diff options
| author | Yan Zhao <yan.y.zhao@intel.com> | 2025-03-18 04:31:11 +0300 |
|---|---|---|
| committer | Sean Christopherson <seanjc@google.com> | 2025-04-28 21:03:06 +0300 |
| commit | ea9fcdf76d3d1d659fb3daaa0cca7b1f4a0697bc (patch) | |
| tree | 1bd069691be1269e4194440be2391075208ee517 | |
| parent | 45eb29140e68ffe8e93a5471006858a018480a45 (diff) | |
| download | linux-ea9fcdf76d3d1d659fb3daaa0cca7b1f4a0697bc.tar.xz | |
KVM: x86/mmu: Further check old SPTE is leaf for spurious prefetch fault
Instead of simply treating a prefetch fault as spurious when there's a
shadow-present old SPTE, further check if the old SPTE is leaf to determine
if a prefetch fault is spurious.
It's not reasonable to treat a prefetch fault as spurious when there's a
shadow-present non-leaf SPTE without a corresponding shadow-present leaf
SPTE. e.g., in the following sequence, a prefetch fault should not be
considered spurious:
1. add a memslot with size 4K
2. prefault GPA A in the memslot
3. delete the memslot (zap all disabled)
4. re-add the memslot with size 2M
5. prefault GPA A again.
In step 5, the prefetch fault attempts to install a 2M huge entry.
Since step 3 zaps the leaf SPTE for GPA A while keeping the non-leaf SPTE,
the leaf entry will remain empty after step 5 if the fetch fault is
regarded as spurious due to a shadow-present non-leaf SPTE.
Signed-off-by: Yan Zhao <yan.y.zhao@intel.com>
Link: https://lore.kernel.org/r/20250318013111.5648-1-yan.y.zhao@intel.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
| -rw-r--r-- | arch/x86/kvm/mmu/mmu.c | 2 | ||||
| -rw-r--r-- | arch/x86/kvm/mmu/tdp_mmu.c | 3 |
2 files changed, 3 insertions, 2 deletions
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index a284dce227a0..b50d9e715806 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -3020,7 +3020,7 @@ static int mmu_set_spte(struct kvm_vcpu *vcpu, struct kvm_memory_slot *slot, } if (is_shadow_present_pte(*sptep)) { - if (prefetch) + if (prefetch && is_last_spte(*sptep, level)) return RET_PF_SPURIOUS; /* diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c index 405874f4d088..f53402257217 100644 --- a/arch/x86/kvm/mmu/tdp_mmu.c +++ b/arch/x86/kvm/mmu/tdp_mmu.c @@ -1153,7 +1153,8 @@ static int tdp_mmu_map_handle_target_level(struct kvm_vcpu *vcpu, if (WARN_ON_ONCE(sp->role.level != fault->goal_level)) return RET_PF_RETRY; - if (fault->prefetch && is_shadow_present_pte(iter->old_spte)) + if (fault->prefetch && is_shadow_present_pte(iter->old_spte) && + is_last_spte(iter->old_spte, iter->level)) return RET_PF_SPURIOUS; if (is_shadow_present_pte(iter->old_spte) && |