linux-kernel - Re: [PATCH v8 06/16] virt: sev-guest: Move SNP Guest command mutex

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Message-ID: <6a7a8892-bb8d-4f03-a802-d7eee48045b5@amd.com>
Date: Tue, 23 Apr 2024 09:52:41 +0530
From: "Nikunj A. Dadhania" <nikunj@....com>
To: Borislav Petkov <bp@...en8.de>
Cc: linux-kernel@...r.kernel.org, thomas.lendacky@....com, x86@...nel.org,
 kvm@...r.kernel.org, mingo@...hat.com, tglx@...utronix.de,
 dave.hansen@...ux.intel.com, pgonda@...gle.com, seanjc@...gle.com,
 pbonzini@...hat.com
Subject: Re: [PATCH v8 06/16] virt: sev-guest: Move SNP Guest command mutex

On 4/22/2024 6:30 PM, Borislav Petkov wrote:
> On Thu, Feb 15, 2024 at 05:01:18PM +0530, Nikunj A Dadhania wrote:
>> SNP command mutex is used to serialize the shared buffer access, command
>> handling and message sequence number races. Move the SNP guest command
>> mutex out of the sev guest driver and provide accessors to sev-guest
> 
> And why in the hell are we doing this?

SNP guest messaging will be moving as part of sev.c, and Secure TSC code
will use this mutex.

> Always, *ALWAYS* make sure a patch's commit message answers *why*
> a change is done. This doesn't explain why so I'm reading "just because"
> and "just because" doesn't fly.

Sure, will change.

> 
>> driver. Remove multiple lockdep check in sev-guest driver, next patch adds
>> a single lockdep check in snp_send_guest_request().
> 
> The concept of "next patch" is meaningless once the patch is in git.

Sure. As direct access to the mutex was not available now, I had removed lockdep
check here and documented that lockdep gets added at later point.

Regards
Nikunj