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| author |   Sean Christopherson <seanjc@google.com> | 2024-10-10 19:10:40 -0700 |
|---|---|---|
| committer | Sean Christopherson <seanjc@google.com> | 2024-10-30 14:46:46 -0700 |
| commit | 1a175082b190190d9d05a0a5927b72cbb657fd1d (patch) | |
| tree | e064f9a77da38f3705364ff4f026b639c707c05c | |
| parent | KVM: x86/mmu: Fold mmu_spte_update_no_track() into mmu_spte_update() (diff) | |
| download | wireguard-linux-1a175082b190190d9d05a0a5927b72cbb657fd1d.tar.xz wireguard-linux-1a175082b190190d9d05a0a5927b72cbb657fd1d.zip | |
KVM: x86/mmu: WARN and flush if resolving a TDP MMU fault clears MMU-writable
Do a remote TLB flush if installing a leaf SPTE overwrites an existing
leaf SPTE (with the same target pfn, which is enforced by a BUG() in
handle_changed_spte()) and clears the MMU-Writable bit. Since the TDP MMU
passes ACC_ALL to make_spte(), i.e. always requests a Writable SPTE, the
only scenario in which make_spte() should create a !MMU-Writable SPTE is
if the gfn is write-tracked or if KVM is prefetching a SPTE.
When write-protecting for write-tracking, KVM must hold mmu_lock for write,
i.e. can't race with a vCPU faulting in the SPTE. And when prefetching a
SPTE, the TDP MMU takes care to avoid clobbering a shadow-present SPTE,
i.e. it should be impossible to replace a MMU-writable SPTE with a
!MMU-writable SPTE when handling a TDP MMU fault.
Cc: David Matlack <dmatlack@google.com>
Cc: Yan Zhao <yan.y.zhao@intel.com>
Link: https://lore.kernel.org/r/20241011021051.1557902-9-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Diffstat (limited to '')
| -rw-r--r-- | arch/x86/kvm/mmu/tdp_mmu.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c index 9c66be7fb002..bc9e2f50dc80 100644 --- a/arch/x86/kvm/mmu/tdp_mmu.c +++ b/arch/x86/kvm/mmu/tdp_mmu.c @@ -1033,7 +1033,9 @@ static int tdp_mmu_map_handle_target_level(struct kvm_vcpu *vcpu, else if (tdp_mmu_set_spte_atomic(vcpu->kvm, iter, new_spte)) return RET_PF_RETRY; else if (is_shadow_present_pte(iter->old_spte) && - !is_last_spte(iter->old_spte, iter->level)) + (!is_last_spte(iter->old_spte, iter->level) || + WARN_ON_ONCE(is_mmu_writable_spte(iter->old_spte) && + !is_mmu_writable_spte(new_spte)))) kvm_flush_remote_tlbs_gfn(vcpu->kvm, iter->gfn, iter->level); /* |