diff options
| author | Zeng Chi <zengchi@kylinos.cn> | 2026-09-04 21:45:13 +0800 |
|---|---|---|
| committer | Huacai Chen <chenhuacai@loongson.cn> | 2026-09-04 21:45:13 +0800 |
| commit | 27a9bfee3bbcb3cabb77797354f07e0e44e49831 (patch) | |
| tree | 2acdc8fafa2e40a18b3b05e0d6193b79508ffe56 | |
| parent | 40bdbb4bfa730400e8b383d6f5931f90aebb5f54 (diff) | |
| download | linux-next-27a9bfee3bbcb3cabb77797354f07e0e44e49831.tar.gz linux-next-27a9bfee3bbcb3cabb77797354f07e0e44e49831.zip | |
LoongArch: KVM: Preserve memslot arch flags on KVM_MR_FLAGS_ONLY
kvm_arch_prepare_memory_region() computes new->arch.flags, i.e. whether
a memslot is KVM_MEM_HUGEPAGE_CAPABLE or KVM_MEM_HUGEPAGE_INCAPABLE,
only for KVM_MR_CREATE and KVM_MR_MOVE, and returns early for every
other change. But the generic code allocates a zeroed memslot for every
change and never copies old->arch, so after a KVM_MR_FLAGS_ONLY update,
e.g. toggling KVM_MEM_LOG_DIRTY_PAGES for live migration, the active
memslot has arch.flags == 0.
With both flags clear, fault_supports_huge_mapping() falls through to
the alignment check on the HVA range alone, which no longer verifies
that the GPA and HVA have the same offset within a PMD. A memslot that
was marked KVM_MEM_HUGEPAGE_INCAPABLE because of a GPA/HVA offset
mismatch can then be mapped with PMD entries on read faults, and since
kvm_map_page() aligns the gfn and the pfn independently, the guest ends
up accessing the wrong host pages, exactly the "d -> f, e -> g" case
described in the comment above the check.
Carry the arch flags over from the old memslot for KVM_MR_FLAGS_ONLY,
as the GPA, HVA and size are guaranteed to be unchanged for that case.
Cc: stable@vger.kernel.org
Fixes: 7ab6fb505b2a ("LoongArch: KVM: Optimization for memslot hugepage checking")
Tested-by: Tao Cui <cuitao@kylinos.cn>
Reviewed-by: Tao Cui <cuitao@kylinos.cn>
Reviewed-by: Bibo Mao <maobibo@loongson.cn>
Signed-off-by: Zeng Chi <zengchi@kylinos.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
| -rw-r--r-- | arch/loongarch/kvm/mmu.c | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/arch/loongarch/kvm/mmu.c b/arch/loongarch/kvm/mmu.c index 2c08402bfd3e..3e9a0b285fd2 100644 --- a/arch/loongarch/kvm/mmu.c +++ b/arch/loongarch/kvm/mmu.c @@ -383,6 +383,16 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm, const struct kvm_memory_slot hva_t hva_start; size_t size, gpa_offset, hva_offset; + /* + * The generic code allocates a fresh, zeroed memslot for every change, + * so the arch flags computed below must be carried over when only the + * userspace flags change, e.g. when dirty logging is toggled. + */ + if (change == KVM_MR_FLAGS_ONLY) { + new->arch = old->arch; + return 0; + } + if ((change != KVM_MR_MOVE) && (change != KVM_MR_CREATE)) return 0; /* |