From: Tao Xu <tao3.xu@intel.com>
To: Sean Christopherson <sean.j.christopherson@intel.com>
Cc: pbonzini@redhat.com, rkrcmar@redhat.com, corbet@lwn.net,
tglx@linutronix.de, mingo@redhat.com, bp@alien8.de,
hpa@zytor.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
fenghua.yu@intel.com, xiaoyao.li@linux.intel.com,
jingqi.liu@intel.com
Subject: Re: [PATCH v7 3/3] KVM: vmx: handle vm-exit for UMWAIT and TPAUSE
Date: Sat, 13 Jul 2019 22:22:59 +0800 [thread overview]
Message-ID: <babf6abf-3e03-1e33-8dd9-ee847957be6f@intel.com> (raw)
In-Reply-To: <20190712160352.GD29659@linux.intel.com>
On 7/13/2019 12:03 AM, Sean Christopherson wrote:
> On Fri, Jul 12, 2019 at 04:29:07PM +0800, Tao Xu wrote:
>> --- a/arch/x86/kvm/vmx/nested.c
>> +++ b/arch/x86/kvm/vmx/nested.c
>> @@ -5213,6 +5213,9 @@ bool nested_vmx_exit_reflected(struct kvm_vcpu *vcpu, u32 exit_reason)
>> case EXIT_REASON_ENCLS:
>> /* SGX is never exposed to L1 */
>> return false;
>> + case EXIT_REASON_UMWAIT: case EXIT_REASON_TPAUSE:
>
> Grouped case statements are usually stacked vertically, e.g.:
>
> case EXIT_REASON_UMWAIT:
> case EXIT_REASON_TPAUSE:
>Ok, thank you for your suggestion.
>> + return nested_cpu_has2(vmcs12,
>> + SECONDARY_EXEC_ENABLE_USR_WAIT_PAUSE);
>> default:
>> return true;
>> }
>> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
>> index 0787f140d155..e026b1313dc3 100644
>> --- a/arch/x86/kvm/vmx/vmx.c
>> +++ b/arch/x86/kvm/vmx/vmx.c
>> @@ -5349,6 +5349,20 @@ static int handle_monitor(struct kvm_vcpu *vcpu)
>> return handle_nop(vcpu);
>> }
>>
>> +static int handle_umwait(struct kvm_vcpu *vcpu)
>> +{
>> + kvm_skip_emulated_instruction(vcpu);
>> + WARN(1, "this should never happen\n");
>
> Blech. I'm guessing this code was copy-pasted from handle_xsaves() and
> handle_xrstors(). The blurb of "this should never happen" isn't very
> helpful, e.g. the WARN itself makes it pretty obvious that we don't expect
> to reach this point. WARN_ONCE would also be preferable, no need to spam
> the log in the event things go completely haywire.
>
> Rather than propagate ugly code, what about defining a common helper, e.g.
>
> static int handle_unexpected_vmexit(struct kvm_vcpu *vcpu)
> {
> kvm_skip_emulated_instruction(vcpu);
> WARN_ONCE(1, "Unexpected VM-Exit = 0x%x", vmcs_read32(VM_EXIT_REASON));
> return 1;
> }
>
> ...
> {
> [EXIT_REASON_XSAVES] = handle_unexpected_vmexit,
> [EXIT_REASON_XRSTORS] = handle_unexpected_vmexit,
>
> [EXIT_REASON_UMWAIT] = handle_unexpected_vmexit,
> [EXIT_REASON_TPAUSE] = handle_unexpected_vmexit,
>
> }
>
Thank you Sean, I will do this in next version of patch.
>> + return 1;
>> +}
>> +
>> +static int handle_tpause(struct kvm_vcpu *vcpu)
>> +{
>> + kvm_skip_emulated_instruction(vcpu);
>> + WARN(1, "this should never happen\n");
>> + return 1;
>> +}
>> +
>> static int handle_invpcid(struct kvm_vcpu *vcpu)
>> {
>> u32 vmx_instruction_info;
>> @@ -5559,6 +5573,8 @@ static int (*kvm_vmx_exit_handlers[])(struct kvm_vcpu *vcpu) = {
>> [EXIT_REASON_VMFUNC] = handle_vmx_instruction,
>> [EXIT_REASON_PREEMPTION_TIMER] = handle_preemption_timer,
>> [EXIT_REASON_ENCLS] = handle_encls,
>> + [EXIT_REASON_UMWAIT] = handle_umwait,
>> + [EXIT_REASON_TPAUSE] = handle_tpause,
>> };
>>
>> static const int kvm_vmx_max_exit_handlers =
>> --
>> 2.20.1
>>
prev parent reply other threads:[~2019-07-13 14:23 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-12 8:29 [PATCH v7 0/3] KVM: x86: Enable user wait instructions Tao Xu
2019-07-12 8:29 ` [PATCH v7 1/3] KVM: x86: add support for " Tao Xu
2019-07-12 15:13 ` Sean Christopherson
2019-07-15 1:11 ` Tao Xu
2019-07-12 8:29 ` [PATCH v7 2/3] KVM: vmx: Emulate MSR IA32_UMWAIT_CONTROL Tao Xu
2019-07-12 15:52 ` Sean Christopherson
2019-07-15 1:22 ` Tao Xu
2019-07-15 14:16 ` Sean Christopherson
2019-07-16 16:03 ` Eduardo Habkost
2019-07-17 1:17 ` Tao Xu
2019-07-17 2:03 ` Tao Xu
2019-07-12 8:29 ` [PATCH v7 3/3] KVM: vmx: handle vm-exit for UMWAIT and TPAUSE Tao Xu
2019-07-12 16:03 ` Sean Christopherson
2019-07-13 14:22 ` Tao Xu [this message]
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