lkml.org 
[lkml]   [2018]   [Mar]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [PATCH 2/3] KVM: X86: Provides userspace with a capability to not intercept HLT
2018-03-09 4:40 GMT+08:00 Radim Krčmář <rkrcmar@redhat.com>:
> 2018-03-01 17:49+0800, Wanpeng Li:
>> From: Wanpeng Li <wanpengli@tencent.com>
>>
>> If host CPUs are dedicated to a VM, we can avoid VM exits on HLT.
>> This patch adds the per-VM non-HLT-exiting capability.
>>
>> Cc: Paolo Bonzini <pbonzini@redhat.com>
>> Cc: Radim Krčmář <rkrcmar@redhat.com>
>> Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
>> ---
>> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
>> index dff3a5d..fcf8339 100644
>> --- a/arch/x86/kvm/svm.c
>> +++ b/arch/x86/kvm/svm.c
>> @@ -1394,6 +1394,9 @@ static void init_vmcb(struct vcpu_svm *svm)
>> set_intercept(svm, INTERCEPT_MWAIT);
>> }
>>
>> + if (!kvm_hlt_in_guest(svm->vcpu.kvm))
>> + set_intercept(svm, INTERCEPT_HLT);
>
> We unconditionally set INTERCEPT_HLT just above, so that line has to be
> removed.

Agreed.

>
>> +
>> control->iopm_base_pa = __sme_set(iopm_base);
>> control->msrpm_base_pa = __sme_set(__pa(svm->msrpm));
>> control->int_ctl = V_INTR_MASKING_MASK;
>> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
>> @@ -2525,6 +2525,19 @@ static int nested_vmx_check_exception(struct kvm_vcpu *vcpu, unsigned long *exit
>> return 0;
>> }
>>
>> +static void vmx_clear_hlt(struct kvm_vcpu *vcpu)
>> +{
>> + /*
>> + * Ensure that we clear the HLT state in the VMCS. We don't need to
>> + * explicitly skip the instruction because if the HLT state is set,
>> + * then the instruction is already executing and RIP has already been
>> + * advanced.
>> + */
>> + if (kvm_hlt_in_guest(vcpu->kvm) &&
>> + vmcs_read32(GUEST_ACTIVITY_STATE) == GUEST_ACTIVITY_HLT)
>> + vmcs_write32(GUEST_ACTIVITY_STATE, GUEST_ACTIVITY_ACTIVE);
>> +}
>
> The clearing seems to be still missing around SMM -- I think you need to
> call vmx_clear_hlt() from pre_enter_smm().

Will do in v2.

Regards,
Wanpeng Li

\
 
 \ /
  Last update: 2018-03-09 01:53    [W:0.131 / U:5.384 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site