Re: [PATCH] KVM: x86: Save&restore interrupt shadow mask

[Jan Kiszka <jan.kiszka@web.de>]

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Avi Kivity wrote:
> On 02/14/2010 06:49 PM, Jan Kiszka wrote:
>> From: Jan Kiszka<jan.kiszka@siemens.com>
>>
>> The interrupt shadow created by STI or MOV-SS-like operations is part of
>> the VCPU state and must be preserved across migration. Transfer it in
>> the spare padding field of kvm_vcpu_events.interrupt.
>>
>> As a side effect we now have to make vmx_set_interrupt_shadow robust
>> against both shadow types being set. Give MOV SS a higher priority and
>> skip STI in that case to avoid that VMX throws a fault on next entry.
>>
>>
>> diff --git a/arch/x86/include/asm/kvm.h b/arch/x86/include/asm/kvm.h
>> index f46b79f..4dd01e2 100644
>> --- a/arch/x86/include/asm/kvm.h
>> +++ b/arch/x86/include/asm/kvm.h
>> @@ -258,6 +258,9 @@ struct kvm_reinject_control {
>>   #define KVM_VCPUEVENT_VALID_NMI_PENDING    0x00000001
>>   #define KVM_VCPUEVENT_VALID_SIPI_VECTOR    0x00000002
>>
>> +#define X86_SHADOW_INT_MOV_SS  1
>> +#define X86_SHADOW_INT_STI     2
>> +
>>    
> 
> svm doesn't make a difference.  Is it worth exposing this to userspace
> (and thus providing wrong information on svm)?

SVM already folds both reasons into one. Don't know if we should do it
at the generic layer already - probably.

> 
> (in any case, needs a KVM_ prefix).

...and then this is no longer required. OK, will export this with
boolean meaning.

> 
> Needs a KVM_CAP_ and flags bit.

Why if merged before 2.6.33? We haven't released KVM_CAP_VCPU_EVENTS yet.

Jan


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