| Message ID | 20211228132612.1860-1-thunder.leizhen@huawei.com |
|---|---|
| Headers | show |
| Series | support reserving crashkernel above 4G on arm64 kdump | expand |
On 2021/12/31 17:22, Leizhen (ThunderTown) wrote: > > > On 2021/12/30 19:08, Leizhen (ThunderTown) wrote: >> >> >> On 2021/12/30 18:40, Borislav Petkov wrote: >>> On Thu, Dec 30, 2021 at 06:14:59PM +0800, Leizhen (ThunderTown) wrote: >>>> >>>> Hi, Dave, Baoquan, Borislav: >>>> What do you think about the introduction of parse_crashkernel_high_low()? If everyone >>>> doesn't object, I'll bring it to the next version. But I'll make some adjustments to the >>>> patches, see below. If there's any objection, I still strongly recommend removing the >>>> parameters "system_ram" and "crash_base" of parse_crashkernel_{high,low}(). >>>> >>>> How about splitting __parse_crashkernel() into two parts? One for parsing >>>> "crashkernel=X[@offset]", another one for parsing "crashkernel=X,{high,low}" and other >>>> suffixes in the future. So the parameter requirements are clear at the lowest level. >>> >>> First of all, please do not top post! >>> >>> Now, I already explained to you what I'd like to see: >>> >>> https://lore.kernel.org/r/Ycs3kpZD/vpoo1AX@zn.tnic >>> >>> yet you still don't get it. >>> >>> So let me make myself clear: in its current form, this is not really an >>> improvement so for all x86 changes: >>> >>> NAKed-by: Borislav Petkov <bp@suse.de> > > Hi Borislav: > I'm sorry to bother you again. Do you mind if I make the following changes? > I can't stand so many comments appearing twice. Even if the size needs to be > changed in the future, mode "low_size = CRASH_LOW_SIZE_MIN + <increment>" can > be used for adaptation without affecting other architectures. I rethink it, the default value of default_nslabs is IO_TLB_DEFAULT_SIZE=64M. The value of default_nslabs can only be changed by swiotlb_adjust_size() and bootup command line option "swiotlb=". Currently, swiotlb_adjust_size() is invoked only on x86, so I can just ignore it on arm64. Then, 64M is much smaller than 256M, the first kernel works fine with the default 64M on arm64, and I don't think the second kernel needs to grow to 256M. Therefore, I think swiotlb_adjust_size() is probably a pseudo requirement for arm64. So I will directly use 256M on arm64. If anyone gets into trouble, he/she can add it back. Besides, there is also "crashkernel=Y,low" can be used. > > > diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c > index e04f5e6eb33f453..da485ee51a9929e 100644 > --- a/arch/x86/kernel/setup.c > +++ b/arch/x86/kernel/setup.c > @@ -428,16 +428,7 @@ static int __init reserve_crashkernel_low(void) > /* crashkernel=Y,low */ > ret = parse_crashkernel_low(boot_command_line, low_mem_limit, &low_size, &base); > if (ret) { > - /* > - * two parts from kernel/dma/swiotlb.c: > - * -swiotlb size: user-specified with swiotlb= or default. > - * > - * -swiotlb overflow buffer: now hardcoded to 32k. We round it > - * to 8M for other buffers that may need to stay low too. Also > - * make sure we allocate enough extra low memory so that we > - * don't run out of DMA buffers for 32-bit devices. > - */ > - low_size = max(swiotlb_size_or_default() + (8UL << 20), 256UL << 20); > + low_size = CRASH_LOW_SIZE_MIN; > } else { > /* passed with crashkernel=0,low ? */ > if (!low_size) > diff --git a/include/linux/crash_core.h b/include/linux/crash_core.h > index de62a722431e7db..c85b15814312b7e 100644 > --- a/include/linux/crash_core.h > +++ b/include/linux/crash_core.h > @@ -69,6 +69,17 @@ phys_addr_t paddr_vmcoreinfo_note(void); > #define VMCOREINFO_CONFIG(name) \ > vmcoreinfo_append_str("CONFIG_%s=y\n", #name) > > +/* > + * two parts from kernel/dma/swiotlb.c: > + * -swiotlb size: user-specified with swiotlb= or default. > + * > + * -swiotlb overflow buffer: now hardcoded to 32k. We round it > + * to 8M for other buffers that may need to stay low too. Also > + * make sure we allocate enough extra low memory so that we > + * don't run out of DMA buffers for 32-bit devices. > + */ > +#define CRASH_LOW_SIZE_MIN max(swiotlb_size_or_default() + (8UL << 20), 256UL << 20) > + > extern unsigned char *vmcoreinfo_data; > extern size_t vmcoreinfo_size; > extern u32 *vmcoreinfo_note; > > >>> >> >> OK, thanks for your immediate reply, so I can take less detours. >> >
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 [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]: http://lists.infradead.org/pipermail/kexec/2020-June/020737.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 Chen Zhou (6): kexec: move crashk[_low]_res to crash_core module x86/setup: Move CRASH[_BASE]_ALIGN and CRASH_ADDR_{LOW|HIGH}_MAX to asm/kexec.h 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 (7): kdump: add helper parse_crashkernel_high_low() x86/setup: Use parse_crashkernel_high_low() to simplify code kdump: make parse_crashkernel_{high|low}() static kdump: reduce unnecessary parameters of parse_crashkernel_{high|low}() x86/setup: Add and use CRASH_BASE_ALIGN kdump: Add helper reserve_crashkernel_mem[_low]() x86/setup: Use generic reserve_crashkernel_mem[_low]() Documentation/admin-guide/kdump/kdump.rst | 11 +- .../admin-guide/kernel-parameters.txt | 11 +- arch/arm64/include/asm/kexec.h | 6 + arch/arm64/kernel/machine_kexec.c | 5 +- arch/arm64/kernel/machine_kexec_file.c | 12 +- arch/arm64/kernel/setup.c | 13 +- arch/arm64/mm/init.c | 41 ++-- arch/x86/include/asm/kexec.h | 27 +++ arch/x86/kernel/setup.c | 128 +--------- drivers/of/fdt.c | 33 ++- include/linux/crash_core.h | 17 +- include/linux/kexec.h | 4 - kernel/crash_core.c | 224 +++++++++++++++++- kernel/kexec_core.c | 17 -- 14 files changed, 350 insertions(+), 199 deletions(-)