| Message ID | 20210108121524.656872-1-qperret@google.com |
|---|---|
| Headers | show |
| Series | KVM/arm64: A stage 2 for the host | expand |
Hi Quentin, On 2021-01-08 13:14, Quentin Perret wrote: > Hi all, > > This is the v2 of the series previously posted here: > > https://lore.kernel.org/kvmarm/20201117181607.1761516-1-qperret@google.com/ > > This basically allows us to wrap the host with a stage 2 when running in > nVHE, hence paving the way for protecting guest memory from the host in > the future (among other use-cases). For more details about the > motivation and the design angle taken here, I would recommend to have a > look at the cover letter of v1, and/or to watch these presentations at > LPC [1] and KVM forum 2020 [2]. We tested the pKVM changes pulled from here: > https://android-kvm.googlesource.com/linux qperret/host-stage2-v2 We were using a target with Arm architecture with FEAT_S2FWB, and found that there is a bug in the patch. It turned out that the Kernel checks for the extension, and sets up the stage 2 translation so that it forces the host memory type to write-through. However it seems that the code doesn't turn on the feature in the HCR_EL2 register. We were able to fix the issue by applying the following patch: diff --git a/arch/arm64/kvm/hyp/nvhe/mem_protect.c b/arch/arm64/kvm/hyp/nvhe/mem_protect.c index 0cd3eb178f3b..e8521a072ea6 100644 --- a/arch/arm64/kvm/hyp/nvhe/mem_protect.c +++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c @@ -105,6 +105,8 @@ int kvm_host_prepare_stage2(void *mem_pgt_pool, void *dev_pgt_pool) params->vttbr = kvm_get_vttbr(mmu); params->vtcr = host_kvm.arch.vtcr; params->hcr_el2 |= HCR_VM; + if (cpus_have_const_cap(ARM64_HAS_STAGE2_FWB)) + params->hcr_el2 |= HCR_FWB; __flush_dcache_area(params, sizeof(*params)); } Best regards, Mate Toth-Pal
Hi Mate, On Wednesday 17 Feb 2021 at 17:27:07 (+0100), Mate Toth-Pal wrote: > We tested the pKVM changes pulled from here: > > > > https://android-kvm.googlesource.com/linux qperret/host-stage2-v2 > > > We were using a target with Arm architecture with FEAT_S2FWB, and found that > there is a bug in the patch. > > > It turned out that the Kernel checks for the extension, and sets up the > stage 2 translation so that it forces the host memory type to write-through. > However it seems that the code doesn't turn on the feature in the HCR_EL2 > register. > > > We were able to fix the issue by applying the following patch: > > > diff --git a/arch/arm64/kvm/hyp/nvhe/mem_protect.c > b/arch/arm64/kvm/hyp/nvhe/mem_protect.c > index 0cd3eb178f3b..e8521a072ea6 100644 > --- a/arch/arm64/kvm/hyp/nvhe/mem_protect.c > +++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c > @@ -105,6 +105,8 @@ int kvm_host_prepare_stage2(void *mem_pgt_pool, void > *dev_pgt_pool) > params->vttbr = kvm_get_vttbr(mmu); > params->vtcr = host_kvm.arch.vtcr; > params->hcr_el2 |= HCR_VM; > + if (cpus_have_const_cap(ARM64_HAS_STAGE2_FWB)) > + params->hcr_el2 |= HCR_FWB; > __flush_dcache_area(params, sizeof(*params)); > } Aha, indeed, this looks right. I'll double check HCR_EL2 to see if I'm missing any other, and I'll add this to v3. Thanks for testing, and the for the report. Quentin
On Fri, Jan 08, 2021, Quentin Perret wrote:
> [2] https://kvmforum2020.sched.com/event/eE24/virtualization-for-the-masses-exposing-kvm-on-android-will-deacon-google
I couldn't find any slides on the official KVM forum site linked above. I was
able to track down a mirror[1] and the recorded presentation[2].
[1] https://mirrors.edge.kernel.org/pub/linux/kernel/people/will/slides/kvmforum-2020-edited.pdf
[2] https://youtu.be/wY-u6n75iXc
On Friday 19 Feb 2021 at 09:54:38 (-0800), Sean Christopherson wrote: > On Fri, Jan 08, 2021, Quentin Perret wrote: > > [2] https://kvmforum2020.sched.com/event/eE24/virtualization-for-the-masses-exposing-kvm-on-android-will-deacon-google > > I couldn't find any slides on the official KVM forum site linked above. I was > able to track down a mirror[1] and the recorded presentation[2]. > > [1] https://mirrors.edge.kernel.org/pub/linux/kernel/people/will/slides/kvmforum-2020-edited.pdf > [2] https://youtu.be/wY-u6n75iXc Much nicer, I'll make sure to link those in the next cover letter. Thanks Sean! Quentin
Hi all, This is the v2 of the series previously posted here: https://lore.kernel.org/kvmarm/20201117181607.1761516-1-qperret@google.com/ This basically allows us to wrap the host with a stage 2 when running in nVHE, hence paving the way for protecting guest memory from the host in the future (among other use-cases). For more details about the motivation and the design angle taken here, I would recommend to have a look at the cover letter of v1, and/or to watch these presentations at LPC [1] and KVM forum 2020 [2]. In short, the changes since v1 include: - Renamed most pkvm-specific pgtable functions as pkvm_* to avoid confusion with the host's (Fuad) - Added an IC flush when switching pgtables (Fuad, Mark) - Cleaned-up the PI aliasing in image-vars.h (David) - Added a TLB flush when enabling the host stage 2 to avoid stale TLBs from bootloader - Fixed the early memory reservation by using NR_CPUS instead of num_possible_cpus() (which is always 1 that early) - Added missing preempt_{dis,en}able() guards in kvm_hyp_enable_protection() - Rebased on latest kvmarm/next And if you'd like a branch that has all the goodies, there it is: https://android-kvm.googlesource.com/linux qperret/host-stage2-v2 Thanks! Quentin [1] https://youtu.be/54q6RzS9BpQ?t=10859 [2] https://kvmforum2020.sched.com/event/eE24/virtualization-for-the-masses-exposing-kvm-on-android-will-deacon-google Quentin Perret (23): KVM: arm64: Initialize kvm_nvhe_init_params early KVM: arm64: Avoid free_page() in page-table allocator KVM: arm64: Factor memory allocation out of pgtable.c KVM: arm64: Introduce a BSS section for use at Hyp KVM: arm64: Make kvm_call_hyp() a function call at Hyp KVM: arm64: Allow using kvm_nvhe_sym() in hyp code KVM: arm64: Introduce an early Hyp page allocator KVM: arm64: Stub CONFIG_DEBUG_LIST at Hyp KVM: arm64: Introduce a Hyp buddy page allocator KVM: arm64: Enable access to sanitized CPU features at EL2 KVM: arm64: Factor out vector address calculation of/fdt: Introduce early_init_dt_add_memory_hyp() KVM: arm64: Prepare Hyp memory protection KVM: arm64: Elevate Hyp mappings creation at EL2 KVM: arm64: Use kvm_arch for stage 2 pgtable KVM: arm64: Use kvm_arch in kvm_s2_mmu KVM: arm64: Set host stage 2 using kvm_nvhe_init_params KVM: arm64: Refactor kvm_arm_setup_stage2() KVM: arm64: Refactor __load_guest_stage2() KVM: arm64: Refactor __populate_fault_info() KVM: arm64: Make memcache anonymous in pgtable allocator KVM: arm64: Reserve memory for host stage 2 KVM: arm64: Wrap the host with a stage 2 Will Deacon (3): arm64: lib: Annotate {clear,copy}_page() as position-independent KVM: arm64: Link position-independent string routines into .hyp.text arm64: kvm: Add standalone ticket spinlock implementation for use at hyp arch/arm64/include/asm/cpufeature.h | 1 + arch/arm64/include/asm/hyp_image.h | 7 + arch/arm64/include/asm/kvm_asm.h | 7 + arch/arm64/include/asm/kvm_cpufeature.h | 19 ++ arch/arm64/include/asm/kvm_host.h | 16 +- arch/arm64/include/asm/kvm_hyp.h | 8 + arch/arm64/include/asm/kvm_mmu.h | 69 +++++- arch/arm64/include/asm/kvm_pgtable.h | 41 +++- arch/arm64/include/asm/sections.h | 1 + arch/arm64/kernel/asm-offsets.c | 3 + arch/arm64/kernel/cpufeature.c | 12 + arch/arm64/kernel/image-vars.h | 33 +++ arch/arm64/kernel/vmlinux.lds.S | 7 + arch/arm64/kvm/arm.c | 144 ++++++++++-- arch/arm64/kvm/hyp/Makefile | 2 +- arch/arm64/kvm/hyp/include/hyp/switch.h | 36 +-- arch/arm64/kvm/hyp/include/nvhe/early_alloc.h | 14 ++ arch/arm64/kvm/hyp/include/nvhe/gfp.h | 32 +++ arch/arm64/kvm/hyp/include/nvhe/mem_protect.h | 33 +++ arch/arm64/kvm/hyp/include/nvhe/memory.h | 55 +++++ arch/arm64/kvm/hyp/include/nvhe/mm.h | 107 +++++++++ arch/arm64/kvm/hyp/include/nvhe/spinlock.h | 92 ++++++++ arch/arm64/kvm/hyp/nvhe/Makefile | 9 +- arch/arm64/kvm/hyp/nvhe/cache.S | 13 ++ arch/arm64/kvm/hyp/nvhe/cpufeature.c | 8 + arch/arm64/kvm/hyp/nvhe/early_alloc.c | 60 +++++ arch/arm64/kvm/hyp/nvhe/hyp-init.S | 41 ++++ arch/arm64/kvm/hyp/nvhe/hyp-main.c | 48 ++++ arch/arm64/kvm/hyp/nvhe/hyp.lds.S | 1 + arch/arm64/kvm/hyp/nvhe/mem_protect.c | 191 ++++++++++++++++ arch/arm64/kvm/hyp/nvhe/mm.c | 174 ++++++++++++++ arch/arm64/kvm/hyp/nvhe/page_alloc.c | 185 +++++++++++++++ arch/arm64/kvm/hyp/nvhe/psci-relay.c | 4 +- arch/arm64/kvm/hyp/nvhe/setup.c | 214 ++++++++++++++++++ arch/arm64/kvm/hyp/nvhe/stub.c | 22 ++ arch/arm64/kvm/hyp/nvhe/switch.c | 12 +- arch/arm64/kvm/hyp/nvhe/tlb.c | 4 +- arch/arm64/kvm/hyp/pgtable.c | 98 ++++---- arch/arm64/kvm/hyp/reserved_mem.c | 104 +++++++++ arch/arm64/kvm/mmu.c | 114 +++++++++- arch/arm64/kvm/reset.c | 42 +--- arch/arm64/lib/clear_page.S | 4 +- arch/arm64/lib/copy_page.S | 4 +- arch/arm64/mm/init.c | 3 + drivers/of/fdt.c | 5 + 45 files changed, 1954 insertions(+), 145 deletions(-) create mode 100644 arch/arm64/include/asm/kvm_cpufeature.h create mode 100644 arch/arm64/kvm/hyp/include/nvhe/early_alloc.h create mode 100644 arch/arm64/kvm/hyp/include/nvhe/gfp.h create mode 100644 arch/arm64/kvm/hyp/include/nvhe/mem_protect.h create mode 100644 arch/arm64/kvm/hyp/include/nvhe/memory.h create mode 100644 arch/arm64/kvm/hyp/include/nvhe/mm.h create mode 100644 arch/arm64/kvm/hyp/include/nvhe/spinlock.h create mode 100644 arch/arm64/kvm/hyp/nvhe/cache.S create mode 100644 arch/arm64/kvm/hyp/nvhe/cpufeature.c create mode 100644 arch/arm64/kvm/hyp/nvhe/early_alloc.c create mode 100644 arch/arm64/kvm/hyp/nvhe/mem_protect.c create mode 100644 arch/arm64/kvm/hyp/nvhe/mm.c create mode 100644 arch/arm64/kvm/hyp/nvhe/page_alloc.c create mode 100644 arch/arm64/kvm/hyp/nvhe/setup.c create mode 100644 arch/arm64/kvm/hyp/nvhe/stub.c create mode 100644 arch/arm64/kvm/hyp/reserved_mem.c