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Message-ID: <dc39988c-7b44-63b2-9ddf-6fa986fe7c3b@intel.com>
Date:   Fri, 18 Nov 2022 10:12:32 -0800
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Subject: Re: [PATCH v3 2/2] x86/pm: Add enumeration check before spec MSRs
 save/restore setup
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To:     Pawan Gupta <pawan.kumar.gupta@linux.intel.com>,
        Andrew Cooper <Andrew.Cooper3@citrix.com>,
        thomas.lendacky@amd.com, "H. Peter Anvin" <hpa@zytor.com>,
        hdegoede@redhat.com, Ingo Molnar <mingo@redhat.com>,
        "Rafael J. Wysocki" <rafael@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>, x86@kernel.org,
        Pavel Machek <pavel@ucw.cz>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        David.Kaplan@amd.com, Borislav Petkov <bp@alien8.de>
Cc:     linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org,
        Daniel Sneddon <daniel.sneddon@linux.intel.com>,
        antonio.gomez.iglesias@linux.intel.com
References: <cover.1668539735.git.pawan.kumar.gupta@linux.intel.com>
 <c24db75d69df6e66c0465e13676ad3f2837a2ed8.1668539735.git.pawan.kumar.gupta@linux.intel.com>
From:   Dave Hansen <dave.hansen@intel.com>
In-Reply-To: <c24db75d69df6e66c0465e13676ad3f2837a2ed8.1668539735.git.pawan.kumar.gupta@linux.intel.com>
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On 11/15/22 11:17, Pawan Gupta wrote:
> To fix this, add the corresponding X86_FEATURE bit for each MSR.  Avoid
> trying to manipulate the MSR when the feature bit is clear. This
> required adding a X86_FEATURE bit for MSRs that do not have one already,
> but it's a small price to pay.
> 
> Fixes: 73924ec4d560 ("x86/pm: Save the MSR validity status at context setup")
> Reported-by: Hans de Goede <hdegoede@redhat.com>
> Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
> Cc: stable@kernel.org

Thanks for fixing this up.  The X86_FEATURE approach is a good one.  The
"poking at random MSRs" always seemed a bit wonky.

Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>