[v16] Add Secure TSC support for SNP guests

[PATCH v16 02/13] virt: sev-guest: Replace GFP_KERNEL_ACCOUNT with GFP_KERNEL

Posted by Nikunj A Dadhania 8 months, 1 week ago

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@alien8.de>
Signed-off-by: Nikunj A Dadhania <nikunj@amd.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;
 
-- 
2.34.1

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

Posted by Tom Lendacky 8 months, 1 week ago

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@alien8.de>
> Signed-off-by: Nikunj A Dadhania <nikunj@amd.com>

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

[tip: x86/sev] virt: sev-guest: Replace GFP_KERNEL_ACCOUNT with GFP_KERNEL

Posted by tip-bot2 for Nikunj A Dadhania 8 months, 1 week ago

The following commit has been merged into the x86/sev branch of tip:

Commit-ID:     864884a0c29cc610a859b5210158112fd8675fe1
Gitweb:        https://git.kernel.org/tip/864884a0c29cc610a859b5210158112fd8675fe1
Author:        Nikunj A Dadhania <nikunj@amd.com>
AuthorDate:    Mon, 06 Jan 2025 18:16:22 +05:30
Committer:     Borislav Petkov (AMD) <bp@alien8.de>
CommitterDate: Tue, 07 Jan 2025 10:26:20 +01:00

virt: sev-guest: Replace GFP_KERNEL_ACCOUNT with GFP_KERNEL

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@alien8.de>
Signed-off-by: Nikunj A Dadhania <nikunj@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20250106124633.1418972-3-nikunj@amd.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 62328d0..250ce92 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;