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Subject: Re: [PATCH v4 11/19] x86/cpu: Print VMX flags in /proc/cpuinfo using
 VMX_FEATURES_*
To:     Sean Christopherson <sean.j.christopherson@intel.com>
Cc:     Liran Alon <liran.alon@oracle.com>, Borislav Petkov <bp@alien8.de>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, x86@kernel.org,
        "H. Peter Anvin" <hpa@zytor.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Jiri Olsa <jolsa@redhat.com>,
        Namhyung Kim <namhyung@kernel.org>,
        =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= <rkrcmar@redhat.com>,
        Vitaly Kuznetsov <vkuznets@redhat.com>,
        Wanpeng Li <wanpengli@tencent.com>,
        Jim Mattson <jmattson@google.com>,
        Joerg Roedel <joro@8bytes.org>,
        Tony Luck <tony.luck@intel.com>,
        Tony W Wang-oc <TonyWWang-oc@zhaoxin.com>,
        Len Brown <lenb@kernel.org>, Shuah Khan <shuah@kernel.org>,
        linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
        linux-edac@vger.kernel.org, linux-pm@vger.kernel.org,
        linux-kselftest@vger.kernel.org,
        Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
References: <20191128014016.4389-1-sean.j.christopherson@intel.com>
 <20191128014016.4389-12-sean.j.christopherson@intel.com>
 <20191212122646.GE4991@zn.tnic>
 <d0b21e7e-69f5-09f9-3e1c-14d49fa42b9f@redhat.com>
 <4A24DE75-4E68-4EC6-B3F3-4ACB0EE82BF0@oracle.com>
 <17c6569e-d0af-539c-6d63-f4c07367d8d1@redhat.com>
 <20191212174357.GE3163@linux.intel.com>
From:   Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <52dd758d-a590-52a6-4248-22d6852b75cd@redhat.com>
Date:   Thu, 12 Dec 2019 18:47:32 +0100
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On 12/12/19 18:43, Sean Christopherson wrote:
> Key word being "usually".  My intent in printing out partially redundant
> flags was to help users debug/understand why the combined feature isn't
> supported.  E.g. userspace can already easily (relatively speaking) query
> flexpriority support via /sys/module/kvm_intel/parameters/flexpriority.
> But if that comes back "N", the user has no way to determine exactly why
> flexpriority is disabled.

There are tools such as vmxcap.  It is part of QEMU, but I wouldn't mind
moving it into the kernel tree.

Paolo