From: Liran Alon <liran.alon@oracle.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Sean Christopherson" <sean.j.christopherson@intel.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>,
"Radim Krčmář" <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>
Subject: Re: [PATCH v4 11/19] x86/cpu: Print VMX flags in /proc/cpuinfo using VMX_FEATURES_*
Date: Thu, 12 Dec 2019 19:52:55 +0200 [thread overview]
Message-ID: <DA429131-7A4C-4B74-A020-6CE7622ED2F8@oracle.com> (raw)
In-Reply-To: <52dd758d-a590-52a6-4248-22d6852b75cd@redhat.com>
> On 12 Dec 2019, at 19:47, Paolo Bonzini <pbonzini@redhat.com> wrote:
>
> 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
>
True. But it relies on /dev/msr0 (exposed from msr kernel module) to be able to read any host arbitrary MSR.
It’s much more elegant to just report CPU VMX features in a /proc/cpuinfo pseudo-file and don’t require strong privileges.
Why should CPU VMX features be treated differently than standard CPUID deduced features?
CPU SVM features are also present in /proc/cpuinfo today (Because they are deduced from CPUID leafs). So it should be similar.
-Liran
next prev parent reply other threads:[~2019-12-12 17:55 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-28 1:39 [PATCH v4 00/19] x86/cpu: Clean up handling of VMX features Sean Christopherson
2019-11-28 1:39 ` [PATCH v4 01/19] x86/msr-index: Clean up bit defines for IA32_FEATURE_CONTROL MSR Sean Christopherson
2019-11-28 21:07 ` kbuild test robot
2019-11-28 21:07 ` kbuild test robot
2019-11-30 20:52 ` kbuild test robot
2019-11-30 20:52 ` kbuild test robot
2019-12-02 19:06 ` Sean Christopherson
2019-12-02 19:06 ` Sean Christopherson
2019-12-12 9:25 ` Borislav Petkov
2019-12-12 9:25 ` Borislav Petkov
2019-12-12 17:48 ` Sean Christopherson
2019-12-12 17:48 ` Sean Christopherson
2019-12-12 18:19 ` Borislav Petkov
2019-12-12 18:19 ` Borislav Petkov
2019-11-28 1:39 ` [PATCH v4 02/19] selftests: kvm: Replace manual MSR defs with common msr-index.h Sean Christopherson
2019-11-28 1:40 ` [PATCH v4 03/19] tools arch x86: Sync msr-index.h from kernel sources Sean Christopherson
2019-11-28 1:40 ` [PATCH v4 04/19] x86/intel: Initialize IA32_FEAT_CTL MSR at boot Sean Christopherson
2019-11-28 1:40 ` [PATCH v4 05/19] x86/mce: WARN once if IA32_FEAT_CTL MSR is left unlocked Sean Christopherson
2019-11-28 1:40 ` [PATCH v4 06/19] x86/centaur: Use common IA32_FEAT_CTL MSR initialization Sean Christopherson
2019-11-28 1:40 ` [PATCH v4 07/19] x86/zhaoxin: " Sean Christopherson
2019-11-28 1:40 ` [PATCH v4 08/19] x86/cpu: Clear VMX feature flag if VMX is not fully enabled Sean Christopherson
2019-11-28 1:40 ` [PATCH v4 09/19] x86/vmx: Introduce VMX_FEATURES_* Sean Christopherson
2019-11-28 1:40 ` [PATCH v4 10/19] x86/cpu: Detect VMX features on Intel, Centaur and Zhaoxin CPUs Sean Christopherson
2019-12-12 11:38 ` Borislav Petkov
2019-12-12 17:55 ` Sean Christopherson
2019-12-12 18:24 ` Borislav Petkov
2019-11-28 1:40 ` [PATCH v4 11/19] x86/cpu: Print VMX flags in /proc/cpuinfo using VMX_FEATURES_* Sean Christopherson
2019-12-12 12:26 ` Borislav Petkov
2019-12-12 14:13 ` Paolo Bonzini
2019-12-12 15:52 ` Liran Alon
2019-12-12 15:57 ` Paolo Bonzini
2019-12-12 17:43 ` Sean Christopherson
2019-12-12 17:47 ` Paolo Bonzini
2019-12-12 17:52 ` Liran Alon [this message]
2019-12-12 17:57 ` Jim Mattson
2019-12-12 18:04 ` Liran Alon
2019-12-12 18:27 ` Sean Christopherson
2019-12-12 18:32 ` Borislav Petkov
2019-12-12 17:47 ` Liran Alon
2019-12-12 18:18 ` Sean Christopherson
2019-12-12 18:23 ` Paolo Bonzini
2019-12-21 3:48 ` Sean Christopherson
2019-11-28 1:40 ` [PATCH v4 12/19] x86/cpu: Set synthetic VMX cpufeatures during init_ia32_feat_ctl() Sean Christopherson
2019-11-28 1:40 ` [PATCH v4 13/19] x86/cpufeatures: Add flag to track whether MSR IA32_FEAT_CTL is configured Sean Christopherson
2019-11-28 1:40 ` [PATCH v4 14/19] KVM: VMX: Drop initialization of IA32_FEAT_CTL MSR Sean Christopherson
2019-11-28 1:40 ` [PATCH v4 15/19] KVM: VMX: Use VMX feature flag to query BIOS enabling Sean Christopherson
2019-11-28 1:40 ` [PATCH v4 16/19] KVM: VMX: Check for full VMX support when verifying CPU compatibility Sean Christopherson
2019-11-28 1:40 ` [PATCH v4 17/19] KVM: VMX: Use VMX_FEATURE_* flags to define VMCS control bits Sean Christopherson
2019-11-28 1:40 ` [PATCH v4 18/19] perf/x86: Provide stubs of KVM helpers for non-Intel CPUs Sean Christopherson
2019-11-28 1:40 ` [PATCH v4 19/19] KVM: VMX: Allow KVM_INTEL when building for Centaur and/or Zhaoxin CPUs Sean Christopherson
2019-12-12 14:07 ` [PATCH v4 00/19] x86/cpu: Clean up handling of VMX features Borislav Petkov
2019-12-21 3:44 ` Sean Christopherson
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