KVM: nVMX: Do not mark vmcs02->apic_access_page as dirty when unpinning

vmcs->apic_access_page is simply a token that the hypervisor puts into
the PFN of a 4KB EPTE (or PTE if using shadow-paging) that triggers
APIC-access VMExit or APIC virtualization logic whenever a CPU running
in VMX non-root mode read/write from/to this PFN.

As every write either triggers an APIC-access VMExit or write is
performed on vmcs->virtual_apic_page, the PFN pointed to by
vmcs->apic_access_page should never actually be touched by CPU.

Therefore, there is no need to mark vmcs02->apic_access_page as dirty
after unpin it on L2->L1 emulated VMExit or when L1 exit VMX operation.

Reviewed-by: Krish Sadhukhan <[email protected]>
Reviewed-by: Joao Martins <[email protected]>
Reviewed-by: Jim Mattson <[email protected]>
Signed-off-by: Liran Alon <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>

Author: Liran Alon

arch/x86/kvm/vmx/nested.c

@@ -268,7 +268,7 @@ static void free_nested(struct kvm_vcpu *vcpu)
 	vmx->nested.cached_shadow_vmcs12 = NULL;
 	/* Unpin physical memory we referred to in the vmcs02 */
 	if (vmx->nested.apic_access_page) {
-		kvm_release_page_dirty(vmx->nested.apic_access_page);
+		kvm_release_page_clean(vmx->nested.apic_access_page);
 		vmx->nested.apic_access_page = NULL;
 	}
 	kvm_vcpu_unmap(vcpu, &vmx->nested.virtual_apic_map, true);
@@ -3070,7 +3070,7 @@ static bool nested_get_vmcs12_pages(struct kvm_vcpu *vcpu)
 		 * to it so we can release it later.
 		 */
 		if (vmx->nested.apic_access_page) { /* shouldn't happen */
-			kvm_release_page_dirty(vmx->nested.apic_access_page);
+			kvm_release_page_clean(vmx->nested.apic_access_page);
 			vmx->nested.apic_access_page = NULL;
 		}
 		page = kvm_vcpu_gpa_to_page(vcpu, vmcs12->apic_access_addr);
@@ -4267,7 +4267,7 @@ void nested_vmx_vmexit(struct kvm_vcpu *vcpu, u32 exit_reason,
 
 	/* Unpin physical memory we referred to in vmcs02 */
 	if (vmx->nested.apic_access_page) {
-		kvm_release_page_dirty(vmx->nested.apic_access_page);
+		kvm_release_page_clean(vmx->nested.apic_access_page);
 		vmx->nested.apic_access_page = NULL;
 	}
 	kvm_vcpu_unmap(vcpu, &vmx->nested.virtual_apic_map, true);