Received-SPF: pass (google.com: domain of linux-kernel+bounces-146315-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:45d1:ec00::1 as permitted sender) client-ip=2604:1380:45d1:ec00::1;
Date: Mon, 15 Apr 2024 23:05:29 -0700
From: Dan Williams <dan.j.williams@intel.com>
To: Tom Lendacky <thomas.lendacky@amd.com>, Kuppuswamy Sathyanarayanan
	<sathyanarayanan.kuppuswamy@linux.intel.com>, <linux-kernel@vger.kernel.org>,
	<x86@kernel.org>, <linux-coco@lists.linux.dev>, <svsm-devel@coconut-svsm.dev>
CC: Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>,
	Borislav Petkov <bp@alien8.de>, Dave Hansen <dave.hansen@linux.intel.com>,
	"H. Peter Anvin" <hpa@zytor.com>, Andy Lutomirski <luto@kernel.org>, "Peter
 Zijlstra" <peterz@infradead.org>, Dan Williams <dan.j.williams@intel.com>,
	Michael Roth <michael.roth@amd.com>, Ashish Kalra <ashish.kalra@amd.com>,
	Joel Becker <jlbec@evilplan.org>, Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH v3 13/14] x86/sev: Hide SVSM attestation entries if not
 running under an SVSM
Message-ID: <661e15292be3_4d561294d6@dwillia2-mobl3.amr.corp.intel.com.notmuch>
References: <cover.1711405593.git.thomas.lendacky@amd.com>
 <67893f352bc54de61160bfe251cba0bdf0431f37.1711405593.git.thomas.lendacky@amd.com>
 <1f6f4477-0f2a-434a-8c89-3b5d51d61581@linux.intel.com>
 <19d69960-e548-a2e6-87d9-c463f2851613@amd.com>
 <e286883d-40ef-d749-26a8-7ec6fbd81eae@amd.com>
Content-Type: text/plain; charset="us-ascii"
Content-Disposition: inline
In-Reply-To: <e286883d-40ef-d749-26a8-7ec6fbd81eae@amd.com>
Precedence: bulk
MIME-Version: 1.0
X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?ruSPQLLPY1V1oo1sSFEjw45ot2Z+a7vFZlkVZuM30rdKJNFJetjn3Bxkvb8K?=
 =?us-ascii?Q?+xfr2rDyL7L7iWcakM0rGRQQsdh9ZMRSgP1TvbJ5Ho/oImvbmzM97+ohV5md?=
 =?us-ascii?Q?BPASrlOYBgtYhyY88gM8zLAJBn1fOSoKDNn4QJrY/j5BeiO56TAvRj05GWVc?=
 =?us-ascii?Q?y8wp9zMc87c2yFXtrAycABc05oj0KyACasOwt3HjHMXmzbUg4LP13FQbL0IU?=
 =?us-ascii?Q?YaSr4G9ONdURKcCLZJ9IYx73zj3ClHNvKwGf9GeC/iPgO+Hjg+BzCY4sMCit?=
 =?us-ascii?Q?rM51FMV42N9xXCbclLnhHIID/AZYmzpHGEvgI5yyBha47eRrSJfx5iy31t1b?=
 =?us-ascii?Q?ppM3kxM21MXKEvqSeOQ+fDRSegGaOqCjP+h4C368uAkxaJJVdXKulYzdkX/R?=
 =?us-ascii?Q?Eset9I57AMoGfe2MF1BoIMHv8aNWNUi6QPCouYpYRFd08DgJ6Y8w76Wb1H/Z?=
 =?us-ascii?Q?nIYcFIvH2t9m8lgDoW9XARaJsVSOUzRiVU7xpYtK8JzJvVabla/BCm5xj5yK?=
 =?us-ascii?Q?qGIbXW33OonjyBgGMeKIPPXwvek/gRoLL4xVXVBCWXybC8I+2FPoK8vVxdns?=
 =?us-ascii?Q?kfRZq0XgeA+1x2xGQYABjAek7+JUxA0hk140akvnkLpjP3dNd+4pe9V4SthF?=
 =?us-ascii?Q?8fCxmB9rIVDBQtAuRRM+JGLyKGJ8i1jLgQo8UiXj2jybOcCsG0cqkySAtE7Q?=
 =?us-ascii?Q?0Md/yNQQVtl9K7NWkvZ4pnJH9xoSllcVCXO2tdloRc1+T+fpXYs+PVbc3+pH?=
 =?us-ascii?Q?mHoPnjucFBt5ss0t0pA8reLgt9vJ2ahYtJu7EPTCptxsStVmvSHDZAe9sqUC?=
 =?us-ascii?Q?fpcLhimJBQHQfMhVPA5868pVez+gUNOtXLtDU7ipQHwUvur35OUAHSnPe8hu?=
 =?us-ascii?Q?TrF4apyKVhH76elv3+yvGmbLjJszcffKCF7tcUwhBYBXwXQ8w7xdwZOcbmmG?=
 =?us-ascii?Q?kN/3EdeyN9RziSHPctT1aJCEsaL3hyyrozwuojTwLnPQRnlMvYSZnogJGnaI?=
 =?us-ascii?Q?hK7kOzcOf8QlN0unIChao5XRBeNXRobUPD5HRZ1xoHEIaE853FPTM6tO8RkG?=
 =?us-ascii?Q?a5NGerPkHdG3Ez4i/TUj/nycoI9VwWBeeauoaMJmcNeKEOC19/NEi7LWo9hR?=
 =?us-ascii?Q?3KN0hKPxmJ15bUGQu6b3OhqzrshNED1rNzsunfaYM6A4ua2NINSrflPIN2ml?=
 =?us-ascii?Q?aJEw6Z3RoXZD57zwuUOIM3W0eHLAKw+ll8bM1A0GaZQAgA9Qc23LG1DNoukJ?=
 =?us-ascii?Q?DqgfxyW6XXQJlq4Zl+78jyADVefGss/GiWqDF6mn42k6D30hCBUIzwtmgDhT?=
 =?us-ascii?Q?VXsbUczukQ28pTb7Rd3B/f/YOpvyVsrYJbkZ4qMvKx+HnVsU0yKo5RTboiyk?=
 =?us-ascii?Q?0LtXyXqF1r/UUUqXBe3KnvxNI93d51kAWt/Lrs9jcMDIpJyBkxNSY7Hqmg3v?=
 =?us-ascii?Q?lDLakC1BorlEMtX/ype1BQuy/2Q3wn0Qa9F0ibPqoJ9BVdJLuxubteRTdZ0N?=
 =?us-ascii?Q?8cho0d88S99Sy7JZLPhxvN6aMZPcAAGdxzOdw+Xo2CYMHQ0xUUP+sZ9zNbWH?=
 =?us-ascii?Q?g8FT1k5hFORtOww2dsoV8KHUMprrdO0Xshhz5WfOJDbGDEdlh9QLl9+6TZAw?=
 =?us-ascii?Q?gg=3D=3D?=
X-MS-Exchange-CrossTenant-Network-Message-Id: c45fab62-0804-4954-e1f1-08dc5ddb3938
X-MS-Exchange-CrossTenant-AuthSource: PH8PR11MB8107.namprd11.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 16 Apr 2024 06:05:32.0419
 (UTC)
X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted
X-MS-Exchange-CrossTenant-Id: 46c98d88-e344-4ed4-8496-4ed7712e255d
X-MS-Exchange-CrossTenant-MailboxType: HOSTED
X-MS-Exchange-CrossTenant-UserPrincipalName: knAF3hXh1FRfFpRxZffRerOcsJy2xJvbEg1aOcik4OcNgmlr16j2G6boL+5HjtDs5pQrfF175eaCUlCwwXYC8i7wY9wW1gkoCmHG9K6RcaM=
X-MS-Exchange-Transport-CrossTenantHeadersStamped: SJ2PR11MB8471
X-OriginatorOrg: intel.com

Tom Lendacky wrote:
> On 4/12/24 10:52, Tom Lendacky wrote:
> > On 4/9/24 13:12, Kuppuswamy Sathyanarayanan wrote:
> >> On 3/25/24 3:26 PM, Tom Lendacky wrote:
> >>> Config-fs provides support to hide individual attribute entries. Using
> >>> this support, base the display of the SVSM related entries on the 
> >>> presence
> >>> of an SVSM.
> >>>
> >>> Cc: Joel Becker <jlbec@evilplan.org>
> >>> Cc: Christoph Hellwig <hch@lst.de>
> >>> Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
> >>> ---
> >>>   arch/x86/coco/core.c        |  4 ++++
> >>>   drivers/virt/coco/tsm.c     | 14 ++++++++++----
> >>>   include/linux/cc_platform.h |  8 ++++++++
> >>>   3 files changed, 22 insertions(+), 4 deletions(-)
> >>>
> 
> >>
> >> Any comment about the following query? I think introducing a CC flag 
> >> for this use
> >> case is over kill.
> >>
> >> https://lore.kernel.org/lkml/6b90b223-46e0-4e6d-a17c-5caf72e3c949@linux.intel.com/
> > 
> > If you don't think TDX will be able to make use of the SVSM attribute I 
> > can look at adding a callback. But I was waiting to see if anyone else 
> > had comments, for or against, before re-doing it all.
> > 
> 
> What about something like this (applied on top of patch 13):
> 
> diff --git a/arch/x86/coco/core.c b/arch/x86/coco/core.c
> index efa0f648f754..d07be9d05cd0 100644
> --- a/arch/x86/coco/core.c
> +++ b/arch/x86/coco/core.c
> @@ -12,7 +12,6 @@
>   
>   #include <asm/coco.h>
>   #include <asm/processor.h>
> -#include <asm/sev.h>
>   
>   enum cc_vendor cc_vendor __ro_after_init = CC_VENDOR_NONE;
>   u64 cc_mask __ro_after_init;
> @@ -79,9 +78,6 @@ static bool noinstr amd_cc_platform_has(enum cc_attr attr)
>   	case CC_ATTR_GUEST_STATE_ENCRYPT:
>   		return sev_status & MSR_AMD64_SEV_ES_ENABLED;
>   
> -	case CC_ATTR_GUEST_SVSM_PRESENT:
> -		return snp_get_vmpl();
> -
>   	/*
>   	 * With SEV, the rep string I/O instructions need to be unrolled
>   	 * but SEV-ES supports them through the #VC handler.
> diff --git a/drivers/virt/coco/sev-guest/sev-guest.c b/drivers/virt/coco/sev-guest/sev-guest.c
> index 0d2c9926a97c..68c881a50026 100644
> --- a/drivers/virt/coco/sev-guest/sev-guest.c
> +++ b/drivers/virt/coco/sev-guest/sev-guest.c
> @@ -1036,6 +1036,17 @@ static int sev_report_new(struct tsm_report *report, void *data)
>   	return 0;
>   }
>   
> +static bool sev_tsm_visibility(enum tsm_type type)
> +{
> +	/* Check for SVSM-related attributes */
> +	switch (type) {
> +	case TSM_TYPE_SERVICE_PROVIDER:
> +		return snp_get_vmpl();
> +	default:
> +		return false;
> +	}
> +}
> +
>   static struct tsm_ops sev_tsm_ops = {
>   	.name = KBUILD_MODNAME,
>   	.report_new = sev_report_new,
> @@ -1126,7 +1137,8 @@ static int __init sev_guest_probe(struct platform_device *pdev)
>   	/* Set the privlevel_floor attribute based on the current VMPL */
>   	sev_tsm_ops.privlevel_floor = snp_get_vmpl();
>   
> -	ret = tsm_register(&sev_tsm_ops, snp_dev, &tsm_report_extra_type);
> +	ret = tsm_register(&sev_tsm_ops, snp_dev, &tsm_report_extra_type,
> +			   sev_tsm_visibility);

I would have expected this in tsm_ops, but yes I think a callback lets
this fixup the ugly "extra" attributes situation as well.