diff options
| author | Sean Christopherson <seanjc@google.com> | 2021-02-25 23:47:48 +0300 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2021-03-15 11:43:54 +0300 |
| commit | 715f1079eee12f629b2de5c8a9489124a5af0a18 (patch) | |
| tree | 531f1f6c35c82a6f18bf0287baf2a54c0a226984 /arch/x86/kvm/mmu/spte.c | |
| parent | 7a51393ae0f6287f9b2bdd138f5a091b7c302c1f (diff) | |
KVM: x86/mmu: Use low available bits for removed SPTEs
Use low "available" bits to tag REMOVED SPTEs. Using a high bit is
moderately costly as it often causes the compiler to generate a 64-bit
immediate. More importantly, this makes it very clear REMOVED_SPTE is
a value, not a flag.
Cc: Ben Gardon <bgardon@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210225204749.1512652-24-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86/kvm/mmu/spte.c')
| -rw-r--r-- | arch/x86/kvm/mmu/spte.c | 11 |
1 files changed, 10 insertions, 1 deletions
diff --git a/arch/x86/kvm/mmu/spte.c b/arch/x86/kvm/mmu/spte.c index e07aabb23b8a..66d43cec0c31 100644 --- a/arch/x86/kvm/mmu/spte.c +++ b/arch/x86/kvm/mmu/spte.c @@ -277,7 +277,16 @@ void kvm_mmu_set_mmio_spte_mask(u64 mmio_value, u64 mmio_mask, u64 access_mask) SHADOW_NONPRESENT_OR_RSVD_MASK_LEN))) mmio_value = 0; - WARN_ON((mmio_value & mmio_mask) != mmio_value); + /* + * The masked MMIO value must obviously match itself and a removed SPTE + * must not get a false positive. Removed SPTEs and MMIO SPTEs should + * never collide as MMIO must set some RWX bits, and removed SPTEs must + * not set any RWX bits. + */ + if (WARN_ON((mmio_value & mmio_mask) != mmio_value) || + WARN_ON(mmio_value && (REMOVED_SPTE & mmio_mask) == mmio_value)) + mmio_value = 0; + shadow_mmio_value = mmio_value; shadow_mmio_mask = mmio_mask; shadow_mmio_access_mask = access_mask; |