[PATCH] kvm:x86/svm: enable SVM lock if host supports it

[PATCH] kvm:x86/svm: enable SVM lock if host supports it

[prasadjoshi.linux]

From: Prasad Joshi <prasadjoshi.linux@gmail.com>

SVM lock features allows software from preventing update to EFER.SVME.
Enable the SVM lock in guest if it is supported on host machine.

Signed-off-by: Prasad Joshi <prasadjoshi.linux@gmail.com>
---
 arch/x86/kvm/svm.c |    4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index e1b1ce2..fcdfdea 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -4031,6 +4031,10 @@ static void svm_set_supported_cpuid(u32 func, struct kvm_cpuid_entry2 *entry)
 		if (boot_cpu_has(X86_FEATURE_NRIPS))
 			entry->edx |= SVM_FEATURE_NRIP;
 
+		/* support SVM Lock if host supports it */
+		if (boot_cpu_has(X86_FEATURE_SVML))
+			entry->edx |= SVM_FEATURE_SVML;
+
 		/* Support NPT for the guest if enabled */
 		if (npt_enabled)
 			entry->edx |= SVM_FEATURE_NPT;
-- 
1.7.10.4

Re: [PATCH] kvm:x86/svm: enable SVM lock if host supports it

[Joerg Roedel]

On Wed, Apr 17, 2013 at 11:03:33PM +0530, prasadjoshi.linux@gmail.com wrote:
> From: Prasad Joshi <prasadjoshi.linux@gmail.com>
> 
> SVM lock features allows software from preventing update to EFER.SVME.
> Enable the SVM lock in guest if it is supported on host machine.
> 
> Signed-off-by: Prasad Joshi <prasadjoshi.linux@gmail.com>
> ---
>  arch/x86/kvm/svm.c |    4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
> index e1b1ce2..fcdfdea 100644
> --- a/arch/x86/kvm/svm.c
> +++ b/arch/x86/kvm/svm.c
> @@ -4031,6 +4031,10 @@ static void svm_set_supported_cpuid(u32 func, struct kvm_cpuid_entry2 *entry)
>  		if (boot_cpu_has(X86_FEATURE_NRIPS))
>  			entry->edx |= SVM_FEATURE_NRIP;
>  
> +		/* support SVM Lock if host supports it */
> +		if (boot_cpu_has(X86_FEATURE_SVML))
> +			entry->edx |= SVM_FEATURE_SVML;
> +

No. SVM lock is way more complex to emulate than just setting the CPUID
bit.


	Joerg

Re: [PATCH] kvm:x86/svm: enable SVM lock if host supports it

[Prasad Joshi]

On Thu, Apr 18, 2013 at 1:18 AM, Joerg Roedel <joro@8bytes.org> wrote:
> On Wed, Apr 17, 2013 at 11:03:33PM +0530, prasadjoshi.linux@gmail.com wrote:
>> From: Prasad Joshi <prasadjoshi.linux@gmail.com>
>>
>> SVM lock features allows software from preventing update to EFER.SVME.
>> Enable the SVM lock in guest if it is supported on host machine.
>>
>> Signed-off-by: Prasad Joshi <prasadjoshi.linux@gmail.com>
>> ---
>>  arch/x86/kvm/svm.c |    4 ++++
>>  1 file changed, 4 insertions(+)
>>
>> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
>> index e1b1ce2..fcdfdea 100644
>> --- a/arch/x86/kvm/svm.c
>> +++ b/arch/x86/kvm/svm.c
>> @@ -4031,6 +4031,10 @@ static void svm_set_supported_cpuid(u32 func, struct kvm_cpuid_entry2 *entry)
>>               if (boot_cpu_has(X86_FEATURE_NRIPS))
>>                       entry->edx |= SVM_FEATURE_NRIP;
>>
>> +             /* support SVM Lock if host supports it */
>> +             if (boot_cpu_has(X86_FEATURE_SVML))
>> +                     entry->edx |= SVM_FEATURE_SVML;
>> +
>
> No. SVM lock is way more complex to emulate than just setting the CPUID
> bit.

Hello Joerg,

I suppose you meant, SVM_KEY MSR to lock/unlock the VM_CR.LOCK. If I
am correct, I just sent couple of patches. Can you please review them?

Thanks and Warm Regards,
Prasad

>
>
>         Joerg
>
>