these issues, change the behavior of crashkernel=X and > introduce crashkernel=X,[high,low]. crashkernel=X tries low allocation > in DMA zone, and fall back to high allocation if it fails. > We can also use "crashkernel=X,high" to select a region above DMA zone, > which also tries to allocate at least 256M in DMA zone automatically. > "crashkernel=Y,low" can be used to allocate specified size low memory. > > Signed-off-by: Chen Zhou <chenzhou10@huawei.com> > Co-developed-by: Zhen Lei <thunder.leizhen@huawei.com> > Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com> Acked-by: John Donnelly <john.p.donnelly@oracle.com> > --- > arch/arm64/kernel/machine_kexec.c | 9 +++- > arch/arm64/kernel/machine_kexec_file.c | 12 ++++- > arch/arm64/mm/init.c | 68 ++++++++++++++++++++++++-- > 3 files changed, 81 insertions(+), 8 deletions(-) > > diff --git a/arch/arm64/kernel/machine_kexec.c b/arch/arm64/kernel/machine_kexec.c > index e16b248699d5c3c..19c2d487cb08feb 100644 > --- a/arch/arm64/kernel/machine_kexec.c > +++ b/arch/arm64/kernel/machine_kexec.c > @@ -329,8 +329,13 @@ bool crash_is_nosave(unsigned long pfn) > > /* in reserved memory? */ > addr = __pfn_to_phys(pfn); > - if ((addr < crashk_res.start) || (crashk_res.end < addr)) > - return false; > + if ((addr < crashk_res.start) || (crashk_res.end < addr)) { > + if (!crashk_low_res.end) > + return false; > + > + if ((addr < crashk_low_res.start) || (crashk_low_res.end < addr)) > + return false; > + } > > if (!kexec_crash_image) > return true; > diff --git a/arch/arm64/kernel/machine_kexec_file.c b/arch/arm64/kernel/machine_kexec_file.c > index 59c648d51848886..889951291cc0f9c 100644 > --- a/arch/arm64/kernel/machine_kexec_file.c > +++ b/arch/arm64/kernel/machine_kexec_file.c > @@ -65,10 +65,18 @@ static int prepare_elf_headers(void **addr, unsigned long *sz) > > /* Exclude crashkernel region */ > ret = crash_exclude_mem_range(cmem, crashk_res.start, crashk_res.end); > + if (ret) > + goto out; > + > + if (crashk_low_res.end) { > + ret = crash_exclude_mem_range(cmem, crashk_low_res.start, crashk_low_res.end); > + if (ret) > + goto out; > + } > > - if (!ret) > - ret = crash_prepare_elf64_headers(cmem, true, addr, sz); > + ret = crash_prepare_elf64_headers(cmem, true, addr, sz); > > +out: > kfree(cmem); > return ret; > } > diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c > index 6c653a2c7cff052..a5d43feac0d7d96 100644 > --- a/arch/arm64/mm/init.c > +++ b/arch/arm64/mm/init.c > @@ -71,6 +71,30 @@ phys_addr_t arm64_dma_phys_limit __ro_after_init; > #define CRASH_ADDR_LOW_MAX arm64_dma_phys_limit > #define CRASH_ADDR_HIGH_MAX MEMBLOCK_ALLOC_ACCESSIBLE > > +static int __init reserve_crashkernel_low(unsigned long long low_size) > +{ > + unsigned long long low_base; > + > + /* passed with crashkernel=0,low ? */ > + if (!low_size) > + return 0; > + > + low_base = memblock_phys_alloc_range(low_size, CRASH_ALIGN, 0, CRASH_ADDR_LOW_MAX); > + if (!low_base) { > + pr_err("cannot allocate crashkernel low memory (size:0x%llx).\n", low_size); > + return -ENOMEM; > + } > + > + pr_info("crashkernel low memory reserved: 0x%llx - 0x%llx (%lld MB)\n", > + low_base, low_base + low_size, low_size >> 20); > + > + crashk_low_res.start = low_base; > + crashk_low_res.end = low_base + low_size - 1; > + insert_resource(&iomem_resource, &crashk_low_res); > + > + return 0; > +} > + > /* > * reserve_crashkernel() - reserves memory for crash kernel > * > @@ -81,29 +105,62 @@ phys_addr_t arm64_dma_phys_limit __ro_after_init; > static void __init reserve_crashkernel(void) > { > unsigned long long crash_base, crash_size; > + unsigned long long crash_low_size = SZ_256M; > unsigned long long crash_max = CRASH_ADDR_LOW_MAX; > int ret; > + bool fixed_base; > + char *cmdline = boot_command_line; > > - ret = parse_crashkernel(boot_command_line, memblock_phys_mem_size(), > + /* crashkernel=X[@offset] */ > + ret = parse_crashkernel(cmdline, memblock_phys_mem_size(), > &crash_size, &crash_base); > - /* no crashkernel= or invalid value specified */ > - if (ret || !crash_size) > - return; > + if (ret || !crash_size) { > + unsigned long long low_size; > > + /* crashkernel=X,high */ > + ret = parse_crashkernel_high(cmdline, 0, &crash_size, &crash_base); > + if (ret || !crash_size) > + return; > + > + /* crashkernel=X,low */ > + ret = parse_crashkernel_low(cmdline, 0, &low_size, &crash_base); > + if (!ret) > + crash_low_size = low_size; > + > + crash_max = CRASH_ADDR_HIGH_MAX; > + } > + > + fixed_base = !!crash_base; > crash_size = PAGE_ALIGN(crash_size); > > /* User specifies base address explicitly. */ > if (crash_base) > crash_max = crash_base + crash_size; > > +retry: > crash_base = memblock_phys_alloc_range(crash_size, CRASH_ALIGN, > crash_base, crash_max); > if (!crash_base) { > + /* > + * Attempt to fully allocate low memory failed, fall back > + * to high memory, the minimum required low memory will be > + * reserved later. > + */ > + if (!fixed_base && (crash_max == CRASH_ADDR_LOW_MAX)) { > + crash_max = CRASH_ADDR_HIGH_MAX; > + goto retry; > + } > + > pr_warn("cannot allocate crashkernel (size:0x%llx)\n", > crash_size); > return; > } > > + if (crash_base >= SZ_4G && reserve_crashkernel_low(crash_low_size)) { > + memblock_phys_free(crash_base, crash_size); > + return; > + } > + > pr_info("crashkernel reserved: 0x%016llx - 0x%016llx (%lld MB)\n", > crash_base, crash_base + crash_size, crash_size >> 20); > > @@ -112,6 +169,9 @@ static void __init reserve_crashkernel(void) > * map. Inform kmemleak so that it won't try to access it. > */ > kmemleak_ignore_phys(crash_base); > + if (crashk_low_res.end) > + kmemleak_ignore_phys(crashk_low_res.start); > + > crashk_res.start = crash_base; > crashk_res.end = crash_base + crash_size - 1; > insert_resource(&iomem_resource, &crashk_res);
On 1/24/22 2:47 AM, Zhen Lei wrote: > From: Chen Zhou <chenzhou10@huawei.com> > > For arm64, the behavior of crashkernel=X has been changed, which > tries low allocation in DMA zone and fall back to high allocation > if it fails. > > We can also use "crashkernel=X,high" to select a high region above > DMA zone, which also tries to allocate at least 256M low memory in > DMA zone automatically and "crashkernel=Y,low" can be used to allocate > specified size low memory. > > So update the Documentation. > > Signed-off-by: Chen Zhou <chenzhou10@huawei.com> > Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com> Acked-by: John Donnelly <john.p.donnelly@oracle.com> > --- > Documentation/admin-guide/kdump/kdump.rst | 11 +++++++++-- > Documentation/admin-guide/kernel-parameters.txt | 11 +++++++++-- > 2 files changed, 18 insertions(+), 4 deletions(-) > > diff --git a/Documentation/admin-guide/kdump/kdump.rst b/Documentation/admin-guide/kdump/kdump.rst > index cb30ca3df27c9b2..d4c287044be0c70 100644 > --- a/Documentation/admin-guide/kdump/kdump.rst > +++ b/Documentation/admin-guide/kdump/kdump.rst > @@ -361,8 +361,15 @@ Boot into System Kernel > kernel will automatically locate the crash kernel image within the > first 512MB of RAM if X is not given. > > - On arm64, use "crashkernel=Y[@X]". Note that the start address of > - the kernel, X if explicitly specified, must be aligned to 2MiB (0x200000). > + On arm64, use "crashkernel=X" to try low allocation in DMA zone and > + fall back to high allocation if it fails. > + We can also use "crashkernel=X,high" to select a high region above > + DMA zone, which also tries to allocate at least 256M low memory in > + DMA zone automatically. > + "crashkernel=Y,low" can be used to allocate specified size low memory. > + Use "crashkernel=Y@X" if you really have to reserve memory from > + specified start address X. Note that the start address of the kernel, > + X if explicitly specified, must be aligned to 2MiB (0x200000). > > Load the Dump-capture Kernel > ============================ > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt > index f5a27f067db9ed9..65780c2ca830be0 100644 > --- a/Documentation/admin-guide/kernel-parameters.txt > +++ b/Documentation/admin-guide/kernel-parameters.txt > @@ -792,6 +792,9 @@ > [KNL, X86-64] Select a region under 4G first, and > fall back to reserve region above 4G when '@offset' > hasn't been specified. > + [KNL, ARM64] Try low allocation in DMA zone and fall back > + to high allocation if it fails when '@offset' hasn't been > + specified. > See Documentation/admin-guide/kdump/kdump.rst for further details. > > crashkernel=range1:size1[,range2:size2,...][@offset] > @@ -808,6 +811,8 @@ > Otherwise memory region will be allocated below 4G, if > available. > It will be ignored if crashkernel=X is specified. > + [KNL, ARM64] range in high memory. > + Allow kernel to allocate physical memory region from top. > crashkernel=size[KMG],low > [KNL, X86-64] range under 4G. When crashkernel=X,high > is passed, kernel could allocate physical memory region > @@ -816,13 +821,15 @@ > requires at least 64M+32K low memory, also enough extra > low memory is needed to make sure DMA buffers for 32-bit > devices won't run out. Kernel would try to allocate at > - at least 256M below 4G automatically. > + least 256M below 4G automatically. > This one let user to specify own low range under 4G > for second kernel instead. > 0: to disable low allocation. > It will be ignored when crashkernel=X,high is not used > or memory reserved is below 4G. > - > + [KNL, ARM64] range in low memory. > + This one let user to specify a low range in DMA zone for > + crash dump kernel. > cryptomgr.notests > [KNL] Disable crypto self-tests >
On 02/07/22 at 12:04pm, Leizhen (ThunderTown) wrote: > Hi everybody: > Can someone take a moment to review these patches? Maybe I should just try > making generic. This patch series seems to have gone back to square one, > discarding some of the valuable comments that were made in the middle. But the > only benefit of make generic is to avoid code duplication, a lot of adaptation > is needed. I think Borislav Petkov's suggestion is good, too. I am checking this version. I have got a arm64 machine, will give it a shot. About deduplicating the copied code, it's good to have comparing with having an important feature in a certian ARCH. Add Philipp to CC since he investigates the deduplicating. > > These patches are taking too long. Maybe no one wants to look through history > anymore. So I'm putting together some of the most central observations of > "make generic" as follows: > Mike Rapoport: > This very reminds what x86 does. Any chance some of the code can be reused > rather than duplicated? > https://lkml.org/lkml/2019/4/4/1225 > > I think it would be better to have CONFIG_ARCH_WANT_RESERVE_CRASH_KERNEL > in arch/Kconfig and select this by X86 and ARM64. > https://lkml.org/lkml/2020/11/12/224 > > Ingo Molnar: > No objections for this to be merged via the ARM tree, as long as x86 > functionality is kept intact. > https://lkml.org/lkml/2019/4/10/109 > > I.e. Ack, but only if it doesn't break anything. :-) > https://lkml.org/lkml/2019/4/12/66 > > Dave Young: > Other than the comments from James, can you move the function into > kernel/crash_core.c, we already have some functions moved there for > sharing. > https://lkml.org/lkml/2019/6/12/248 > > Catalin Marinas: > Except for the threshold to keep zone ZONE_DMA memory, > reserve_crashkernel() looks very close to the x86 version. Shall we try > to make this generic as well? > https://lkml.org/lkml/2020/9/2/917 > > Borislav Petkov: > Why insert_resource() is relevant only to x86? > --> I think this means "Why does arm64 not use insert_resource()?" > https://lkml.org/lkml/2021/12/23/480 > > This is exactly why I say that making those functions generic and shared > might not be such a good idea, after all, because then you'd have to > sprinkle around arch-specific stuff. > https://lkml.org/lkml/2021/12/23/480 > > What I suggested and what would be real clean is if the arches would > simply call a *single* > parse_crashkernel() > function and when that one returns, *all* crashkernel= options would > have been parsed properly, low, high, middle crashkernel, whatever... > and the caller would know what crash kernel needs to be allocated. > https://lkml.org/lkml/2021/12/28/305 > > ------ > James Morse: > We can then describe it via a different string in /proc/iomem, something > like "Crash kernel (low)". > https://lkml.org/lkml/2019/6/5/670 > --> The suggestion looks out of date. See Borislav Petkov's comments: > --> 157752d84f5d ("kexec: use Crash kernel for Crash kernel low") > --> https://lkml.org/lkml/2021/12/23/480 > > > On 2022/1/24 16:47, Zhen Lei wrote: > > There are following issues in arm64 kdump: > > 1. We use crashkernel=X to reserve crashkernel below 4G, which > > will fail when there is no enough low memory. > > 2. If reserving crashkernel above 4G, in this case, crash dump > > kernel will boot failure because there is no low memory available > > for allocation. > > > > To solve these issues, change the behavior of crashkernel=X. > > crashkernel=X tries low allocation in DMA zone and fall back to high > > allocation if it fails. > > > > We can also use "crashkernel=X,high" to select a high region above > > DMA zone, which also tries to allocate at least 256M low memory in > > DMA zone automatically and "crashkernel=Y,low" can be used to allocate > > specified size low memory. > > > > When reserving crashkernel in high memory, some low memory is reserved > > for crash dump kernel devices. So there may be two regions reserved for > > crash dump kernel. > > In order to distinct from the high region and make no effect to the use > > of existing kexec-tools, rename the low region as "Crash kernel (low)", > > and pass the low region by reusing DT property > > "linux,usable-memory-range". We made the low memory region as the last > > range of "linux,usable-memory-range" to keep compatibility with existing > > user-space and older kdump kernels. > > > > Besides, we need to modify kexec-tools: > > arm64: support more than one crash kernel regions(see [1]) > > > > Another update is document about DT property 'linux,usable-memory-range': > > schemas: update 'linux,usable-memory-range' node schema(see [2]) > > > > > > Changes since [v19]: > > 1. Temporarily stop making reserve_crashkernel[_low]() generic. There are a > > lot of details need to be considered, which can take a long time. Because > > "make generic" does not add new functions and does not improve performance, > > maybe I should say it's just a cleanup. So by stripping it out and leaving > > it for other patches later, we can aggregate the changes to the main functions. > > 2. Use insert_resource() to replace request_resource(), this not only simplifies > > the code, but also reduces the differences between arm64 and x86 implementations. > > 3. As commit 157752d84f5d ("kexec: use Crash kernel for Crash kernel low") do for > > x86, we can also extend kexec-tools for arm64, and it's currently applied. See: > > https://www.spinics.net/lists/kexec/msg28284.html > > > > Thank you very much, Borislav Petkov, for so many valuable comments. > > > > > > > > Changes since [v17]: v17 --> v19 > > 1. Patch 0001-0004 > > Introduce generic parse_crashkernel_high_low() to bring the parsing of > > "crashkernel=X,high" and the parsing of "crashkernel=X,low" together, > > then use it instead of the call to parse_crashkernel_{high|low}(). Two > > confusing parameters of parse_crashkernel_{high|low}() are deleted. > > > > I previously sent these four patches separately: > > [1] https://lkml.org/lkml/2021/12/25/40 > > 2. Patch 0005-0009 > > Introduce generic reserve_crashkernel_mem[_low](), the implementation of > > these two functions is based on function reserve_crashkernel[_low]() in > > arch/x86/kernel/setup.c. There is no functional change for x86. > > 1) The check position of xen_pv_domain() does not change. > > 2) Still 1M alignment for crash kernel fixed region, when 'base' is specified. > > > > To avoid compilation problems on other architectures: patch 0004 moves > > the definition of global variable crashk[_low]_res from kexec_core.c to > > crash_core.c, and provide default definitions for all macros involved, a > > particular platform can redefine these macros to override the default > > values. > > 3. 0010, only one line of comment was changed. > > 4. 0011 > > 1) crashk_low_res may also a valid reserved memory, should be checked > > in crash_is_nosave(), see arch/arm64/kernel/machine_kexec. > > 2) Drop memblock_mark_nomap() for crashk_low_res, because of: > > 2687275a5843 arm64: Force NO_BLOCK_MAPPINGS if crashkernel reservation is required > > 3) Also call kmemleak_ignore_phys() for crashk_low_res, because of: > > 85f58eb18898 arm64: kdump: Skip kmemleak scan reserved memory for kdump > > 5. 0012, slightly rebased, because the following patch is applied in advance. > > https://git.kernel.org/pub/scm/linux/kernel/git/robh/linux.git/commit/?h=dt/linus&id=8347b41748c3019157312fbe7f8a6792ae396eb7 > > 6. 0013, no change. > > > > Others: > > 1. Discard add ARCH_WANT_RESERVE_CRASH_KERNEL > > 2. When allocating crash low memory, the start address still starts from 0. > > low_base = memblock_phys_alloc_range(low_size, CRASH_ALIGN, 0, CRASH_ADDR_LOW_MAX); > > 3. Discard change (1ULL << 32) to CRASH_ADDR_LOW_MAX. > > 4. Ensure the check position of xen_pv_domain() have no change. > > 5. Except patch 0010 and 0012, all "Tested-by", "Reviewed-by", "Acked-by" are removed. > > 6. Update description. > > > > > > > > Changes since [v16] > > - Because no functional changes in this version, so add > > "Tested-by: Dave Kleikamp <dave.kleikamp@oracle.com>" for patch 1-9 > > - Add "Reviewed-by: Rob Herring <robh@kernel.org>" for patch 8 > > - Update patch 9 based on the review comments of Rob Herring > > - As Catalin Marinas's suggestion, merge the implementation of > > ARCH_WANT_RESERVE_CRASH_KERNEL into patch 5. Ensure that the > > contents of X86 and ARM64 do not overlap, and reduce unnecessary > > temporary differences. > > > > Changes since [v15] > > - Aggregate the processing of "linux,usable-memory-range" into one function. > > Only patch 9-10 have been updated. > > > > Changes since [v14] > > - Recovering the requirement that the CrashKernel memory regions on X86 > > only requires 1 MiB alignment. > > - Combine patches 5 and 6 in v14 into one. The compilation warning fixed > > by patch 6 was introduced by patch 5 in v14. > > - As with crashk_res, crashk_low_res is also processed by > > crash_exclude_mem_range() in patch 7. > > - Due to commit b261dba2fdb2 ("arm64: kdump: Remove custom linux,usable-memory-range handling") > > has removed the architecture-specific code, extend the property "linux,usable-memory-range" > > in the platform-agnostic FDT core code. See patch 9. > > - Discard the x86 description update in the document, because the description > > has been updated by commit b1f4c363666c ("Documentation: kdump: update kdump guide"). > > - Change "arm64" to "ARM64" in Doc. > > > > > > Changes since [v13] > > - Rebased on top of 5.11-rc5. > > - Introduce config CONFIG_ARCH_WANT_RESERVE_CRASH_KERNEL. > > Since reserve_crashkernel[_low]() implementations are quite similar on > > other architectures, so have CONFIG_ARCH_WANT_RESERVE_CRASH_KERNEL in > > arch/Kconfig and select this by X86 and ARM64. > > - Some minor cleanup. > > > > Changes since [v12] > > - Rebased on top of 5.10-rc1. > > - Keep CRASH_ALIGN as 16M suggested by Dave. > > - Drop patch "kdump: add threshold for the required memory". > > - Add Tested-by from John. > > > > Changes since [v11] > > - Rebased on top of 5.9-rc4. > > - Make the function reserve_crashkernel() of x86 generic. > > Suggested by Catalin, make the function reserve_crashkernel() of x86 generic > > and arm64 use the generic version to reimplement crashkernel=X. > > > > Changes since [v10] > > - Reimplement crashkernel=X suggested by Catalin, Many thanks to Catalin. > > > > Changes since [v9] > > - Patch 1 add Acked-by from Dave. > > - Update patch 5 according to Dave's comments. > > - Update chosen schema. > > > > Changes since [v8] > > - Reuse DT property "linux,usable-memory-range". > > Suggested by Rob, reuse DT property "linux,usable-memory-range" to pass the low > > memory region. > > - Fix kdump broken with ZONE_DMA reintroduced. > > - Update chosen schema. > > > > Changes since [v7] > > - Move x86 CRASH_ALIGN to 2M > > Suggested by Dave and do some test, move x86 CRASH_ALIGN to 2M. > > - Update Documentation/devicetree/bindings/chosen.txt. > > Add corresponding documentation to Documentation/devicetree/bindings/chosen.txt > > suggested by Arnd. > > - Add Tested-by from Jhon and pk. > > > > Changes since [v6] > > - Fix build errors reported by kbuild test robot. > > > > Changes since [v5] > > - Move reserve_crashkernel_low() into kernel/crash_core.c. > > - Delete crashkernel=X,high. > > - Modify crashkernel=X,low. > > If crashkernel=X,low is specified simultaneously, reserve spcified size low > > memory for crash kdump kernel devices firstly and then reserve memory above 4G. > > In addition, rename crashk_low_res as "Crash kernel (low)" for arm64, and then > > pass to crash dump kernel by DT property "linux,low-memory-range". > > - Update Documentation/admin-guide/kdump/kdump.rst. > > > > Changes since [v4] > > - Reimplement memblock_cap_memory_ranges for multiple ranges by Mike. > > > > Changes since [v3] > > - Add memblock_cap_memory_ranges back for multiple ranges. > > - Fix some compiling warnings. > > > > Changes since [v2] > > - Split patch "arm64: kdump: support reserving crashkernel above 4G" as > > two. Put "move reserve_crashkernel_low() into kexec_core.c" in a separate > > patch. > > > > Changes since [v1]: > > - Move common reserve_crashkernel_low() code into kernel/kexec_core.c. > > - Remove memblock_cap_memory_ranges() i added in v1 and implement that > > in fdt_enforce_memory_region(). > > There are at most two crash kernel regions, for two crash kernel regions > > case, we cap the memory range [min(regs[*].start), max(regs[*].end)] > > and then remove the memory range in the middle. > > > > [1]: https://www.spinics.net/lists/kexec/msg28226.html > > [2]: https://github.com/robherring/dt-schema/pull/19 > > [v1]: https://lkml.org/lkml/2019/4/2/1174 > > [v2]: https://lkml.org/lkml/2019/4/9/86 > > [v3]: https://lkml.org/lkml/2019/4/9/306 > > [v4]: https://lkml.org/lkml/2019/4/15/273 > > [v5]: https://lkml.org/lkml/2019/5/6/1360 > > [v6]: https://lkml.org/lkml/2019/8/30/142 > > [v7]: https://lkml.org/lkml/2019/12/23/411 > > [v8]: https://lkml.org/lkml/2020/5/21/213 > > [v9]: https://lkml.org/lkml/2020/6/28/73 > > [v10]: https://lkml.org/lkml/2020/7/2/1443 > > [v11]: https://lkml.org/lkml/2020/8/1/150 > > [v12]: https://lkml.org/lkml/2020/9/7/1037 > > [v13]: https://lkml.org/lkml/2020/10/31/34 > > [v14]: https://lkml.org/lkml/2021/1/30/53 > > [v15]: https://lkml.org/lkml/2021/10/19/1405 > > [v16]: https://lkml.org/lkml/2021/11/23/435 > > [v17]: https://lkml.org/lkml/2021/12/10/38 > > [v18]: https://lkml.org/lkml/2021/12/22/424 > > [v19]: https://lkml.org/lkml/2021/12/28/203 > > > > > > Chen Zhou (4): > > arm64: kdump: introduce some macros for crash kernel reservation > > arm64: kdump: reimplement crashkernel=X > > of: fdt: Add memory for devices by DT property > > "linux,usable-memory-range" > > kdump: update Documentation about crashkernel > > > > Zhen Lei (1): > > arm64: Use insert_resource() to simplify code > > > > Documentation/admin-guide/kdump/kdump.rst | 11 ++- > > .../admin-guide/kernel-parameters.txt | 11 ++- > > arch/arm64/kernel/machine_kexec.c | 9 ++- > > arch/arm64/kernel/machine_kexec_file.c | 12 ++- > > arch/arm64/kernel/setup.c | 17 +--- > > arch/arm64/mm/init.c | 80 +++++++++++++++++-- > > drivers/of/fdt.c | 33 +++++--- > > 7 files changed, 134 insertions(+), 39 deletions(-) > > > > -- > Regards, > Zhen Lei >
On 2022/2/14 15:53, Leizhen (ThunderTown) wrote: > > > On 2022/2/14 11:52, Baoquan He wrote: >> On 01/24/22 at 04:47pm, Zhen Lei wrote: >> ...... >>> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c >>> index 6c653a2c7cff052..a5d43feac0d7d96 100644 >>> --- a/arch/arm64/mm/init.c >>> +++ b/arch/arm64/mm/init.c >>> @@ -71,6 +71,30 @@ phys_addr_t arm64_dma_phys_limit __ro_after_init; >>> #define CRASH_ADDR_LOW_MAX arm64_dma_phys_limit >>> #define CRASH_ADDR_HIGH_MAX MEMBLOCK_ALLOC_ACCESSIBLE >>> >>> +static int __init reserve_crashkernel_low(unsigned long long low_size) >>> +{ >>> + unsigned long long low_base; >>> + >>> + /* passed with crashkernel=0,low ? */ >>> + if (!low_size) >>> + return 0; >>> + >>> + low_base = memblock_phys_alloc_range(low_size, CRASH_ALIGN, 0, CRASH_ADDR_LOW_MAX); >>> + if (!low_base) { >>> + pr_err("cannot allocate crashkernel low memory (size:0x%llx).\n", low_size); >>> + return -ENOMEM; >>> + } >>> + >>> + pr_info("crashkernel low memory reserved: 0x%llx - 0x%llx (%lld MB)\n", >>> + low_base, low_base + low_size, low_size >> 20); >>> + >>> + crashk_low_res.start = low_base; >>> + crashk_low_res.end = low_base + low_size - 1; >>> + insert_resource(&iomem_resource, &crashk_low_res); >>> + >>> + return 0; >>> +} >>> + >>> /* >>> * reserve_crashkernel() - reserves memory for crash kernel >> >> My another concern is the crashkernel=,low handling. In this patch, the >> code related to low memory is obscure. Wondering if we should make them >> explicit with a little redundant but very clear code flows. Saying this >> because the code must be very clear to you and reviewers, it may be >> harder for later code reader or anyone interested to understand. >> >> 1) crashkernel=X,high >> 2) crashkernel=X,high crashkernel=Y,low >> 3) crashkernel=X,high crashkernel=0,low >> 4) crashkernel=X,high crashkernel='messy code',low >> 5) crashkernel=X //fall back to high memory, low memory is required then. >> >> It could be me thinking about it too much. I made changes to your patch >> with a tuning, not sure if it's OK to you. Otherwise, this patchset > > I think it's good. > >> works very well for all above test cases, it's ripe to be merged for >> wider testing. > > I will test it tomorrow. I've prepared a little more use cases than yours. After the following modifications, I have tested it and it works well. Passed all the test cases I prepared. > > 1) crashkernel=4G //high=4G, low=256M > 2) crashkernel=4G crashkernel=512M,high crashkernel=512M,low //high=4G, low=256M, high and low are ignored > 3) crashkernel=4G crashkernel=512M,high //high=4G, low=256M, high is ignored > 4) crashkernel=4G crashkernel=512M,low //high=4G, low=256M, low is ignored > 5) crashkernel=4G@0xe0000000 //high=0G, low=0M, cannot allocate, failed > 6) crashkernel=512M //high=0G, low=512M > 7) crashkernel=128M //high=0G, low=128M > 8) crashkernel=512M@0xde000000 //512M@3552M //high=0G, low=512M > 9) crashkernel=4G,high //high=4G, low=256M > a) crashkernel=4G,high crashkernel=512M,low //high=4G, low=512M > b) crashkernel=512M,high crashkernel=128M,low //high=512M, low=128M > c) crashkernel=512M,low //high=0G, low=0M, invalid > > >> >> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c >> index a5d43feac0d7..671862c56d7d 100644 >> --- a/arch/arm64/mm/init.c >> +++ b/arch/arm64/mm/init.c >> @@ -94,7 +94,8 @@ static int __init reserve_crashkernel_low(unsigned long long low_size) >> >> return 0; >> } >> - >> +/*Words explaining why it's 256M*/ >> +#define DEFAULT_CRASH_KERNEL_LOW_SIZE SZ_256M It's an empirical value. 94fb9334182284e8e7e4bcb9125c25dc33af19d4 x86/crash: Allocate enough low memory when crashkernel=high When the crash kernel is loaded above 4GiB in memory, the first kernel allocates only 72MiB of low-memory for the DMA requirements of the second kernel. On systems with many devices this is not enough and causes device driver initialization errors and failed crash dumps. Testing by SUSE and Redhat has shown that 256MiB is a good default value for now and the discussion has lead to this value as well. So set this default value to 256MiB to make sure there is enough memory available for DMA. >> /* >> * reserve_crashkernel() - reserves memory for crash kernel >> * >> @@ -105,10 +106,10 @@ static int __init reserve_crashkernel_low(unsigned long long low_size) >> static void __init reserve_crashkernel(void) >> { >> unsigned long long crash_base, crash_size; >> - unsigned long long crash_low_size = SZ_256M; >> + unsigned long long crash_low_size; >> unsigned long long crash_max = CRASH_ADDR_LOW_MAX; >> int ret; >> - bool fixed_base; >> + bool fixed_base, high; high = false; >> char *cmdline = boot_command_line; >> >> /* crashkernel=X[@offset] */ >> @@ -126,7 +127,10 @@ static void __init reserve_crashkernel(void) >> ret = parse_crashkernel_low(cmdline, 0, &low_size, &crash_base); >> if (!ret) >> crash_low_size = low_size; >> + else >> + crash_low_size = DEFAULT_CRASH_KERNEL_LOW_SIZE; >> >> + high = true; >> crash_max = CRASH_ADDR_HIGH_MAX; >> } >> >> @@ -134,7 +138,7 @@ static void __init reserve_crashkernel(void) >> crash_size = PAGE_ALIGN(crash_size); >> >> /* User specifies base address explicitly. */ >> - if (crash_base) >> + if (fixed_base) >> crash_max = crash_base + crash_size; >> >> retry: >> @@ -156,7 +160,10 @@ static void __init reserve_crashkernel(void) >> return; >> } >> >> - if (crash_base >= SZ_4G && reserve_crashkernel_low(crash_low_size)) { >> + if (crash_base >= SZ_4G && !high) >> + crash_low_size = DEFAULT_CRASH_KERNEL_LOW_SIZE; >> + >> + if (reserve_crashkernel_low(crash_low_size)) { >> memblock_phys_free(crash_base, crash_size); >> return; >> } - if (crash_base >= SZ_4G && reserve_crashkernel_low(crash_low_size)) { - memblock_phys_free(crash_base, crash_size); - return; + if (crash_base >= SZ_4G) { + if (!high) + crash_low_size = SZ_256M; + + if (reserve_crashkernel_low(crash_low_size)) { + memblock_phys_free(crash_base, crash_size); + return; + } } Looks like changing 'high' to 'low' would be more accurate. Whether crashkernel=Y,low is specified. > > It feels like {} may need to be added here so that it is in branch "if (crash_base >= SZ_4G)". > The case of "crashkernel=128M" will not fall back to high memory and does not need to reserve > low memory again. > >> >>> * >>> @@ -81,29 +105,62 @@ phys_addr_t arm64_dma_phys_limit __ro_after_init; >>> static void __init reserve_crashkernel(void) >>> { >>> unsigned long long crash_base, crash_size; >>> + unsigned long long crash_low_size = SZ_256M; >>> unsigned long long crash_max = CRASH_ADDR_LOW_MAX; >>> int ret; >>> + bool fixed_base; >>> + char *cmdline = boot_command_line; >>> >>> - ret = parse_crashkernel(boot_command_line, memblock_phys_mem_size(), >>> + /* crashkernel=X[@offset] */ >>> + ret = parse_crashkernel(cmdline, memblock_phys_mem_size(), >>> &crash_size, &crash_base); >>> - /* no crashkernel= or invalid value specified */ >>> - if (ret || !crash_size) >>> - return; >>> + if (ret || !crash_size) { >>> + unsigned long long low_size; >>> >>> + /* crashkernel=X,high */ >>> + ret = parse_crashkernel_high(cmdline, 0, &crash_size, &crash_base); >>> + if (ret || !crash_size) >>> + return; >>> + >>> + /* crashkernel=X,low */ >>> + ret = parse_crashkernel_low(cmdline, 0, &low_size, &crash_base); >>> + if (!ret) >>> + crash_low_size = low_size; >>> + >>> + crash_max = CRASH_ADDR_HIGH_MAX; >>> + } >>> + >>> + fixed_base = !!crash_base; >>> crash_size = PAGE_ALIGN(crash_size); >>> >>> /* User specifies base address explicitly. */ >>> if (crash_base) >>> crash_max = crash_base + crash_size; >>> >>> +retry: >>> crash_base = memblock_phys_alloc_range(crash_size, CRASH_ALIGN, >>> crash_base, crash_max); >>> if (!crash_base) { >>> + /* >>> + * Attempt to fully allocate low memory failed, fall back >>> + * to high memory, the minimum required low memory will be >>> + * reserved later. >>> + */ >>> + if (!fixed_base && (crash_max == CRASH_ADDR_LOW_MAX)) { >>> + crash_max = CRASH_ADDR_HIGH_MAX; >>> + goto retry; >>> + } >>> + >>> pr_warn("cannot allocate crashkernel (size:0x%llx)\n", >>> crash_size); >>> return; >>> } >>> >>> + if (crash_base >= SZ_4G && reserve_crashkernel_low(crash_low_size)) { >>> + memblock_phys_free(crash_base, crash_size); >>> + return; >>> + } >>> + >>> pr_info("crashkernel reserved: 0x%016llx - 0x%016llx (%lld MB)\n", >>> crash_base, crash_base + crash_size, crash_size >> 20); >>> >>> @@ -112,6 +169,9 @@ static void __init reserve_crashkernel(void) >>> * map. Inform kmemleak so that it won't try to access it. >>> */ >>> kmemleak_ignore_phys(crash_base); >>> + if (crashk_low_res.end) >>> + kmemleak_ignore_phys(crashk_low_res.start); >>> + >>> crashk_res.start = crash_base; >>> crashk_res.end = crash_base + crash_size - 1; >>> insert_resource(&iomem_resource, &crashk_res); >>> -- >>> 2.25.1 >>> >> >> . >> >
On 02/16/22 at 10:58am, Leizhen (ThunderTown) wrote: > > > On 2022/2/14 15:53, Leizhen (ThunderTown) wrote: > > > > > > On 2022/2/14 11:52, Baoquan He wrote: > >> On 01/24/22 at 04:47pm, Zhen Lei wrote: > >> ...... > >>> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c > >>> index 6c653a2c7cff052..a5d43feac0d7d96 100644 > >>> --- a/arch/arm64/mm/init.c > >>> +++ b/arch/arm64/mm/init.c > >>> @@ -71,6 +71,30 @@ phys_addr_t arm64_dma_phys_limit __ro_after_init; > >>> #define CRASH_ADDR_LOW_MAX arm64_dma_phys_limit > >>> #define CRASH_ADDR_HIGH_MAX MEMBLOCK_ALLOC_ACCESSIBLE > >>> > >>> +static int __init reserve_crashkernel_low(unsigned long long low_size) > >>> +{ > >>> + unsigned long long low_base; > >>> + > >>> + /* passed with crashkernel=0,low ? */ > >>> + if (!low_size) > >>> + return 0; > >>> + > >>> + low_base = memblock_phys_alloc_range(low_size, CRASH_ALIGN, 0, CRASH_ADDR_LOW_MAX); > >>> + if (!low_base) { > >>> + pr_err("cannot allocate crashkernel low memory (size:0x%llx).\n", low_size); > >>> + return -ENOMEM; > >>> + } > >>> + > >>> + pr_info("crashkernel low memory reserved: 0x%llx - 0x%llx (%lld MB)\n", > >>> + low_base, low_base + low_size, low_size >> 20); > >>> + > >>> + crashk_low_res.start = low_base; > >>> + crashk_low_res.end = low_base + low_size - 1; > >>> + insert_resource(&iomem_resource, &crashk_low_res); > >>> + > >>> + return 0; > >>> +} > >>> + > >>> /* > >>> * reserve_crashkernel() - reserves memory for crash kernel > >> > >> My another concern is the crashkernel=,low handling. In this patch, the > >> code related to low memory is obscure. Wondering if we should make them > >> explicit with a little redundant but very clear code flows. Saying this > >> because the code must be very clear to you and reviewers, it may be > >> harder for later code reader or anyone interested to understand. > >> > >> 1) crashkernel=X,high > >> 2) crashkernel=X,high crashkernel=Y,low > >> 3) crashkernel=X,high crashkernel=0,low > >> 4) crashkernel=X,high crashkernel='messy code',low > >> 5) crashkernel=X //fall back to high memory, low memory is required then. > >> > >> It could be me thinking about it too much. I made changes to your patch > >> with a tuning, not sure if it's OK to you. Otherwise, this patchset > > > > I think it's good. > > > >> works very well for all above test cases, it's ripe to be merged for > >> wider testing. > > > > I will test it tomorrow. I've prepared a little more use cases than yours. > > After the following modifications, I have tested it and it works well. Passed > all the test cases I prepared. That's great. You might need to add 'crashkernel=xM, crashkernel=0,low', 'crashkernel=xM, crashkernel='messy code',low' to your test cases. > > > > > 1) crashkernel=4G //high=4G, low=256M > > 2) crashkernel=4G crashkernel=512M,high crashkernel=512M,low //high=4G, low=256M, high and low are ignored > > 3) crashkernel=4G crashkernel=512M,high //high=4G, low=256M, high is ignored > > 4) crashkernel=4G crashkernel=512M,low //high=4G, low=256M, low is ignored > > 5) crashkernel=4G@0xe0000000 //high=0G, low=0M, cannot allocate, failed > > 6) crashkernel=512M //high=0G, low=512M > > 7) crashkernel=128M //high=0G, low=128M > > 8) crashkernel=512M@0xde000000 //512M@3552M //high=0G, low=512M > > 9) crashkernel=4G,high //high=4G, low=256M > > a) crashkernel=4G,high crashkernel=512M,low //high=4G, low=512M > > b) crashkernel=512M,high crashkernel=128M,low //high=512M, low=128M > > c) crashkernel=512M,low //high=0G, low=0M, invalid > > > > > >> > >> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c > >> index a5d43feac0d7..671862c56d7d 100644 > >> --- a/arch/arm64/mm/init.c > >> +++ b/arch/arm64/mm/init.c > >> @@ -94,7 +94,8 @@ static int __init reserve_crashkernel_low(unsigned long long low_size) > >> > >> return 0; > >> } > >> - > >> +/*Words explaining why it's 256M*/ > >> +#define DEFAULT_CRASH_KERNEL_LOW_SIZE SZ_256M > > It's an empirical value. > > 94fb9334182284e8e7e4bcb9125c25dc33af19d4 x86/crash: Allocate enough low memory when crashkernel=high > > When the crash kernel is loaded above 4GiB in memory, the > first kernel allocates only 72MiB of low-memory for the DMA > requirements of the second kernel. On systems with many > devices this is not enough and causes device driver > initialization errors and failed crash dumps. Testing by > SUSE and Redhat has shown that 256MiB is a good default > value for now and the discussion has lead to this value as > well. So set this default value to 256MiB to make sure there > is enough memory available for DMA. Then, some words like below can be added. I am not confident it's good enought, hope someone else can help to polish it. /* * This is an empirical value in x86_64 and taken here directly. Please * refer to code comment in reserve_crashkernel_low() of x86_64 for more * details. */ #define DEFAULT_CRASH_KERNEL_LOW_SIZE SZ_256M > > > >> /* > >> * reserve_crashkernel() - reserves memory for crash kernel > >> * > >> @@ -105,10 +106,10 @@ static int __init reserve_crashkernel_low(unsigned long long low_size) > >> static void __init reserve_crashkernel(void) > >> { > >> unsigned long long crash_base, crash_size; > >> - unsigned long long crash_low_size = SZ_256M; > >> + unsigned long long crash_low_size; > >> unsigned long long crash_max = CRASH_ADDR_LOW_MAX; > >> int ret; > >> - bool fixed_base; > >> + bool fixed_base, high; > > high = false; > > >> char *cmdline = boot_command_line; > >> > >> /* crashkernel=X[@offset] */ > >> @@ -126,7 +127,10 @@ static void __init reserve_crashkernel(void) > >> ret = parse_crashkernel_low(cmdline, 0, &low_size, &crash_base); > >> if (!ret) > >> crash_low_size = low_size; > >> + else > >> + crash_low_size = DEFAULT_CRASH_KERNEL_LOW_SIZE; > >> > >> + high = true; > >> crash_max = CRASH_ADDR_HIGH_MAX; > >> } > >> > >> @@ -134,7 +138,7 @@ static void __init reserve_crashkernel(void) > >> crash_size = PAGE_ALIGN(crash_size); > >> > >> /* User specifies base address explicitly. */ > >> - if (crash_base) > >> + if (fixed_base) > >> crash_max = crash_base + crash_size; > >> > >> retry: > >> @@ -156,7 +160,10 @@ static void __init reserve_crashkernel(void) > >> return; > >> } > >> > >> - if (crash_base >= SZ_4G && reserve_crashkernel_low(crash_low_size)) { > >> + if (crash_base >= SZ_4G && !high) > >> + crash_low_size = DEFAULT_CRASH_KERNEL_LOW_SIZE; > >> + > >> + if (reserve_crashkernel_low(crash_low_size)) { > >> memblock_phys_free(crash_base, crash_size); > >> return; > >> } > > - if (crash_base >= SZ_4G && reserve_crashkernel_low(crash_low_size)) { > - memblock_phys_free(crash_base, crash_size); > - return; > + if (crash_base >= SZ_4G) { > + if (!high) > + crash_low_size = SZ_256M; > + > + if (reserve_crashkernel_low(crash_low_size)) { > + memblock_phys_free(crash_base, crash_size); > + return; > + } > } > > Looks like changing 'high' to 'low' would be more accurate. Whether crashkernel=Y,low is specified. What I menat is like below, we even can add code comment to make it more clearer. static void __init reserve_crashkernel(void) { /* crashkernel=X[@offset] */ ret = parse_crashkernel(cmdline, memblock_phys_mem_size(), &crash_size, &crash_base); if (ret || !crash_size) { unsigned long long low_size; /* crashkernel=X,high */ ret = parse_crashkernel_high(cmdline, 0, &crash_size, &crash_base); if (ret || !crash_size) return; /* crashkernel=X,low */ ret = parse_crashkernel_low(cmdline, 0, &low_size, &crash_base); //case #1, crashkernel=yM,low is specified explicitly in cmdline if (!ret) crash_low_size = low_size; else //case #2, crashkernel=yM,low is not specified explicitly crash_low_size = DEFAULT_CRASH_KERNEL_LOW_SIZE; //high means crashkernel,high is specified explicitly high = true; crash_max = CRASH_ADDR_HIGH_MAX; } fixed_base = !!crash_base; crash_size = PAGE_ALIGN(crash_size); /* User specifies base address explicitly. */ if (crash_base) crash_max = crash_base + crash_size; retry: crash_base = memblock_phys_alloc_range(crash_size, CRASH_ALIGN, crash_base, crash_max); if (!crash_base) { /* * Attempt to fully allocate low memory failed, fall back * to high memory, the minimum required low memory will be * reserved later. */ if (!fixed_base && (crash_max == CRASH_ADDR_LOW_MAX)) { crash_max = CRASH_ADDR_HIGH_MAX; goto retry; } pr_warn("cannot allocate crashkernel (size:0x%llx)\n", crash_size); return; } //case #3: get crashkernel from high memory through fallback, let's set crashkernel,low too. if (crash_base >= SZ_4G && !high) crash_low_size = DEFAULT_CRASH_KERNEL_LOW_SIZE; if (reserve_crashkernel_low(crash_low_size)) { memblock_phys_free(crash_base, crash_size); return; } pr_info("crashkernel reserved: 0x%016llx - 0x%016llx (%lld MB)\n", crash_base, crash_base + crash_size, crash_size >> 20); /* * The crashkernel memory will be removed from the kernel linear * map. Inform kmemleak so that it won't try to access it. */ kmemleak_ignore_phys(crash_base); if (crashk_low_res.end) kmemleak_ignore_phys(crashk_low_res.start); crashk_res.start = crash_base; crashk_res.end = crash_base + crash_size - 1; insert_resource(&iomem_resource, &crashk_res); } > > > > > > It feels like {} may need to be added here so that it is in branch "if (crash_base >= SZ_4G)". > > The case of "crashkernel=128M" will not fall back to high memory and does not need to reserve > > low memory again. > > > >> > >>> * > >>> @@ -81,29 +105,62 @@ phys_addr_t arm64_dma_phys_limit __ro_after_init; > >>> static void __init reserve_crashkernel(void) > >>> { > >>> unsigned long long crash_base, crash_size; > >>> + unsigned long long crash_low_size = SZ_256M; > >>> unsigned long long crash_max = CRASH_ADDR_LOW_MAX; > >>> int ret; > >>> + bool fixed_base; > >>> + char *cmdline = boot_command_line; > >>> > >>> - ret = parse_crashkernel(boot_command_line, memblock_phys_mem_size(), > >>> + /* crashkernel=X[@offset] */ > >>> + ret = parse_crashkernel(cmdline, memblock_phys_mem_size(), > >>> &crash_size, &crash_base); > >>> - /* no crashkernel= or invalid value specified */ > >>> - if (ret || !crash_size) > >>> - return; > >>> + if (ret || !crash_size) { > >>> + unsigned long long low_size; > >>> > >>> + /* crashkernel=X,high */ > >>> + ret = parse_crashkernel_high(cmdline, 0, &crash_size, &crash_base); > >>> + if (ret || !crash_size) > >>> + return; > >>> + > >>> + /* crashkernel=X,low */ > >>> + ret = parse_crashkernel_low(cmdline, 0, &low_size, &crash_base); > >>> + if (!ret) > >>> + crash_low_size = low_size; > >>> + > >>> + crash_max = CRASH_ADDR_HIGH_MAX; > >>> + } > >>> + > >>> + fixed_base = !!crash_base; > >>> crash_size = PAGE_ALIGN(crash_size); > >>> > >>> /* User specifies base address explicitly. */ > >>> if (crash_base) > >>> crash_max = crash_base + crash_size; > >>> > >>> +retry: > >>> crash_base = memblock_phys_alloc_range(crash_size, CRASH_ALIGN, > >>> crash_base, crash_max); > >>> if (!crash_base) { > >>> + /* > >>> + * Attempt to fully allocate low memory failed, fall back > >>> + * to high memory, the minimum required low memory will be > >>> + * reserved later. > >>> + */ > >>> + if (!fixed_base && (crash_max == CRASH_ADDR_LOW_MAX)) { > >>> + crash_max = CRASH_ADDR_HIGH_MAX; > >>> + goto retry; > >>> + } > >>> + > >>> pr_warn("cannot allocate crashkernel (size:0x%llx)\n", > >>> crash_size); > >>> return; > >>> } > >>> > >>> + if (crash_base >= SZ_4G && reserve_crashkernel_low(crash_low_size)) { > >>> + memblock_phys_free(crash_base, crash_size); > >>> + return; > >>> + } > >>> + > >>> pr_info("crashkernel reserved: 0x%016llx - 0x%016llx (%lld MB)\n", > >>> crash_base, crash_base + crash_size, crash_size >> 20); > >>> > >>> @@ -112,6 +169,9 @@ static void __init reserve_crashkernel(void) > >>> * map. Inform kmemleak so that it won't try to access it. > >>> */ > >>> kmemleak_ignore_phys(crash_base); > >>> + if (crashk_low_res.end) > >>> + kmemleak_ignore_phys(crashk_low_res.start); > >>> + > >>> crashk_res.start = crash_base; > >>> crashk_res.end = crash_base + crash_size - 1; > >>> insert_resource(&iomem_resource, &crashk_res); > >>> -- > >>> 2.25.1 > >>> > >> > >> . > >> > > > > -- > Regards, > Zhen Lei >
There are following issues in arm64 kdump: 1. We use crashkernel=X to reserve crashkernel below 4G, which will fail when there is no enough low memory. 2. If reserving crashkernel above 4G, in this case, crash dump kernel will boot failure because there is no low memory available for allocation. To solve these issues, change the behavior of crashkernel=X. crashkernel=X tries low allocation in DMA zone and fall back to high allocation if it fails. We can also use "crashkernel=X,high" to select a high region above DMA zone, which also tries to allocate at least 256M low memory in DMA zone automatically and "crashkernel=Y,low" can be used to allocate specified size low memory. When reserving crashkernel in high memory, some low memory is reserved for crash dump kernel devices. So there may be two regions reserved for crash dump kernel. In order to distinct from the high region and make no effect to the use of existing kexec-tools, rename the low region as "Crash kernel (low)", and pass the low region by reusing DT property "linux,usable-memory-range". We made the low memory region as the last range of "linux,usable-memory-range" to keep compatibility with existing user-space and older kdump kernels. Besides, we need to modify kexec-tools: arm64: support more than one crash kernel regions(see [1]) Another update is document about DT property 'linux,usable-memory-range': schemas: update 'linux,usable-memory-range' node schema(see [2]) Changes since [v19]: 1. Temporarily stop making reserve_crashkernel[_low]() generic. There are a lot of details need to be considered, which can take a long time. Because "make generic" does not add new functions and does not improve performance, maybe I should say it's just a cleanup. So by stripping it out and leaving it for other patches later, we can aggregate the changes to the main functions. 2. Use insert_resource() to replace request_resource(), this not only simplifies the code, but also reduces the differences between arm64 and x86 implementations. 3. As commit 157752d84f5d ("kexec: use Crash kernel for Crash kernel low") do for x86, we can also extend kexec-tools for arm64, and it's currently applied. See: https://www.spinics.net/lists/kexec/msg28284.html Thank you very much, Borislav Petkov, for so many valuable comments. Changes since [v17]: v17 --> v19 1. Patch 0001-0004 Introduce generic parse_crashkernel_high_low() to bring the parsing of "crashkernel=X,high" and the parsing of "crashkernel=X,low" together, then use it instead of the call to parse_crashkernel_{high|low}(). Two confusing parameters of parse_crashkernel_{high|low}() are deleted. I previously sent these four patches separately: [1] https://lkml.org/lkml/2021/12/25/40 2. Patch 0005-0009 Introduce generic reserve_crashkernel_mem[_low](), the implementation of these two functions is based on function reserve_crashkernel[_low]() in arch/x86/kernel/setup.c. There is no functional change for x86. 1) The check position of xen_pv_domain() does not change. 2) Still 1M alignment for crash kernel fixed region, when 'base' is specified. To avoid compilation problems on other architectures: patch 0004 moves the definition of global variable crashk[_low]_res from kexec_core.c to crash_core.c, and provide default definitions for all macros involved, a particular platform can redefine these macros to override the default values. 3. 0010, only one line of comment was changed. 4. 0011 1) crashk_low_res may also a valid reserved memory, should be checked in crash_is_nosave(), see arch/arm64/kernel/machine_kexec. 2) Drop memblock_mark_nomap() for crashk_low_res, because of: 2687275a5843 arm64: Force NO_BLOCK_MAPPINGS if crashkernel reservation is required 3) Also call kmemleak_ignore_phys() for crashk_low_res, because of: 85f58eb18898 arm64: kdump: Skip kmemleak scan reserved memory for kdump 5. 0012, slightly rebased, because the following patch is applied in advance. https://git.kernel.org/pub/scm/linux/kernel/git/robh/linux.git/commit/?h=dt/linus&id=8347b41748c3019157312fbe7f8a6792ae396eb7 6. 0013, no change. Others: 1. Discard add ARCH_WANT_RESERVE_CRASH_KERNEL 2. When allocating crash low memory, the start address still starts from 0. low_base = memblock_phys_alloc_range(low_size, CRASH_ALIGN, 0, CRASH_ADDR_LOW_MAX); 3. Discard change (1ULL << 32) to CRASH_ADDR_LOW_MAX. 4. Ensure the check position of xen_pv_domain() have no change. 5. Except patch 0010 and 0012, all "Tested-by", "Reviewed-by", "Acked-by" are removed. 6. Update description. Changes since [v16] - Because no functional changes in this version, so add "Tested-by: Dave Kleikamp <dave.kleikamp@oracle.com>" for patch 1-9 - Add "Reviewed-by: Rob Herring <robh@kernel.org>" for patch 8 - Update patch 9 based on the review comments of Rob Herring - As Catalin Marinas's suggestion, merge the implementation of ARCH_WANT_RESERVE_CRASH_KERNEL into patch 5. Ensure that the contents of X86 and ARM64 do not overlap, and reduce unnecessary temporary differences. Changes since [v15] - Aggregate the processing of "linux,usable-memory-range" into one function. Only patch 9-10 have been updated. Changes since [v14] - Recovering the requirement that the CrashKernel memory regions on X86 only requires 1 MiB alignment. - Combine patches 5 and 6 in v14 into one. The compilation warning fixed by patch 6 was introduced by patch 5 in v14. - As with crashk_res, crashk_low_res is also processed by crash_exclude_mem_range() in patch 7. - Due to commit b261dba2fdb2 ("arm64: kdump: Remove custom linux,usable-memory-range handling") has removed the architecture-specific code, extend the property "linux,usable-memory-range" in the platform-agnostic FDT core code. See patch 9. - Discard the x86 description update in the document, because the description has been updated by commit b1f4c363666c ("Documentation: kdump: update kdump guide"). - Change "arm64" to "ARM64" in Doc. Changes since [v13] - Rebased on top of 5.11-rc5. - Introduce config CONFIG_ARCH_WANT_RESERVE_CRASH_KERNEL. Since reserve_crashkernel[_low]() implementations are quite similar on other architectures, so have CONFIG_ARCH_WANT_RESERVE_CRASH_KERNEL in arch/Kconfig and select this by X86 and ARM64. - Some minor cleanup. Changes since [v12] - Rebased on top of 5.10-rc1. - Keep CRASH_ALIGN as 16M suggested by Dave. - Drop patch "kdump: add threshold for the required memory". - Add Tested-by from John. Changes since [v11] - Rebased on top of 5.9-rc4. - Make the function reserve_crashkernel() of x86 generic. Suggested by Catalin, make the function reserve_crashkernel() of x86 generic and arm64 use the generic version to reimplement crashkernel=X. Changes since [v10] - Reimplement crashkernel=X suggested by Catalin, Many thanks to Catalin. Changes since [v9] - Patch 1 add Acked-by from Dave. - Update patch 5 according to Dave's comments. - Update chosen schema. Changes since [v8] - Reuse DT property "linux,usable-memory-range". Suggested by Rob, reuse DT property "linux,usable-memory-range" to pass the low memory region. - Fix kdump broken with ZONE_DMA reintroduced. - Update chosen schema. Changes since [v7] - Move x86 CRASH_ALIGN to 2M Suggested by Dave and do some test, move x86 CRASH_ALIGN to 2M. - Update Documentation/devicetree/bindings/chosen.txt. Add corresponding documentation to Documentation/devicetree/bindings/chosen.txt suggested by Arnd. - Add Tested-by from Jhon and pk. Changes since [v6] - Fix build errors reported by kbuild test robot. Changes since [v5] - Move reserve_crashkernel_low() into kernel/crash_core.c. - Delete crashkernel=X,high. - Modify crashkernel=X,low. If crashkernel=X,low is specified simultaneously, reserve spcified size low memory for crash kdump kernel devices firstly and then reserve memory above 4G. In addition, rename crashk_low_res as "Crash kernel (low)" for arm64, and then pass to crash dump kernel by DT property "linux,low-memory-range". - Update Documentation/admin-guide/kdump/kdump.rst. Changes since [v4] - Reimplement memblock_cap_memory_ranges for multiple ranges by Mike. Changes since [v3] - Add memblock_cap_memory_ranges back for multiple ranges. - Fix some compiling warnings. Changes since [v2] - Split patch "arm64: kdump: support reserving crashkernel above 4G" as two. Put "move reserve_crashkernel_low() into kexec_core.c" in a separate patch. Changes since [v1]: - Move common reserve_crashkernel_low() code into kernel/kexec_core.c. - Remove memblock_cap_memory_ranges() i added in v1 and implement that in fdt_enforce_memory_region(). There are at most two crash kernel regions, for two crash kernel regions case, we cap the memory range [min(regs[*].start), max(regs[*].end)] and then remove the memory range in the middle. [1]: https://www.spinics.net/lists/kexec/msg28226.html [2]: https://github.com/robherring/dt-schema/pull/19 [v1]: https://lkml.org/lkml/2019/4/2/1174 [v2]: https://lkml.org/lkml/2019/4/9/86 [v3]: https://lkml.org/lkml/2019/4/9/306 [v4]: https://lkml.org/lkml/2019/4/15/273 [v5]: https://lkml.org/lkml/2019/5/6/1360 [v6]: https://lkml.org/lkml/2019/8/30/142 [v7]: https://lkml.org/lkml/2019/12/23/411 [v8]: https://lkml.org/lkml/2020/5/21/213 [v9]: https://lkml.org/lkml/2020/6/28/73 [v10]: https://lkml.org/lkml/2020/7/2/1443 [v11]: https://lkml.org/lkml/2020/8/1/150 [v12]: https://lkml.org/lkml/2020/9/7/1037 [v13]: https://lkml.org/lkml/2020/10/31/34 [v14]: https://lkml.org/lkml/2021/1/30/53 [v15]: https://lkml.org/lkml/2021/10/19/1405 [v16]: https://lkml.org/lkml/2021/11/23/435 [v17]: https://lkml.org/lkml/2021/12/10/38 [v18]: https://lkml.org/lkml/2021/12/22/424 [v19]: https://lkml.org/lkml/2021/12/28/203 Chen Zhou (4): arm64: kdump: introduce some macros for crash kernel reservation arm64: kdump: reimplement crashkernel=X of: fdt: Add memory for devices by DT property "linux,usable-memory-range" kdump: update Documentation about crashkernel Zhen Lei (1): arm64: Use insert_resource() to simplify code Documentation/admin-guide/kdump/kdump.rst | 11 ++- .../admin-guide/kernel-parameters.txt | 11 ++- arch/arm64/kernel/machine_kexec.c | 9 ++- arch/arm64/kernel/machine_kexec_file.c | 12 ++- arch/arm64/kernel/setup.c | 17 +--- arch/arm64/mm/init.c | 80 +++++++++++++++++-- drivers/of/fdt.c | 33 +++++--- 7 files changed, 134 insertions(+), 39 deletions(-)