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Subject: Re: [PATCH] KVM: X86: Expose KVM_HINTS_REALTIME in
 KVM_GET_SUPPORTED_CPUID
To:     Wanpeng Li <kernellwp@gmail.com>, linux-kernel@vger.kernel.org,
        kvm@vger.kernel.org
Cc:     Sean Christopherson <sean.j.christopherson@intel.com>,
        Vitaly Kuznetsov <vkuznets@redhat.com>,
        Wanpeng Li <wanpengli@tencent.com>,
        Jim Mattson <jmattson@google.com>,
        Joerg Roedel <joro@8bytes.org>
References: <1603330475-7063-1-git-send-email-wanpengli@tencent.com>
From:   Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <cfd9d16f-6ddf-60d5-f73d-bb49ccd4055f@redhat.com>
Date:   Thu, 22 Oct 2020 15:02:17 +0200
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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).

Paolo