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Date:   Wed, 9 Nov 2022 22:09:03 -0800
From:   Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
To:     Andrew Cooper <Andrew.Cooper3@citrix.com>
Cc:     Borislav Petkov <bp@alien8.de>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        "x86@kernel.org" <x86@kernel.org>,
        "H. Peter Anvin" <hpa@zytor.com>,
        "Rafael J. Wysocki" <rafael@kernel.org>,
        Pavel Machek <pavel@ucw.cz>,
        "hdegoede@redhat.com" <hdegoede@redhat.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-pm@vger.kernel.org" <linux-pm@vger.kernel.org>,
        Daniel Sneddon <daniel.sneddon@linux.intel.com>,
        "antonio.gomez.iglesias@linux.intel.com" 
        <antonio.gomez.iglesias@linux.intel.com>
Subject: Re: [PATCH 2/3] x86/cpu/amd: Add feature bit for MSR_AMD64_LS_CFG
 enumeration
Message-ID: <20221110060903.vud266getvlihxet@desk>
References: <cover.1663025154.git.pawan.kumar.gupta@linux.intel.com>
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On Thu, Nov 10, 2022 at 12:00:11AM +0000, Andrew Cooper wrote:
>On 09/11/2022 17:37, Pawan Gupta wrote:
>> If SSBD is the only reason to restore MSR_AMD64_LS_CFG then we should be
>> able to use X86_FEATURE_LS_CFG_SSBD for enumeration.
>
>Yeah, although it occurs to me that you probably don't want to
>save/restore the whole MSR.  It's full of other things which want to
>stay in their current configuration.

Upstream currently saves and restores the whole MSR_AMD64_LS_CFG at
suspend/resume.

Is it that the configuration saved at suspend(other than SSBD) will not
be relevant at resume for this MSR? Is there any harm if keep the
current behavior?