Re: [PATCH v11 06/20] x86/sev: Handle failures from snp_init()

[Borislav Petkov]

On Wed, Jul 31, 2024 at 08:37:57PM +0530, Nikunj A Dadhania wrote:
> Address the ignored failures from snp_init() in sme_enable(). Add error
> handling for scenarios where snp_init() fails to retrieve the SEV-SNP CC
> blob or encounters issues while parsing the CC blob.

Is this a real issue you've encountered or?

> This change ensures

Avoid having "This patch" or "This commit" or "This <whatever>" in the commit
message. It is tautologically useless.

Also, do

$ git grep 'This patch' Documentation/process

for more details.

> that SNP guests will error out early, preventing delayed error reporting or
> undefined behavior.
> 
> Signed-off-by: Nikunj A Dadhania <nikunj@xxxxxxx>
> ---
>  arch/x86/mm/mem_encrypt_identity.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/arch/x86/mm/mem_encrypt_identity.c b/arch/x86/mm/mem_encrypt_identity.c
> index ac33b2263a43..e83b363c5e68 100644
> --- a/arch/x86/mm/mem_encrypt_identity.c
> +++ b/arch/x86/mm/mem_encrypt_identity.c
> @@ -535,6 +535,13 @@ void __head sme_enable(struct boot_params *bp)
>  	if (snp && !(msr & MSR_AMD64_SEV_SNP_ENABLED))
>  		snp_abort();
>  
> +	/*
> +	 * The SEV-SNP CC blob should be present and parsing CC blob should
> +	 * succeed when SEV-SNP is enabled.
> +	 */
> +	if (!snp && (msr & MSR_AMD64_SEV_SNP_ENABLED))
> +		snp_abort();

Any chance you could combine the above and this test?

Perhaps look around at the code before adding your check - there might be some
opportunity for aggregation and improvement...

-- 
Regards/Gruss,
    Boris.

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