From: Vitaly Kuznetsov <vkuznets@redhat.com>
To: Paolo Bonzini <pbonzini@redhat.com>,
Wanpeng Li <kernellwp@gmail.com>,
linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Cc: Sean Christopherson <sean.j.christopherson@intel.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.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 15:25:46 +0200 [thread overview]
Message-ID: <871rhq4ckl.fsf@vitty.brq.redhat.com> (raw)
In-Reply-To: <cfd9d16f-6ddf-60d5-f73d-bb49ccd4055f@redhat.com>
Paolo Bonzini <pbonzini@redhat.com> writes:
> 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.
>
> (But maybe this was discussed already; if so, please point me to the
> previous discussion).
>
Not for KVM_GET_SUPPORTED_CPUID but for KVM_GET_SUPPORTED_HV_CPUID: just
copying all the bits blindly is incorrect as e.g. SYNIC needs to be
enabled with KVM_CAP_HYPERV_SYNIC[2]. KVM PV features also have
pre-requisites, e.g. KVM_ASYNC_PF_DELIVERY_AS_INT requires an irqchip so
again copy/paste may not work.
--
Vitaly
next prev parent reply other threads:[~2020-10-22 13:25 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 [this message]
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
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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