From: Paolo Bonzini <pbonzini@redhat.com>
To: Tao Xu <tao3.xu@intel.com>,
rkrcmar@redhat.com, corbet@lwn.net, tglx@linutronix.de,
mingo@redhat.com, bp@alien8.de, hpa@zytor.com,
sean.j.christopherson@intel.com
Cc: x86@kernel.org, kvm@vger.kernel.org, linux-doc@vger.kernel.org,
linux-kernel@vger.kernel.org, jingqi.liu@intel.com
Subject: Re: [PATCH v2 1/3] KVM: x86: add support for user wait instructions
Date: Wed, 29 May 2019 03:24:14 +0200 [thread overview]
Message-ID: <419f62f3-69a8-7ec0-5eeb-20bed69925f2@redhat.com> (raw)
In-Reply-To: <20190524075637.29496-2-tao3.xu@intel.com>
On 24/05/19 09:56, Tao Xu wrote:
> +7.19 KVM_CAP_ENABLE_USR_WAIT_PAUSE
> +
> +Architectures: x86
> +Parameters: args[0] whether feature should be enabled or not
> +
> +With this capability enabled, a VM can use UMONITOR, UMWAIT and TPAUSE
> +instructions. If the instruction causes a delay, the amount of
> +time delayed is called here the physical delay. The physical delay is
> +first computed by determining the virtual delay (the time to delay
> +relative to the VM’s timestamp counter). Otherwise, UMONITOR, UMWAIT
> +and TPAUSE cause an invalid-opcode exception(#UD).
> +
There is no need to make it a capability. You can just check the guest
CPUID and see if it includes X86_FEATURE_WAITPKG.
Paolo
next prev parent reply other threads:[~2019-05-29 1:24 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-24 7:56 [PATCH v2 0/3] KVM: x86: Enable user wait instructions Tao Xu
2019-05-24 7:56 ` [PATCH v2 1/3] KVM: x86: add support for " Tao Xu
2019-05-27 10:30 ` Peter Zijlstra
2019-05-28 5:11 ` Tao Xu
2019-05-28 6:11 ` Wanpeng Li
2019-05-28 7:19 ` Tao Xu
2019-05-29 1:26 ` Paolo Bonzini
2019-05-29 1:25 ` Paolo Bonzini
2019-05-29 1:24 ` Paolo Bonzini [this message]
2019-05-29 2:05 ` Tao Xu
2019-05-29 2:38 ` Paolo Bonzini
2019-05-29 3:12 ` Tao Xu
2019-05-24 7:56 ` [PATCH v2 2/3] KVM: vmx: Emulate MSR IA32_UMWAIT_CONTROL Tao Xu
2019-05-29 1:29 ` Paolo Bonzini
2019-05-29 1:38 ` Tao Xu
2019-05-24 7:56 ` [PATCH v2 3/3] KVM: vmx: handle vm-exit for UMWAIT and TPAUSE Tao Xu
2019-05-29 1:28 ` Paolo Bonzini
2019-05-29 2:25 ` Tao Xu
2019-05-29 2:39 ` Paolo Bonzini
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