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

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Message-ID: <516BFB6C.2000303@siemens.com>
Date:	Mon, 15 Apr 2013 15:06:52 +0200
From:	Jan Kiszka <jan.kiszka@...mens.com>
To:	Paolo Bonzini <pbonzini@...hat.com>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"gnatapov@...hat.com" <gnatapov@...hat.com>,
	"kvm@...r.kernel.org" <kvm@...r.kernel.org>
Subject: Re: [PATCH v2] kvm: nVMX: check vmcs12 for valid activity state

On 2013-04-15 15:00, 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@...hat.com>
> ---
> 	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 =
> 

Reviewed-by: Jan Kiszka <jan.kiszka@...mens.com>

-- 
Siemens AG, Corporate Technology, CT RTC ITP SDP-DE
Corporate Competence Center Embedded Linux
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