linux-kernel - [PATCH v3 05/19] x86/mce: WARN once if IA32_FEATURE

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Message-Id: <20191119031240.7779-6-sean.j.christopherson@intel.com>
Date:   Mon, 18 Nov 2019 19:12:26 -0800
From:   Sean Christopherson <sean.j.christopherson@...el.com>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        x86@...nel.org
Cc:     "H. Peter Anvin" <hpa@...or.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>,
        Tony Luck <tony.luck@...el.com>,
        Tony W Wang-oc <TonyWWang-oc@...oxin.com>,
        Shuah Khan <shuah@...nel.org>, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org, linux-edac@...r.kernel.org,
        linux-kselftest@...r.kernel.org, Borislav Petkov <bp@...e.de>,
        Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
Subject: [PATCH v3 05/19] x86/mce: WARN once if IA32_FEATURE_CONTROL MSR is left unlocked

WARN if the IA32_FEATURE_CONTROL MSR is somehow left unlocked now that
CPU initialization unconditionally locks the MSR.

Reviewed-by: Borislav Petkov <bp@...e.de>
Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.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;
+	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