diff options
author | Oliver Upton <oliver.upton@linux.dev> | 2023-06-28 02:54:05 +0300 |
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committer | Oliver Upton <oliver.upton@linux.dev> | 2023-07-12 23:10:40 +0300 |
commit | df6556adf27b7372cfcd97e1c0afb0d516c8279f (patch) | |
tree | 8f0da1e0576081ebf5ebae2cab8a272892592bc0 /arch/arm64/include/asm/kvm_pgtable.h | |
parent | 970dee09b230895fe2230d2b32ad05a2826818c6 (diff) | |
download | linux-df6556adf27b7372cfcd97e1c0afb0d516c8279f.tar.xz |
KVM: arm64: Correctly handle page aging notifiers for unaligned memslot
Userspace is allowed to select any PAGE_SIZE aligned hva to back guest
memory. This is even the case with hugepages, although it is a rather
suboptimal configuration as PTE level mappings are used at stage-2.
The arm64 page aging handlers have an assumption that the specified
range is exactly one page/block of memory, which in the aforementioned
case is not necessarily true. All together this leads to the WARN() in
kvm_age_gfn() firing.
However, the WARN is only part of the issue as the table walkers visit
at most a single leaf PTE. For hugepage-backed memory in a memslot that
isn't hugepage-aligned, page aging entirely misses accesses to the
hugepage beyond the first page in the memslot.
Add a new walker dedicated to handling page aging MMU notifiers capable
of walking a range of PTEs. Convert kvm(_test)_age_gfn() over to the new
walker and drop the WARN that caught the issue in the first place. The
implementation of this walker was inspired by the test_clear_young()
implementation by Yu Zhao [*], but repurposed to address a bug in the
existing aging implementation.
Cc: stable@vger.kernel.org # v5.15
Fixes: 056aad67f836 ("kvm: arm/arm64: Rework gpa callback handlers")
Link: https://lore.kernel.org/kvmarm/20230526234435.662652-6-yuzhao@google.com/
Co-developed-by: Yu Zhao <yuzhao@google.com>
Signed-off-by: Yu Zhao <yuzhao@google.com>
Reported-by: Reiji Watanabe <reijiw@google.com>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Shaoqin Huang <shahuang@redhat.com>
Link: https://lore.kernel.org/r/20230627235405.4069823-1-oliver.upton@linux.dev
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
Diffstat (limited to 'arch/arm64/include/asm/kvm_pgtable.h')
-rw-r--r-- | arch/arm64/include/asm/kvm_pgtable.h | 26 |
1 files changed, 9 insertions, 17 deletions
diff --git a/arch/arm64/include/asm/kvm_pgtable.h b/arch/arm64/include/asm/kvm_pgtable.h index 8294a9a7e566..929d355eae0a 100644 --- a/arch/arm64/include/asm/kvm_pgtable.h +++ b/arch/arm64/include/asm/kvm_pgtable.h @@ -608,22 +608,26 @@ int kvm_pgtable_stage2_wrprotect(struct kvm_pgtable *pgt, u64 addr, u64 size); kvm_pte_t kvm_pgtable_stage2_mkyoung(struct kvm_pgtable *pgt, u64 addr); /** - * kvm_pgtable_stage2_mkold() - Clear the access flag in a page-table entry. + * kvm_pgtable_stage2_test_clear_young() - Test and optionally clear the access + * flag in a page-table entry. * @pgt: Page-table structure initialised by kvm_pgtable_stage2_init*(). * @addr: Intermediate physical address to identify the page-table entry. + * @size: Size of the address range to visit. + * @mkold: True if the access flag should be cleared. * * The offset of @addr within a page is ignored. * - * If there is a valid, leaf page-table entry used to translate @addr, then - * clear the access flag in that entry. + * Tests and conditionally clears the access flag for every valid, leaf + * page-table entry used to translate the range [@addr, @addr + @size). * * Note that it is the caller's responsibility to invalidate the TLB after * calling this function to ensure that the updated permissions are visible * to the CPUs. * - * Return: The old page-table entry prior to clearing the flag, 0 on failure. + * Return: True if any of the visited PTEs had the access flag set. */ -kvm_pte_t kvm_pgtable_stage2_mkold(struct kvm_pgtable *pgt, u64 addr); +bool kvm_pgtable_stage2_test_clear_young(struct kvm_pgtable *pgt, u64 addr, + u64 size, bool mkold); /** * kvm_pgtable_stage2_relax_perms() - Relax the permissions enforced by a @@ -646,18 +650,6 @@ int kvm_pgtable_stage2_relax_perms(struct kvm_pgtable *pgt, u64 addr, enum kvm_pgtable_prot prot); /** - * kvm_pgtable_stage2_is_young() - Test whether a page-table entry has the - * access flag set. - * @pgt: Page-table structure initialised by kvm_pgtable_stage2_init*(). - * @addr: Intermediate physical address to identify the page-table entry. - * - * The offset of @addr within a page is ignored. - * - * Return: True if the page-table entry has the access flag set, false otherwise. - */ -bool kvm_pgtable_stage2_is_young(struct kvm_pgtable *pgt, u64 addr); - -/** * kvm_pgtable_stage2_flush_range() - Clean and invalidate data cache to Point * of Coherency for guest stage-2 address * range. |