Re: [PATCH v2] kvm: nVMX: check vmcs12 for valid activity state

From: Gleb Natapov
Date: Mon Apr 15 2013 - 11:10:27 EST


On Mon, Apr 15, 2013 at 03:00:27PM +0200, Paolo Bonzini wrote:
> KVM does not use the activity state VMCS field, and does not support
> it in nested VMX either (the corresponding bits in the misc VMX feature
> MSR are zero). Fail entry if the activity state is set to anything but
> "active".
>
> Since the value will always be the same for L1 and L2, we do not need
> to read and write the corresponding VMCS field on L1/L2 transitions,
> either.
>
> Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Perfect, thanks!

Reviewed-by: Gleb Natapov <gleb@xxxxxxxxxx>

> ---
> v1->v2: remove read/write of vmcs12->guest_activity_state,
> use GUEST_ACTIVITY_ACTIVE.
>
> arch/x86/kvm/vmx.c | 7 +++++--
> 1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index c75c25d..c252adf 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -7004,7 +7004,6 @@ static void prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12)
> vmcs12->vm_entry_instruction_len);
> vmcs_write32(GUEST_INTERRUPTIBILITY_INFO,
> vmcs12->guest_interruptibility_info);
> - vmcs_write32(GUEST_ACTIVITY_STATE, vmcs12->guest_activity_state);
> vmcs_write32(GUEST_SYSENTER_CS, vmcs12->guest_sysenter_cs);
> kvm_set_dr(vcpu, 7, vmcs12->guest_dr7);
> vmcs_writel(GUEST_RFLAGS, vmcs12->guest_rflags);
> @@ -7223,6 +7222,11 @@ static int nested_vmx_run(struct kvm_vcpu *vcpu, bool launch)
> return 1;
> }
>
> + if (vmcs12->guest_activity_state != GUEST_ACTIVITY_ACTIVE) {
> + nested_vmx_failValid(vcpu, VMXERR_ENTRY_INVALID_CONTROL_FIELD);
> + return 1;
> + }
> +
> if ((vmcs12->cpu_based_vm_exec_control & CPU_BASED_USE_MSR_BITMAPS) &&
> !IS_ALIGNED(vmcs12->msr_bitmap, PAGE_SIZE)) {
> /*TODO: Also verify bits beyond physical address width are 0*/
> @@ -7411,7 +7415,6 @@ static void prepare_vmcs12(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12)
> vmcs12->guest_gdtr_base = vmcs_readl(GUEST_GDTR_BASE);
> vmcs12->guest_idtr_base = vmcs_readl(GUEST_IDTR_BASE);
>
> - vmcs12->guest_activity_state = vmcs_read32(GUEST_ACTIVITY_STATE);
> vmcs12->guest_interruptibility_info =
> vmcs_read32(GUEST_INTERRUPTIBILITY_INFO);
> vmcs12->guest_pending_dbg_exceptions =
> --
> 1.8.1.4

--
Gleb.
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