diff mbox

[v2,1/2] kvm: nVMX: Restrict VMX capability MSR changes

Message ID 20180529161133.206604-1-jmattson@google.com (mailing list archive)
State New, archived
Headers show

Commit Message

Jim Mattson May 29, 2018, 4:11 p.m. UTC 
Disallow changes to the VMX capability MSRs while the vCPU is in VMX
operation. Although this does break the existing API, it helps to
avoid some potentially tricky situations for which there is no
architected behavior.

Signed-off-by: Jim Mattson <jmattson@google.com>
---
 arch/x86/kvm/vmx.c | 7 +++++++
 1 file changed, 7 insertions(+)

Comments

Krish Sadhukhan May 30, 2018, 5:14 p.m. UTC | #1 
On 05/29/2018 09:11 AM, Jim Mattson wrote:
> Disallow changes to the VMX capability MSRs while the vCPU is in VMX
> operation. Although this does break the existing API, it helps to
> avoid some potentially tricky situations for which there is no
> architected behavior.
>
> Signed-off-by: Jim Mattson <jmattson@google.com>
> ---
>   arch/x86/kvm/vmx.c | 7 +++++++
>   1 file changed, 7 insertions(+)
>
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index e50beb76d846..5ea57442fef9 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -3538,6 +3538,13 @@ static int vmx_set_vmx_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 data)
>   {
>   	struct vcpu_vmx *vmx = to_vmx(vcpu);
>   
> +	/*
> +	 * Don't allow changes to the VMX capability MSRs while the vCPU
> +	 * is in VMX operation.
> +	 */
> +	if (vmx->nested.vmxon)
> +		return -EBUSY;
> +
>   	switch (msr_index) {
>   	case MSR_IA32_VMX_BASIC:
>   		return vmx_restore_vmx_basic(vmx, data);
This check can be placed right in vmx_set_msr():

                         if (!nested_vmx_allowed(vcpu)  || 
(vmx->nested.vmxon))
                                 return 1;

Other than that,

Reviewed-by: Krish Sadhukhan <krish.sadhukhan@oracle.com>
diff mbox

Patch

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index e50beb76d846..5ea57442fef9 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -3538,6 +3538,13 @@  static int vmx_set_vmx_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 data)
 {
 	struct vcpu_vmx *vmx = to_vmx(vcpu);
 
+	/*
+	 * Don't allow changes to the VMX capability MSRs while the vCPU
+	 * is in VMX operation.
+	 */
+	if (vmx->nested.vmxon)
+		return -EBUSY;
+
 	switch (msr_index) {
 	case MSR_IA32_VMX_BASIC:
 		return vmx_restore_vmx_basic(vmx, data);