linux-kernel - Re: [PATCH v4 3/4] tpm: add SNP SVSM vTPM driver

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Message-ID: <setj52yumlcd43q5hnsfntig5mv7uxhh6n32puahkmwg75wtlc@ft3xk3vybpwn>
Date: Thu, 27 Mar 2025 15:10:58 +0100
From: Stefano Garzarella <sgarzare@...hat.com>
To: Jarkko Sakkinen <jarkko@...nel.org>
Cc: Joerg Roedel <jroedel@...e.de>, Ingo Molnar <mingo@...hat.com>, 
	Dave Hansen <dave.hansen@...ux.intel.com>, Peter Huewe <peterhuewe@....de>, 
	Tom Lendacky <thomas.lendacky@....com>, Thomas Gleixner <tglx@...utronix.de>, x86@...nel.org, 
	James Bottomley <James.Bottomley@...senpartnership.com>, linux-kernel@...r.kernel.org, Borislav Petkov <bp@...en8.de>, 
	Jason Gunthorpe <jgg@...pe.ca>, "H. Peter Anvin" <hpa@...or.com>, linux-coco@...ts.linux.dev, 
	Claudio Carvalho <cclaudio@...ux.ibm.com>, Dov Murik <dovmurik@...ux.ibm.com>, 
	Dionna Glaze <dionnaglaze@...gle.com>, linux-integrity@...r.kernel.org
Subject: Re: [PATCH v4 3/4] tpm: add SNP SVSM vTPM driver

On Thu, Mar 27, 2025 at 01:57:31PM +0200, Jarkko Sakkinen wrote:
>On Thu, Mar 27, 2025 at 01:53:59PM +0200, Jarkko Sakkinen wrote:
>> On Thu, Mar 27, 2025 at 11:03:07AM +0100, Stefano Garzarella wrote:
>> > On Wed, Mar 26, 2025 at 09:30:53PM +0200, Jarkko Sakkinen wrote:
>> > > On Mon, Mar 24, 2025 at 11:46:48AM +0100, Stefano Garzarella wrote:

[...]

>> > > > +
>> > > > +static struct tpm_class_ops tpm_chip_ops = {
>> > > > +	.flags = TPM_OPS_AUTO_STARTUP,
>> > > > +	.recv = tpm_svsm_recv,
>> > > > +	.send = tpm_svsm_send,
>> > > > +	.cancel = tpm_svsm_cancel,
>> > > > +	.status = tpm_svsm_status,
>> > > > +	.req_complete_mask = 0,
>> > > > +	.req_complete_val = 0,
>> > > > +	.req_canceled = tpm_svsm_req_canceled,
>> > >
>> > > If this was bundled with the patch set, this would short a lot:
>> > >
>> > > https://lore.kernel.org/linux-integrity/20250326161838.123606-1-jarkko@kernel.org/T/#u
>> > >
>> > > So maybe for v5? Including this patch does not take send_recv()
>> > > out of consideration, it is just smart thing to do in all cases.
>> > >
>> > > It would be probably easiest to roll out my patch together with
>> > > rest of the patch set.
>> >
>> > Yeah, I agree. I'll include it in this series and adapt this patch on top of
>> > it.
>>
>> Yeah, and you could simplify to goal in the other patch set: it's about
>> avoiding double-copy of a buffer.

Yep, agree!

>>
>> It's a totally legit argument that we can measure. So in the end this
>> will help out landing that too because it takes away the extra cruft
>> and streamlines the goal.
>
>... IMHO there is this unwritten law for upstreaming kernel features
>that goes something like "further the goals are from white papers,
>closer they are to mainline" ;-)

:-D I'll make a note of it!

Thanks,
Stefano