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From: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
To: Borislav Petkov <bp@alien8.de>
Cc: Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
	"Rafael J. Wysocki" <rafael@kernel.org>,
	Pavel Machek <pavel@ucw.cz>,
	Andrew Cooper <Andrew.Cooper3@citrix.com>,
	hdegoede@redhat.com, linux-kernel@vger.kernel.org,
	linux-pm@vger.kernel.org,
	Daniel Sneddon <daniel.sneddon@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
Date: Tue, 8 Nov 2022 18:18:29 -0800	[thread overview]
Message-ID: <20221109021829.h26g4puxxfrv7xxg@desk> (raw)
In-Reply-To: <Y2rh6FN+gbD6Vbzj@zn.tnic>

On Wed, Nov 09, 2022 at 12:10:32AM +0100, Borislav Petkov wrote:
>On Tue, Nov 08, 2022 at 02:51:41PM -0800, Pawan Gupta wrote:
>> Looking at bsp_init_amd() this feature bit will only be set on AMD
>> families 0x15-0x17. Andrew mentioned that the MSR LS_CFG is present on
>> AMD family >= 0x10 && family <= 0x18.
>
>Do you need to save that MSR on those families?
>
>Or do 0x15-0x18 suffice?
>
>Yes, 0x18 because that's Hygon and that does its own detection.
>
>So, do you need to save it on families 0x10-0x14?

As per Andrew's comment [1] the MSR needs to be restored for dispatch
serialising bit(except for family 0x11) :

   AMD LS_CFG is more complicated, because the dispatch serialising bit
   needs setting unilaterally (families 0x10, 0x12 thru 0x18), but the SSBD
   control ought to resolve on the next context switch.

[1] https://lore.kernel.org/lkml/6049e5bc-122f-5b4c-c1dc-0591eccf3525@citrix.com/

  parent reply	other threads:[~2022-11-09  2:20 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-09-12 23:38 [PATCH 0/3] Check enumeration before MSR save/restore Pawan Gupta
2022-09-12 23:39 ` [PATCH 1/3] x86/tsx: Add feature bit for TSX control MSR support Pawan Gupta
2022-11-08 18:27   ` Dave Hansen
2022-11-08 22:06     ` Pawan Gupta
2022-09-12 23:40 ` [PATCH 2/3] x86/cpu/amd: Add feature bit for MSR_AMD64_LS_CFG enumeration Pawan Gupta
2022-11-08 18:54   ` Borislav Petkov
2022-11-08 22:51     ` Pawan Gupta
2022-11-08 23:10       ` Borislav Petkov
2022-11-09  0:45         ` Andrew Cooper
2022-11-09 17:37           ` Pawan Gupta
2022-11-09 18:34             ` Borislav Petkov
2022-11-09 21:41               ` Pawan Gupta
2022-11-10  0:00             ` Andrew Cooper
2022-11-10  6:09               ` Pawan Gupta
2022-11-09  2:18         ` Pawan Gupta [this message]
2022-09-12 23:41 ` [PATCH 3/3] x86/pm: Add enumeration check before spec MSRs save/restore setup Pawan Gupta
2022-11-08 18:40   ` Dave Hansen
2022-11-08 22:09     ` Pawan Gupta
2022-09-13  0:50 ` [PATCH 0/3] Check enumeration before MSR save/restore Pawan Gupta
2022-09-17 11:42   ` Hans de Goede
2022-09-19 16:56     ` Pawan Gupta
2022-11-08 18:16 ` Hans de Goede
2022-11-08 18:26   ` Borislav Petkov
2022-11-08 18:55     ` Borislav Petkov
2022-11-08 22:07       ` Pawan Gupta

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