From: Paolo Bonzini <pbonzini@redhat.com>
To: Jim Mattson <jmattson@google.com>
Cc: Wanpeng Li <kernellwp@gmail.com>,
LKML <linux-kernel@vger.kernel.org>,
kvm list <kvm@vger.kernel.org>,
Sean Christopherson <sean.j.christopherson@intel.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Joerg Roedel <joro@8bytes.org>
Subject: Re: [PATCH] KVM: X86: Expose KVM_HINTS_REALTIME in KVM_GET_SUPPORTED_CPUID
Date: Thu, 22 Oct 2020 18:37:45 +0200 [thread overview]
Message-ID: <281bca2d-d534-1032-eed3-7ee7705cb12c@redhat.com> (raw)
In-Reply-To: <CALMp9eR3Ng-WBrumXaJAecLWZECf-1NfzW+eTA0VxWuAcKAjAA@mail.gmail.com>
On 22/10/20 18:35, Jim Mattson wrote:
> On Thu, Oct 22, 2020 at 6:02 AM Paolo Bonzini <pbonzini@redhat.com> wrote:
>>
>> On 22/10/20 03:34, Wanpeng Li wrote:
>>> From: Wanpeng Li <wanpengli@tencent.com>
>>>
>>> Per KVM_GET_SUPPORTED_CPUID ioctl documentation:
>>>
>>> This ioctl returns x86 cpuid features which are supported by both the
>>> hardware and kvm in its default configuration.
>>>
>>> A well-behaved userspace should not set the bit if it is not supported.
>>>
>>> Suggested-by: Jim Mattson <jmattson@google.com>
>>> Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
>>
>> It's common for userspace to copy all supported CPUID bits to
>> KVM_SET_CPUID2, I don't think this is the right behavior for
>> KVM_HINTS_REALTIME.
>
> That is not how the API is defined, but I'm sure you know that. :-)
Yes, though in my defense :) KVM_HINTS_REALTIME is not a property of the
kernel, it's a property of the environment that the guest runs in. This
was the original reason to separate it from other feature bits in the
same leaf.
Paolo
next prev parent reply other threads:[~2020-10-22 16:37 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-22 1:34 [PATCH] KVM: X86: Expose KVM_HINTS_REALTIME in KVM_GET_SUPPORTED_CPUID Wanpeng Li
2020-10-22 13:02 ` Paolo Bonzini
2020-10-22 13:25 ` Vitaly Kuznetsov
2020-10-22 13:31 ` Xiaoyao Li
2020-10-22 14:06 ` Paolo Bonzini
2020-10-22 14:28 ` Xiaoyao Li
2020-10-22 14:44 ` Paolo Bonzini
2020-10-22 16:35 ` Jim Mattson
2020-10-22 16:37 ` Paolo Bonzini [this message]
2020-10-22 17:13 ` Jim Mattson
2020-10-23 9:07 ` Paolo Bonzini
2020-10-23 17:03 ` Jim Mattson
2020-10-23 0:27 ` Wanpeng Li
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