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From: "Daniel P. Berrangé" <berrange@redhat.com>
To: "Huang, Kai" <kai.huang@intel.com>
Cc: "Williams, Dan J" <dan.j.williams@intel.com>,
	"James.Bottomley@HansenPartnership.com"
	<James.Bottomley@hansenpartnership.com>,
	"dhowells@redhat.com" <dhowells@redhat.com>,
	"sameo@rivosinc.com" <sameo@rivosinc.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"jarkko@kernel.org" <jarkko@kernel.org>,
	"bp@alien8.de" <bp@alien8.de>,
	"gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
	"peterz@infradead.org" <peterz@infradead.org>,
	"akpm@linux-foundation.org" <akpm@linux-foundation.org>,
	"sathyanarayanan.kuppuswamy@linux.intel.com"
	<sathyanarayanan.kuppuswamy@linux.intel.com>,
	"thomas.lendacky@amd.com" <thomas.lendacky@amd.com>,
	"dionnaglaze@google.com" <dionnaglaze@google.com>,
	"keyrings@vger.kernel.org" <keyrings@vger.kernel.org>,
	"brijesh.singh@amd.com" <brijesh.singh@amd.com>,
	"linux-coco@lists.linux.dev" <linux-coco@lists.linux.dev>,
	"x86@kernel.org" <x86@kernel.org>
Subject: Re: [PATCH 0/4] keys: Introduce a keys frontend for attestation reports
Date: Fri, 4 Aug 2023 17:19:30 +0100	[thread overview]
Message-ID: <ZM0lEvYJ+5IgybLT@redhat.com> (raw)
In-Reply-To: <6dec442c64faf2fecd21bcc77e4a6350e88948b9.camel@intel.com>

On Tue, Aug 01, 2023 at 11:45:12AM +0000, Huang, Kai wrote:
> The IOCTL vs /sysfs isn't discussed.
> 
> For instance, after rough thinking, why is the IOCTL better than below approach
> using /sysfs?
> 
> echo <REPORTDATA> > /sys/kernel/coco/tdx/attest/reportdata
> cat /sys/kernel/coco/tdx/attest/tdreport
> 
> Each "echo <REPORTDATA>" to '/sys/.../reportdata' triggers the driver to call
> TDCALL to get the TDREPORT, which is available at '/sys/.../tdreport'.

What would you suggest as behaviour with multiple processes writing
into 'reportdata' and trying to read from 'tdreport' in parallel ?
Splitting input and output across separate files removes any
transactional relationship between input and output. This approach
feels like it could easily result in buggy behaviour from concurrent
application usage, which would not be an issue with ioctl()

Also note, there needs to be scope for more than 1 input and 1 output
data items. For SNP guests, the VMPL is a input, and if fetching a
VMPL 0 report from under SVSM [1], an optional service GUID is needed.
With SVSM, there are three distinct output data blobs - attestation
report, services manifest and certificate data.

With regards,
Daniel

[1] https://www.amd.com/system/files/TechDocs/58019_1.00.pdf
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  parent reply	other threads:[~2023-08-04 16:19 UTC|newest]

Thread overview: 67+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-07-28 19:30 [PATCH 0/4] keys: Introduce a keys frontend for attestation reports Dan Williams
2023-07-28 19:30 ` [PATCH 1/4] keys: Introduce tsm keys Dan Williams
2023-07-28 19:40   ` Jarkko Sakkinen
2023-07-31 16:33   ` Peter Gonda
2023-07-31 17:48     ` Dan Williams
2023-07-31 18:14       ` Peter Gonda
2023-07-31 18:41         ` Dan Williams
2023-07-31 19:09           ` Dionna Amalie Glaze
2023-07-31 20:10             ` Dan Williams
2023-08-04 16:34           ` Peter Gonda
2023-08-04 22:24             ` Dan Williams
2023-08-05  5:11             ` Dan Williams
2023-08-01 18:01     ` Jarkko Sakkinen
2023-08-04  2:40       ` Dan Williams
2023-08-04 16:37         ` Dionna Amalie Glaze
2023-08-04 16:46           ` James Bottomley
2023-08-04 17:07             ` Dionna Amalie Glaze
2023-08-04 17:12               ` James Bottomley
2023-07-28 19:31 ` [PATCH 2/4] virt: sevguest: Prep for kernel internal {get, get_ext}_report() Dan Williams
2023-07-28 19:31 ` [PATCH 3/4] mm/slab: Add __free() support for kvfree Dan Williams
2023-07-28 19:31 ` [PATCH 4/4] virt: sevguest: Add TSM key support for SNP_{GET, GET_EXT}_REPORT Dan Williams
2023-07-31 16:45   ` Peter Gonda
2023-07-31 18:05     ` Dan Williams
2023-07-31 18:28       ` Peter Gonda
2023-07-28 19:34 ` [PATCH 0/4] keys: Introduce a keys frontend for attestation reports Jarkko Sakkinen
2023-07-28 19:44   ` Dan Williams
2023-07-31 10:09     ` Jarkko Sakkinen
2023-07-31 17:33       ` Dan Williams
2023-07-31 22:41       ` Huang, Kai
2023-08-01 18:48         ` Jarkko Sakkinen
2023-07-29 18:17 ` James Bottomley
2023-07-30  4:56   ` Dan Williams
2023-07-30 12:59     ` James Bottomley
2023-07-31 17:24       ` Dan Williams
2023-08-01 11:45       ` Huang, Kai
2023-08-01 12:03         ` James Bottomley
2023-08-01 12:30           ` James Bottomley
2023-08-02  0:10             ` Huang, Kai
2023-08-02 12:41               ` James Bottomley
2023-08-02 23:13                 ` Huang, Kai
2023-08-04  3:53           ` Dan Williams
2023-08-04  2:22         ` Dan Williams
2023-08-04 16:19         ` Daniel P. Berrangé [this message]
2023-08-04 21:49           ` Huang, Kai
2023-08-05 11:05           ` James Bottomley
2023-08-05  2:37       ` Dan Williams
2023-08-05 13:30         ` James Bottomley
2023-08-07 23:33           ` Dan Williams
2023-08-08 14:19             ` James Bottomley
2023-08-08 14:53               ` Peter Gonda
2023-08-08 14:54               ` Sathyanarayanan Kuppuswamy
2023-08-08 15:48                 ` Dan Williams
2023-08-08 16:07                   ` Dionna Amalie Glaze
2023-08-08 16:43                     ` Dan Williams
2023-08-08 17:21                       ` Dionna Amalie Glaze
2023-08-08 18:17                         ` Dan Williams
2023-08-08 23:32                           ` Huang, Kai
2023-08-09  3:27                             ` Dan Williams
2023-08-09 16:14                               ` Peter Gonda
2023-08-08 18:16                     ` James Bottomley
2023-08-08 18:48                       ` Dionna Amalie Glaze
2023-08-08 19:37                         ` James Bottomley
2023-08-08 20:04                           ` Dionna Amalie Glaze
2023-08-08 21:46                             ` James Bottomley
2023-08-08 22:33                               ` Dionna Amalie Glaze
2023-08-08 15:14               ` Dan Williams
2023-08-10 14:50             ` Jarkko Sakkinen

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