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crypto: ccp - Add support for SNP_FEATURE_INFO command

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The FEATURE_INFO command provides hypervisors with a programmatic means
to learn about the supported features of the currently loaded firmware.
This command mimics the CPUID instruction relative to sub-leaf input and
the four unsigned integer output values. To obtain information
regarding the features present in the currently loaded SEV firmware,
use the SNP_FEATURE_INFO command.

Cache the SNP platform status and feature information from CPUID
0x8000_0024 in the sev_device structure. If SNP is enabled, utilize
this cached SNP platform status for the API major, minor and build
version.

Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Ashish Kalra <ashish.kalra@amd.com>
Reviewed-by: Kim Phillips <kim.phillips@amd.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Ashish Kalra
2025-07-21 14:13:10 +00:00
committed by Herbert Xu
parent 459daec42e
commit 33cfb80d19
3 changed files with 104 additions and 0 deletions
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72
drivers/crypto/ccp/sev-dev.c
View File

@@ -233,6 +233,7 @@ static int sev_cmd_buffer_len(int cmd)
case SEV_CMD_SNP_GUEST_REQUEST: return sizeof(struct sev_data_snp_guest_request);
case SEV_CMD_SNP_CONFIG: return sizeof(struct sev_user_data_snp_config);
case SEV_CMD_SNP_COMMIT: return sizeof(struct sev_data_snp_commit);
case SEV_CMD_SNP_FEATURE_INFO: return sizeof(struct sev_data_snp_feature_info);
default: return 0;
}
@@ -1073,6 +1074,67 @@ static void snp_set_hsave_pa(void *arg)
wrmsrq(MSR_VM_HSAVE_PA, 0);
}
static int snp_get_platform_data(struct sev_device *sev, int *error)
{
struct sev_data_snp_feature_info snp_feat_info;
struct snp_feature_info *feat_info;
struct sev_data_snp_addr buf;
struct page *page;
int rc;
/*
* This function is expected to be called before SNP is
* initialized.
*/
if (sev->snp_initialized)
return -EINVAL;
buf.address = __psp_pa(&sev->snp_plat_status);
rc = sev_do_cmd(SEV_CMD_SNP_PLATFORM_STATUS, &buf, error);
if (rc) {
dev_err(sev->dev, "SNP PLATFORM_STATUS command failed, ret = %d, error = %#x\n",
rc, *error);
return rc;
}
sev->api_major = sev->snp_plat_status.api_major;
sev->api_minor = sev->snp_plat_status.api_minor;
sev->build = sev->snp_plat_status.build_id;
/*
* Do feature discovery of the currently loaded firmware,
* and cache feature information from CPUID 0x8000_0024,
* sub-function 0.
*/
if (!sev->snp_plat_status.feature_info)
return 0;
/*
* Use dynamically allocated structure for the SNP_FEATURE_INFO
* command to ensure structure is 8-byte aligned, and does not
* cross a page boundary.
*/
page = alloc_page(GFP_KERNEL);
if (!page)
return -ENOMEM;
feat_info = page_address(page);
snp_feat_info.length = sizeof(snp_feat_info);
snp_feat_info.ecx_in = 0;
snp_feat_info.feature_info_paddr = __psp_pa(feat_info);
rc = sev_do_cmd(SEV_CMD_SNP_FEATURE_INFO, &snp_feat_info, error);
if (!rc)
sev->snp_feat_info_0 = *feat_info;
else
dev_err(sev->dev, "SNP FEATURE_INFO command failed, ret = %d, error = %#x\n",
rc, *error);
__free_page(page);
return rc;
}
static int snp_filter_reserved_mem_regions(struct resource *rs, void *arg)
{
struct sev_data_range_list *range_list = arg;
@@ -1599,6 +1661,16 @@ static int sev_get_api_version(void)
struct sev_user_data_status status;
int error = 0, ret;
/*
* Cache SNP platform status and SNP feature information
* if SNP is available.
*/
if (cc_platform_has(CC_ATTR_HOST_SEV_SNP)) {
ret = snp_get_platform_data(sev, &error);
if (ret)
return 1;
}
ret = sev_platform_status(&status, &error);
if (ret) {
dev_err(sev->dev,