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crypto: ccp - Add an API to return the supported SEV-SNP policy bits

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Supported policy bits are dependent on the level of SEV firmware that is
currently running. Create an API to return the supported policy bits for
the current level of firmware.

Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Link: https://patch.msgid.link/e3f711366ddc22e3dd215c987fd2e28dc1c07f54.1761593632.git.thomas.lendacky@amd.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Tom Lendacky 2025-10-27 14:33:50 -05:00 committed by Sean Christopherson
parent ce62118a2e
commit c9434e64e8
2 changed files with 55 additions and 0 deletions
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37
drivers/crypto/ccp/sev-dev.c
View File

@ -2777,6 +2777,43 @@ void sev_platform_shutdown(void)
}
EXPORT_SYMBOL_GPL(sev_platform_shutdown);
u64 sev_get_snp_policy_bits(void)
{
struct psp_device *psp = psp_master;
struct sev_device *sev;
u64 policy_bits;
if (!cc_platform_has(CC_ATTR_HOST_SEV_SNP))
return 0;
if (!psp || !psp->sev_data)
return 0;
sev = psp->sev_data;
policy_bits = SNP_POLICY_MASK_BASE;
if (sev->snp_plat_status.feature_info) {
if (sev->snp_feat_info_0.ecx & SNP_RAPL_DISABLE_SUPPORTED)
policy_bits |= SNP_POLICY_MASK_RAPL_DIS;
if (sev->snp_feat_info_0.ecx & SNP_CIPHER_TEXT_HIDING_SUPPORTED)
policy_bits |= SNP_POLICY_MASK_CIPHERTEXT_HIDING_DRAM;
if (sev->snp_feat_info_0.ecx & SNP_AES_256_XTS_POLICY_SUPPORTED)
policy_bits |= SNP_POLICY_MASK_MEM_AES_256_XTS;
if (sev->snp_feat_info_0.ecx & SNP_CXL_ALLOW_POLICY_SUPPORTED)
policy_bits |= SNP_POLICY_MASK_CXL_ALLOW;
if (sev_version_greater_or_equal(1, 58))
policy_bits |= SNP_POLICY_MASK_PAGE_SWAP_DISABLE;
}
return policy_bits;
}
EXPORT_SYMBOL_GPL(sev_get_snp_policy_bits);
void sev_dev_destroy(struct psp_device *psp)
{
struct sev_device *sev = psp->sev_data;

18
include/linux/psp-sev.h
View File

@ -32,6 +32,20 @@
#define SNP_POLICY_MASK_MIGRATE_MA BIT_ULL(18)
#define SNP_POLICY_MASK_DEBUG BIT_ULL(19)
#define SNP_POLICY_MASK_SINGLE_SOCKET BIT_ULL(20)
#define SNP_POLICY_MASK_CXL_ALLOW BIT_ULL(21)
#define SNP_POLICY_MASK_MEM_AES_256_XTS BIT_ULL(22)
#define SNP_POLICY_MASK_RAPL_DIS BIT_ULL(23)
#define SNP_POLICY_MASK_CIPHERTEXT_HIDING_DRAM BIT_ULL(24)
#define SNP_POLICY_MASK_PAGE_SWAP_DISABLE BIT_ULL(25)
/* Base SEV-SNP policy bitmask for minimum supported SEV firmware version */
#define SNP_POLICY_MASK_BASE (SNP_POLICY_MASK_API_MINOR | \
SNP_POLICY_MASK_API_MAJOR | \
SNP_POLICY_MASK_SMT | \
SNP_POLICY_MASK_RSVD_MBO | \
SNP_POLICY_MASK_MIGRATE_MA | \
SNP_POLICY_MASK_DEBUG | \
SNP_POLICY_MASK_SINGLE_SOCKET)
#define SEV_FW_BLOB_MAX_SIZE 0x4000 /* 16KB */
@ -868,7 +882,10 @@ struct snp_feature_info {
u32 edx;
} __packed;
#define SNP_RAPL_DISABLE_SUPPORTED BIT(2)
#define SNP_CIPHER_TEXT_HIDING_SUPPORTED BIT(3)
#define SNP_AES_256_XTS_POLICY_SUPPORTED BIT(4)
#define SNP_CXL_ALLOW_POLICY_SUPPORTED BIT(5)
#ifdef CONFIG_CRYPTO_DEV_SP_PSP
@ -1014,6 +1031,7 @@ void *snp_alloc_firmware_page(gfp_t mask);
void snp_free_firmware_page(void *addr);
void sev_platform_shutdown(void);
bool sev_is_snp_ciphertext_hiding_supported(void);
u64 sev_get_snp_policy_bits(void);
#else /* !CONFIG_CRYPTO_DEV_SP_PSP */