1 files changed, 40 insertions, 3 deletions

diff --git a/arch/x86/kvm/mmu/spte.c b/arch/x86/kvm/mmu/spte.c
index cfce03d8f123..df31039b5d63 100644
--- a/arch/x86/kvm/mmu/spte.c
+++ b/arch/x86/kvm/mmu/spte.c
@@ -104,7 +104,7 @@ u64 make_mmio_spte(struct kvm_vcpu *vcpu, u64 gfn, unsigned int access)
 	return spte;
 }
 
-static bool kvm_is_mmio_pfn(kvm_pfn_t pfn)
+static bool __kvm_is_mmio_pfn(kvm_pfn_t pfn)
 {
 	if (pfn_valid(pfn))
 		return !is_zero_pfn(pfn) && PageReserved(pfn_to_page(pfn)) &&
@@ -125,6 +125,35 @@ static bool kvm_is_mmio_pfn(kvm_pfn_t pfn)
 				     E820_TYPE_RAM);
 }
 
+static bool kvm_is_mmio_pfn(kvm_pfn_t pfn, int *is_host_mmio)
+{
+	/*
+	 * Determining if a PFN is host MMIO is relative expensive.  Cache the
+	 * result locally (in the sole caller) to avoid doing the full query
+	 * multiple times when creating a single SPTE.
+	 */
+	if (*is_host_mmio < 0)
+		*is_host_mmio = __kvm_is_mmio_pfn(pfn);
+
+	return *is_host_mmio;
+}
+
+static void kvm_track_host_mmio_mapping(struct kvm_vcpu *vcpu)
+{
+	struct kvm_mmu_page *root = root_to_sp(vcpu->arch.mmu->root.hpa);
+
+	if (root)
+		WRITE_ONCE(root->has_mapped_host_mmio, true);
+	else
+		WRITE_ONCE(vcpu->kvm->arch.has_mapped_host_mmio, true);
+
+	/*
+	 * Force vCPUs to exit and flush CPU buffers if the vCPU is using the
+	 * affected root(s).
+	 */
+	kvm_make_all_cpus_request(vcpu->kvm, KVM_REQ_OUTSIDE_GUEST_MODE);
+}
+
 /*
  * Returns true if the SPTE needs to be updated atomically due to having bits
  * that may be changed without holding mmu_lock, and for which KVM must not
@@ -162,6 +191,7 @@ bool make_spte(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
 {
 	int level = sp->role.level;
 	u64 spte = SPTE_MMU_PRESENT_MASK;
+	int is_host_mmio = -1;
 	bool wrprot = false;
 
 	/*
@@ -209,13 +239,15 @@ bool make_spte(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
 	if (level > PG_LEVEL_4K)
 		spte |= PT_PAGE_SIZE_MASK;
 
-	spte |= kvm_x86_call(get_mt_mask)(vcpu, gfn, kvm_is_mmio_pfn(pfn));
+	if (kvm_x86_ops.get_mt_mask)
+		spte |= kvm_x86_call(get_mt_mask)(vcpu, gfn,
+						  kvm_is_mmio_pfn(pfn, &is_host_mmio));
 	if (host_writable)
 		spte |= shadow_host_writable_mask;
 	else
 		pte_access &= ~ACC_WRITE_MASK;
 
-	if (shadow_me_value && !kvm_is_mmio_pfn(pfn))
+	if (shadow_me_value && !kvm_is_mmio_pfn(pfn, &is_host_mmio))
 		spte |= shadow_me_value;
 
 	spte |= (u64)pfn << PAGE_SHIFT;
@@ -260,6 +292,11 @@ bool make_spte(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
 		mark_page_dirty_in_slot(vcpu->kvm, slot, gfn);
 	}
 
+	if (static_branch_unlikely(&cpu_buf_vm_clear) &&
+	    !kvm_vcpu_can_access_host_mmio(vcpu) &&
+	    kvm_is_mmio_pfn(pfn, &is_host_mmio))
+		kvm_track_host_mmio_mapping(vcpu);
+
 	*new_spte = spte;
 	return wrprot;
 }