From: Wanpeng Li <kernellwp@gmail.com>
To: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: LKML <linux-kernel@vger.kernel.org>, kvm <kvm@vger.kernel.org>,
Paolo Bonzini <pbonzini@redhat.com>
Subject: Re: [PATCH 2/3] KVM: X86: Provides userspace with a capability to not intercept HLT
Date: Fri, 9 Mar 2018 08:51:44 +0800 [thread overview]
Message-ID: <CANRm+Cya+QLJV7wX3GzUbKRA+sSPMmDb4sVtk+W6bC70aN8f+Q@mail.gmail.com> (raw)
In-Reply-To: <20180308204029.GK12290@flask>
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
next prev parent reply other threads:[~2018-03-09 0:51 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-01 9:49 [PATCH 1/3] KVM: X86: Provides userspace with a capability to not intercept MWAIT Wanpeng Li
2018-03-01 9:49 ` [PATCH 2/3] KVM: X86: Provides userspace with a capability to not intercept HLT Wanpeng Li
2018-03-08 20:40 ` Radim Krčmář
2018-03-09 0:51 ` Wanpeng Li [this message]
2018-03-01 9:49 ` [PATCH 3/3] KVM: X86: Provides userspace with a capability to not intercept PAUSE Wanpeng Li
2018-03-08 20:52 ` Radim Krčmář
2018-03-08 20:31 ` [PATCH 1/3] KVM: X86: Provides userspace with a capability to not intercept MWAIT Radim Krčmář
2018-03-08 20:55 ` Radim Krčmář
2018-03-09 2:34 ` Wanpeng Li
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