diff options
| author |   Sean Christopherson <seanjc@google.com> | 2021-02-25 12:47:30 -0800 |
|---|---|---|
| committer |   Paolo Bonzini <pbonzini@redhat.com> | 2021-03-15 04:43:37 -0400 |
| commit | e0c378684b6545ad2d4403bb701d0ac4932b4e95 (patch) | |
| tree | 068e4c08fe76e6bac75b2e92a359f206940caa0d | |
| parent | KVM: x86/mmu: Disable MMIO caching if MMIO value collides with L1TF (diff) | |
KVM: x86/mmu: Retry page faults that hit an invalid memslot
Retry page faults (re-enter the guest) that hit an invalid memslot
instead of treating the memslot as not existing, i.e. handling the
page fault as an MMIO access. When deleting a memslot, SPTEs aren't
zapped and the TLBs aren't flushed until after the memslot has been
marked invalid.
Handling the invalid slot as MMIO means there's a small window where a
page fault could replace a valid SPTE with an MMIO SPTE. The legacy
MMU handles such a scenario cleanly, but the TDP MMU assumes such
behavior is impossible (see the BUG() in __handle_changed_spte()).
There's really no good reason why the legacy MMU should allow such a
scenario, and closing this hole allows for additional cleanups.
Fixes: 2f2fad0897cb ("kvm: x86/mmu: Add functions to handle changed TDP SPTEs")
Cc: Ben Gardon <bgardon@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210225204749.1512652-6-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
| -rw-r--r-- | arch/x86/kvm/mmu/mmu.c | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 474c2b6dbc9e..df75ebbf1b39 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -3683,6 +3683,14 @@ static bool try_async_pf(struct kvm_vcpu *vcpu, bool prefault, gfn_t gfn, struct kvm_memory_slot *slot = kvm_vcpu_gfn_to_memslot(vcpu, gfn); bool async; + /* + * Retry the page fault if the gfn hit a memslot that is being deleted + * or moved. This ensures any existing SPTEs for the old memslot will + * be zapped before KVM inserts a new MMIO SPTE for the gfn. + */ + if (slot && (slot->flags & KVM_MEMSLOT_INVALID)) + return true; + /* Don't expose private memslots to L2. */ if (is_guest_mode(vcpu) && !kvm_is_visible_memslot(slot)) { *pfn = KVM_PFN_NOSLOT; |