linux-kernel - Re: [PATCH v16 02/13] virt: sev-guest: Replace GFP_KERNEL_ACCOUNT with GFP

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Message-ID: <c5be0341-7d87-8a18-6d17-ee2b0e1bc976@amd.com>
Date: Tue, 7 Jan 2025 12:40:55 -0600
From: Tom Lendacky <thomas.lendacky@....com>
To: Nikunj A Dadhania <nikunj@....com>, linux-kernel@...r.kernel.org,
 bp@...en8.de, x86@...nel.org
Cc: kvm@...r.kernel.org, mingo@...hat.com, tglx@...utronix.de,
 dave.hansen@...ux.intel.com, pgonda@...gle.com, seanjc@...gle.com,
 pbonzini@...hat.com, francescolavra.fl@...il.com
Subject: Re: [PATCH v16 02/13] virt: sev-guest: Replace GFP_KERNEL_ACCOUNT
 with GFP_KERNEL

On 1/6/25 06:46, Nikunj A Dadhania wrote:
> Replace GFP_KERNEL_ACCOUNT with GFP_KERNEL in the sev-guest driver code.
> GFP_KERNEL_ACCOUNT is typically used for accounting untrusted userspace
> allocations. After auditing the sev-guest code, the following changes are
> necessary:
> 
>   * snp_init_crypto(): Use GFP_KERNEL as this is a trusted device probe
>     path.
> 
> Retain GFP_KERNEL_ACCOUNT in the following cases for robustness and
> specific path requirements:
> 
>   * alloc_shared_pages(): Although all allocations are limited, retain
>     GFP_KERNEL_ACCOUNT for future robustness.
> 
>   * get_report() and get_ext_report(): These functions are on the unlocked
>     ioctl path and should continue using GFP_KERNEL_ACCOUNT.
> 
> Suggested-by: Borislav Petkov <bp@...en8.de>
> Signed-off-by: Nikunj A Dadhania <nikunj@....com>

Reviewed-by: Tom Lendacky <thomas.lendacky@....com>

> ---
>  drivers/virt/coco/sev-guest/sev-guest.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/virt/coco/sev-guest/sev-guest.c b/drivers/virt/coco/sev-guest/sev-guest.c
> index 62328d0b2cb6..250ce92d816b 100644
> --- a/drivers/virt/coco/sev-guest/sev-guest.c
> +++ b/drivers/virt/coco/sev-guest/sev-guest.c
> @@ -141,7 +141,7 @@ static struct aesgcm_ctx *snp_init_crypto(u8 *key, size_t keylen)
>  {
>  	struct aesgcm_ctx *ctx;
>  
> -	ctx = kzalloc(sizeof(*ctx), GFP_KERNEL_ACCOUNT);
> +	ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
>  	if (!ctx)
>  		return NULL;
>