linux-kernel - Re: [PATCH v2 3/9] crypto: ccp: Reset TMR size at SNP Shutdown

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Message-ID: <433dc629-a84b-470a-8c2f-9bb531a23185@amd.com>
Date: Fri, 27 Dec 2024 20:07:37 +1100
From: Alexey Kardashevskiy <aik@....com>
To: Ashish Kalra <Ashish.Kalra@....com>, seanjc@...gle.com,
 pbonzini@...hat.com, tglx@...utronix.de, mingo@...hat.com, bp@...en8.de,
 dave.hansen@...ux.intel.com, x86@...nel.org, hpa@...or.com,
 thomas.lendacky@....com, john.allen@....com, herbert@...dor.apana.org.au,
 davem@...emloft.net
Cc: michael.roth@....com, dionnaglaze@...gle.com, kvm@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-crypto@...r.kernel.org,
 linux-coco@...ts.linux.dev
Subject: Re: [PATCH v2 3/9] crypto: ccp: Reset TMR size at SNP Shutdown

On 17/12/24 10:58, Ashish Kalra wrote:
> From: Ashish Kalra <ashish.kalra@....com>
> 
> When SEV-SNP is enabled the TMR needs to be 2MB aligned and 2MB sized,
> ensure that TMR size is reset back to default when SNP is shutdown as
> SNP initialization and shutdown as part of some SNP ioctls may leave
> TMR size modified and cause subsequent SEV only initialization to fail.
> 
> Signed-off-by: Ashish Kalra <ashish.kalra@....com>
> ---
>   drivers/crypto/ccp/sev-dev.c | 3 +++
>   1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
> index 0ec2e8191583..9632a9a5c92e 100644
> --- a/drivers/crypto/ccp/sev-dev.c
> +++ b/drivers/crypto/ccp/sev-dev.c
> @@ -1751,6 +1751,9 @@ static int __sev_snp_shutdown_locked(int *error, bool panic)
>   	sev->snp_initialized = false;
>   	dev_dbg(sev->dev, "SEV-SNP firmware shutdown\n");
>   
> +	/* Reset TMR size back to default */
> +	sev_es_tmr_size = SEV_TMR_SIZE;


It is declared as:

static size_t sev_es_tmr_size = SEV_TMR_SIZE;

and then re-assigned again in __sev_snp_init_locked() to the same value 
of SNP_TMR_SIZE. When can sev_es_tmr_size become something else than 
SEV_TMR_SIZE? I did grep 10b2c8a67c4b (kvm/next) and 85ef1ac03941 
(AMDESE/snp-host-latest) but could not find it. Stale code may be? Thanks,


> +
>   	return ret;
>   }
>   

-- 
Alexey