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From: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
To: Sean Christopherson <sean.j.christopherson@intel.com>
Cc: "Thomas Gleixner" <tglx@linutronix.de>,
	"Ingo Molnar" <mingo@redhat.com>,
	"Borislav Petkov" <bp@alien8.de>,
	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>,
	"Paolo Bonzini" <pbonzini@redhat.com>,
	"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>,
	"Shuah Khan" <shuah@kernel.org>,
	linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
	linux-edac@vger.kernel.org, linux-kselftest@vger.kernel.org,
	"Borislav Petkov" <bp@suse.de>
Subject: Re: [PATCH v3 05/19] x86/mce: WARN once if IA32_FEATURE_CONTROL MSR is left unlocked
Date: Thu, 21 Nov 2019 12:45:38 +0200
Message-ID: <20191121104538.GD20907@linux.intel.com> (raw)
In-Reply-To: <20191119031240.7779-6-sean.j.christopherson@intel.com>

On Mon, Nov 18, 2019 at 07:12:26PM -0800, Sean Christopherson wrote:
> WARN if the IA32_FEATURE_CONTROL MSR is somehow left unlocked now that
> CPU initialization unconditionally locks the MSR.
> 
> Reviewed-by: Borislav Petkov <bp@suse.de>
> Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
> ---
>  arch/x86/kernel/cpu/mce/intel.c | 7 +++----
>  1 file changed, 3 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/x86/kernel/cpu/mce/intel.c b/arch/x86/kernel/cpu/mce/intel.c
> index 3e5b29acd301..5abc55a67fce 100644
> --- a/arch/x86/kernel/cpu/mce/intel.c
> +++ b/arch/x86/kernel/cpu/mce/intel.c
> @@ -119,11 +119,10 @@ static bool lmce_supported(void)
>  	 * generate a #GP fault.
>  	 */
>  	rdmsrl(MSR_IA32_FEATURE_CONTROL, tmp);
> -	if ((tmp & (FEAT_CTL_LOCKED | FEAT_CTL_LMCE_ENABLED)) ==
> -		   (FEAT_CTL_LOCKED | FEAT_CTL_LMCE_ENABLED))
> -		return true;

I'd add a prepending comment:

/*
 * FEAT_CTL_LOCKED should have been always set either by
 * BIOS before handover to the kernel or init_feature_control_msr().
 */

> +	if (WARN_ON_ONCE(!(tmp & FEAT_CTL_LOCKED)))
> +		return false;
>  
> -	return false;
> +	return tmp & FEAT_CTL_LMCE_ENABLED;
>  }
>  
>  bool mce_intel_cmci_poll(void)
> -- 
> 2.24.0
> 

/Jarkko

  reply index

Thread overview: 39+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-19  3:12 [PATCH v3 00/19] x86/cpu: Clean up handling of VMX features Sean Christopherson
2019-11-19  3:12 ` [PATCH v3 01/19] x86/msr-index: Clean up bit defines for IA32_FEATURE_CONTROL MSR Sean Christopherson
2019-11-19 11:15   ` Borislav Petkov
2019-11-19 23:18     ` Sean Christopherson
2019-11-20 17:48       ` Borislav Petkov
2019-11-21  9:46   ` Jarkko Sakkinen
2019-11-21 22:14     ` Sean Christopherson
2019-11-29 21:06       ` Jarkko Sakkinen
2019-11-29 21:11         ` Jarkko Sakkinen
2019-11-19  3:12 ` [PATCH v3 02/19] selftests: kvm: Replace manual MSR defs with common msr-index.h Sean Christopherson
2019-11-19  3:12 ` [PATCH v3 03/19] tools arch x86: Sync msr-index.h from kernel sources Sean Christopherson
2019-11-19  3:12 ` [PATCH v3 04/19] x86/intel: Initialize IA32_FEATURE_CONTROL MSR at boot Sean Christopherson
2019-11-19  4:41   ` Kai Huang
2019-11-19  5:03     ` Sean Christopherson
2019-11-21 10:39   ` Jarkko Sakkinen
2019-11-21 10:41     ` Jarkko Sakkinen
2019-11-21 11:05       ` Borislav Petkov
2019-11-21 22:12         ` Sean Christopherson
2019-11-22 12:34           ` Borislav Petkov
2019-11-19  3:12 ` [PATCH v3 05/19] x86/mce: WARN once if IA32_FEATURE_CONTROL MSR is left unlocked Sean Christopherson
2019-11-21 10:45   ` Jarkko Sakkinen [this message]
2019-11-19  3:12 ` [PATCH v3 06/19] x86/centaur: Use common IA32_FEATURE_CONTROL MSR initialization Sean Christopherson
2019-11-19  3:12 ` [PATCH v3 07/19] x86/zhaoxin: " Sean Christopherson
2019-11-19  3:12 ` [PATCH v3 08/19] KVM: VMX: Drop initialization of IA32_FEATURE_CONTROL MSR Sean Christopherson
2019-11-19  3:12 ` [PATCH v3 09/19] x86/cpu: Clear VMX feature flag if VMX is not fully enabled Sean Christopherson
2019-11-19  3:12 ` [PATCH v3 10/19] KVM: VMX: Use VMX feature flag to query BIOS enabling Sean Christopherson
2019-11-19  3:12 ` [PATCH v3 11/19] KVM: VMX: Check for full VMX support when verifying CPU compatibility Sean Christopherson
2019-11-19  3:12 ` [PATCH v3 12/19] x86/vmx: Introduce VMX_FEATURES_* Sean Christopherson
2019-11-21 16:52   ` Borislav Petkov
2019-11-21 21:50     ` Sean Christopherson
2019-11-22 18:36       ` Borislav Petkov
2019-11-22 19:09         ` Sean Christopherson
2019-11-19  3:12 ` [PATCH v3 13/19] x86/cpu: Detect VMX features on Intel, Centaur and Zhaoxin CPUs Sean Christopherson
2019-11-19  3:12 ` [PATCH v3 14/19] x86/cpu: Print VMX flags in /proc/cpuinfo using VMX_FEATURES_* Sean Christopherson
2019-11-19  3:12 ` [PATCH v3 15/19] x86/cpufeatures: Drop synthetic VMX feature flags Sean Christopherson
2019-11-19  3:12 ` [PATCH v3 16/19] KVM: VMX: Use VMX_FEATURE_* flags to define VMCS control bits Sean Christopherson
2019-11-19  3:12 ` [PATCH v3 17/19] x86/cpufeatures: Clean up synthetic virtualization flags Sean Christopherson
2019-11-19  3:12 ` [PATCH v3 18/19] perf/x86: Provide stubs of KVM helpers for non-Intel CPUs Sean Christopherson
2019-11-19  3:12 ` [PATCH v3 19/19] KVM: VMX: Allow KVM_INTEL when building for Centaur and/or Zhaoxin CPUs Sean Christopherson

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