linux-kernel - Re: [PATCH v2] crypto: ccp: Abort doing SEV INIT if SNP INIT fails

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Message-ID: <93e7bd21-b41f-8d78-f9d1-1868e944efc6@amd.com>
Date: Tue, 18 Mar 2025 15:29:32 -0500
From: Tom Lendacky <thomas.lendacky@....com>
To: Ashish Kalra <Ashish.Kalra@....com>, seanjc@...gle.com,
 pbonzini@...hat.com, bp@...en8.de, john.allen@....com,
 herbert@...dor.apana.org.au, davem@...emloft.net
Cc: michael.roth@....com, kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-crypto@...r.kernel.org, linux-coco@...ts.linux.dev
Subject: Re: [PATCH v2] crypto: ccp: Abort doing SEV INIT if SNP INIT fails

On 3/18/25 15:07, Ashish Kalra wrote:
> From: Ashish Kalra <ashish.kalra@....com>
> 
> If SNP host support (SYSCFG.SNPEn) is set, then the RMP table must
> be initialized before calling SEV INIT.
> 
> In other words, if SNP_INIT(_EX) is not issued or fails then
> SEV INIT will fail if SNP host support (SYSCFG.SNPEn) is enabled.
> 
> Fixes: 1ca5614b84eed ("crypto: ccp: Add support to initialize the AMD-SP for SEV-SNP")

Just wondering if this really needs a Fixes: tag. Either way SNP and SEV
won't be initialized, you're just returning earlier with an error code
rather than attempting the SEV_INIT(_EX) and getting back a failing
error code.

Thanks,
Tom

> Signed-off-by: Ashish Kalra <ashish.kalra@....com>
> 
> v2:
> - Fix commit logs.
> ---
>  drivers/crypto/ccp/sev-dev.c | 7 ++-----
>  1 file changed, 2 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
> index 2e87ca0e292a..a0e3de94704e 100644
> --- a/drivers/crypto/ccp/sev-dev.c
> +++ b/drivers/crypto/ccp/sev-dev.c
> @@ -1112,7 +1112,7 @@ static int __sev_snp_init_locked(int *error)
>  	if (!sev_version_greater_or_equal(SNP_MIN_API_MAJOR, SNP_MIN_API_MINOR)) {
>  		dev_dbg(sev->dev, "SEV-SNP support requires firmware version >= %d:%d\n",
>  			SNP_MIN_API_MAJOR, SNP_MIN_API_MINOR);
> -		return 0;
> +		return -EOPNOTSUPP;
>  	}
>  
>  	/* SNP_INIT requires MSR_VM_HSAVE_PA to be cleared on all CPUs. */
> @@ -1325,12 +1325,9 @@ static int _sev_platform_init_locked(struct sev_platform_init_args *args)
>  	 */
>  	rc = __sev_snp_init_locked(&args->error);
>  	if (rc && rc != -ENODEV) {
> -		/*
> -		 * Don't abort the probe if SNP INIT failed,
> -		 * continue to initialize the legacy SEV firmware.
> -		 */
>  		dev_err(sev->dev, "SEV-SNP: failed to INIT rc %d, error %#x\n",
>  			rc, args->error);
> +		return rc;
>  	}
>  
>  	/* Defer legacy SEV/SEV-ES support if allowed by caller/module. */