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authorSean Christopherson <seanjc@google.com>2024-02-27 18:41:40 -0800
committerPaolo Bonzini <pbonzini@redhat.com>2024-05-07 11:59:20 -0400
commit44f42ef37deb49682abf0108bf9ede88d4478a20 (patch)
treedbeaea1eca828ca7b2afba9047ed31c33d1e6b82 /arch/x86/kvm
parent07702e5a6d6d62266e5f156f23b00a272af64c8e (diff)
KVM: x86/mmu: Move private vs. shared check above slot validity checks
Prioritize private vs. shared gfn attribute checks above slot validity checks to ensure a consistent userspace ABI. E.g. as is, KVM will exit to userspace if there is no memslot, but emulate accesses to the APIC access page even if the attributes mismatch. Fixes: 8dd2eee9d526 ("KVM: x86/mmu: Handle page fault for private memory") Cc: Yu Zhang <yu.c.zhang@linux.intel.com> Cc: Chao Peng <chao.p.peng@linux.intel.com> Cc: Fuad Tabba <tabba@google.com> Cc: Michael Roth <michael.roth@amd.com> Cc: Isaku Yamahata <isaku.yamahata@intel.com> Signed-off-by: Sean Christopherson <seanjc@google.com> Reviewed-by: Kai Huang <kai.huang@intel.com> Message-ID: <20240228024147.41573-10-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86/kvm')
-rw-r--r--arch/x86/kvm/mmu/mmu.c20
1 files changed, 15 insertions, 5 deletions
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 9560fca3a6cf..c5546cd7e1b9 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -4316,11 +4316,6 @@ static int __kvm_faultin_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault
return RET_PF_EMULATE;
}
- if (fault->is_private != kvm_mem_is_private(vcpu->kvm, fault->gfn)) {
- kvm_mmu_prepare_memory_fault_exit(vcpu, fault);
- return -EFAULT;
- }
-
if (fault->is_private)
return kvm_faultin_pfn_private(vcpu, fault);
@@ -4358,10 +4353,25 @@ static int kvm_faultin_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault,
{
int ret;
+ /*
+ * Note that the mmu_invalidate_seq also serves to detect a concurrent
+ * change in attributes. is_page_fault_stale() will detect an
+ * invalidation relate to fault->fn and resume the guest without
+ * installing a mapping in the page tables.
+ */
fault->mmu_seq = vcpu->kvm->mmu_invalidate_seq;
smp_rmb();
/*
+ * Now that we have a snapshot of mmu_invalidate_seq we can check for a
+ * private vs. shared mismatch.
+ */
+ if (fault->is_private != kvm_mem_is_private(vcpu->kvm, fault->gfn)) {
+ kvm_mmu_prepare_memory_fault_exit(vcpu, fault);
+ return -EFAULT;
+ }
+
+ /*
* Check for a relevant mmu_notifier invalidation event before getting
* the pfn from the primary MMU, and before acquiring mmu_lock.
*