kvm: vmx: Flush TLB when the APIC-access address changes

Quoting from the Intel SDM, volume 3, section 28.3.3.4: Guidelines for
Use of the INVEPT Instruction:

If EPT was in use on a logical processor at one time with EPTP X, it
is recommended that software use the INVEPT instruction with the
"single-context" INVEPT type and with EPTP X in the INVEPT descriptor
before a VM entry on the same logical processor that enables EPT with
EPTP X and either (a) the "virtualize APIC accesses" VM-execution
control was changed from 0 to 1; or (b) the value of the APIC-access
address was changed.

In the nested case, the burden falls on L1, unless L0 enables EPT in
vmcs02 when L1 doesn't enable EPT in vmcs12.

Signed-off-by: Jim Mattson <jmattson@google.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index c664365..e2f6082 100644 (file)
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -4024,6 +4024,12 @@ static void vmx_flush_tlb(struct kvm_vcpu *vcpu)
        __vmx_flush_tlb(vcpu, to_vmx(vcpu)->vpid);
 }
 
+static void vmx_flush_tlb_ept_only(struct kvm_vcpu *vcpu)
+{
+       if (enable_ept)
+               vmx_flush_tlb(vcpu);
+}
+
 static void vmx_decache_cr0_guest_bits(struct kvm_vcpu *vcpu)
 {
        ulong cr0_guest_owned_bits = vcpu->arch.cr0_guest_owned_bits;
@@ -8548,6 +8554,7 @@ static void vmx_set_virtual_x2apic_mode(struct kvm_vcpu *vcpu, bool set)
        } else {
                sec_exec_control &= ~SECONDARY_EXEC_VIRTUALIZE_X2APIC_MODE;
                sec_exec_control |= SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES;
+               vmx_flush_tlb_ept_only(vcpu);
        }
        vmcs_write32(SECONDARY_VM_EXEC_CONTROL, sec_exec_control);
 
@@ -8573,8 +8580,10 @@ static void vmx_set_apic_access_page_addr(struct kvm_vcpu *vcpu, hpa_t hpa)
         */
        if (!is_guest_mode(vcpu) ||
            !nested_cpu_has2(get_vmcs12(&vmx->vcpu),
-                            SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES))
+                            SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES)) {
                vmcs_write64(APIC_ACCESS_ADDR, hpa);
+               vmx_flush_tlb_ept_only(vcpu);
+       }
 }
 
 static void vmx_hwapic_isr_update(struct kvm_vcpu *vcpu, int max_isr)
@@ -10256,6 +10265,9 @@ static int prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12,
        if (nested_cpu_has_ept(vmcs12)) {
                kvm_mmu_unload(vcpu);
                nested_ept_init_mmu_context(vcpu);
+       } else if (nested_cpu_has2(vmcs12,
+                                  SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES)) {
+               vmx_flush_tlb_ept_only(vcpu);
        }
 
        /*
@@ -11055,6 +11067,10 @@ static void nested_vmx_vmexit(struct kvm_vcpu *vcpu, u32 exit_reason,
                vmx->nested.change_vmcs01_virtual_x2apic_mode = false;
                vmx_set_virtual_x2apic_mode(vcpu,
                                vcpu->arch.apic_base & X2APIC_ENABLE);
+       } else if (!nested_cpu_has_ept(vmcs12) &&
+                  nested_cpu_has2(vmcs12,
+                                  SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES)) {
+               vmx_flush_tlb_ept_only(vcpu);
        }
 
        /* This is needed for same reason as it was needed in prepare_vmcs02 */