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virt: sev-guest: Remove is_vmpck_empty() helper

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Remove is_vmpck_empty() which uses a local array allocation to check if the
VMPCK is empty and replace it with memchr_inv() to directly determine if the
VMPCK is empty without additional memory allocation.

  [ bp: Massage commit message. ]

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/20250106124633.1418972-2-nikunj@amd.com
This commit is contained in:
Nikunj A Dadhania
2025-01-06 18:16:21 +05:30
committed by Borislav Petkov (AMD)
parent 21fc6178e9
commit 8234177d20
1 changed files with 2 additions and 12 deletions
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14
drivers/virt/coco/sev-guest/sev-guest.c
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@@ -63,16 +63,6 @@ MODULE_PARM_DESC(vmpck_id, "The VMPCK ID to use when communicating with the PSP.
/* Mutex to serialize the shared buffer access and command handling. */
static DEFINE_MUTEX(snp_cmd_mutex);
static bool is_vmpck_empty(struct snp_msg_desc *mdesc)
{
char zero_key[VMPCK_KEY_LEN] = {0};
if (mdesc->vmpck)
return !memcmp(mdesc->vmpck, zero_key, VMPCK_KEY_LEN);
return true;
}
/*
* If an error is received from the host or AMD Secure Processor (ASP) there
* are two options. Either retry the exact same encrypted request or discontinue
@@ -335,7 +325,7 @@ static int snp_send_guest_request(struct snp_msg_desc *mdesc, struct snp_guest_r
guard(mutex)(&snp_cmd_mutex);
/* Check if the VMPCK is not empty */
if (is_vmpck_empty(mdesc)) {
if (!mdesc->vmpck || !memchr_inv(mdesc->vmpck, 0, VMPCK_KEY_LEN)) {
pr_err_ratelimited("VMPCK is disabled\n");
return -ENOTTY;
}
@@ -1024,7 +1014,7 @@ static int __init sev_guest_probe(struct platform_device *pdev)
}
/* Verify that VMPCK is not zero. */
if (is_vmpck_empty(mdesc)) {
if (!memchr_inv(mdesc->vmpck, 0, VMPCK_KEY_LEN)) {
dev_err(dev, "Empty VMPCK%d communication key\n", vmpck_id);
goto e_unmap;
}