From: Ashish Kalra <ashish.kalra@xxxxxxx>
The FEATURE_INFO command provides host and guests a programmatic means
to learn about the supported features of the currently loaded firmware.
FEATURE_INFO command leverages the same mechanism as the CPUID instruction.
Instead of using the CPUID instruction to retrieve Fn8000_0024,
software can use FEATURE_INFO.
Host/Hypervisor would use the FEATURE_INFO command, while guests would
actually issue the CPUID instruction.
The hypervisor can provide Fn8000_0024 values to the guest via the CPUID
page in SNP_LAUNCH_UPDATE. As with all CPUID output recorded in that page,
the hypervisor can filter Fn8000_0024. The firmware will examine
Fn8000_0024 and apply its CPUID policy.
During CCP module initialization, after firmware update, the SNP
platform status and feature information from CPUID 0x8000_0024,
sub-function 0, are cached in the sev_device structure.
Signed-off-by: Ashish Kalra <ashish.kalra@xxxxxxx>
---
drivers/crypto/ccp/sev-dev.c | 47 ++++++++++++++++++++++++++++++++++++
drivers/crypto/ccp/sev-dev.h | 3 +++
include/linux/psp-sev.h | 29 ++++++++++++++++++++++
3 files changed, 79 insertions(+)
diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
index af018afd9cd7..564daf748293 100644
--- a/drivers/crypto/ccp/sev-dev.c
+++ b/drivers/crypto/ccp/sev-dev.c
@@ -223,6 +223,7 @@ 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 snp_feature_info);
default: return 0;
}
@@ -1063,6 +1064,50 @@ static void snp_set_hsave_pa(void *arg)
wrmsrl(MSR_VM_HSAVE_PA, 0);
}
+static void snp_get_platform_data(void)
+{
+ struct sev_device *sev = psp_master->sev_data;
+ struct sev_data_snp_feature_info snp_feat_info;
+ struct snp_feature_info *feat_info;
+ struct sev_data_snp_addr buf;
+ int error = 0, rc;
+
+ if (!cc_platform_has(CC_ATTR_HOST_SEV_SNP))
+ return;
+
+ /*
+ * The output buffer must be firmware page if SEV-SNP is
+ * initialized.
+ */
+ if (sev->snp_initialized)
+ return;
+
+ buf.address = __psp_pa(&sev->snp_plat_status);
+ rc = __sev_do_cmd_locked(SEV_CMD_SNP_PLATFORM_STATUS, &buf, &error);
+
+ /*
+ * Do feature discovery of the currently loaded firmware,
+ * and cache feature information from CPUID 0x8000_0024,
+ * sub-function 0.
+ */
+ if (!rc && sev->snp_plat_status.feature_info) {
+ /*
+ * Use dynamically allocated structure for the SNP_FEATURE_INFO
+ * command to handle any alignment and page boundary check
+ * requirements.
+ */
+ feat_info = kzalloc(sizeof(*feat_info), GFP_KERNEL);
+ 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_locked(SEV_CMD_SNP_FEATURE_INFO, &snp_feat_info, &error);
+ if (!rc)
+ sev->feat_info = *feat_info;
+ kfree(feat_info);
+ }
+}
+
static int snp_filter_reserved_mem_regions(struct resource *rs, void *arg)
{
struct sev_data_range_list *range_list = arg;
@@ -2415,6 +2460,8 @@ void sev_pci_init(void)
api_major, api_minor, build,
sev->api_major, sev->api_minor, sev->build);
+ snp_get_platform_data();
+
/* Initialize the platform */
args.probe = true;
rc = sev_platform_init(&args);
diff --git a/drivers/crypto/ccp/sev-dev.h b/drivers/crypto/ccp/sev-dev.h
index 3e4e5574e88a..1c1a51e52d2b 100644
--- a/drivers/crypto/ccp/sev-dev.h
+++ b/drivers/crypto/ccp/sev-dev.h
@@ -57,6 +57,9 @@ struct sev_device {
bool cmd_buf_backup_active;
bool snp_initialized;
+
+ struct sev_user_data_snp_status snp_plat_status;
+ struct snp_feature_info feat_info;
};
int sev_dev_init(struct psp_device *psp);
diff --git a/include/linux/psp-sev.h b/include/linux/psp-sev.h
index 903ddfea8585..6068a89839e1 100644
--- a/include/linux/psp-sev.h
+++ b/include/linux/psp-sev.h
@@ -107,6 +107,7 @@ enum sev_cmd {
SEV_CMD_SNP_DOWNLOAD_FIRMWARE_EX = 0x0CA,
SEV_CMD_SNP_COMMIT = 0x0CB,
SEV_CMD_SNP_VLEK_LOAD = 0x0CD,
+ SEV_CMD_SNP_FEATURE_INFO = 0x0CE,
SEV_CMD_MAX,
};
@@ -812,6 +813,34 @@ struct sev_data_snp_commit {
u32 len;
} __packed;
+/**
+ * struct sev_data_snp_feature_info - SEV_SNP_FEATURE_INFO structure
+ *
+ * @length: len of the command buffer read by the PSP
+ * @ecx_in: subfunction index
+ * @feature_info_paddr : SPA of the FEATURE_INFO structure
+ */
+struct sev_data_snp_feature_info {
+ u32 length;
+ u32 ecx_in;
+ u64 feature_info_paddr;
+} __packed;
+
+/**
+ * struct feature_info - FEATURE_INFO structure
+ *
+ * @eax: output of SNP_FEATURE_INFO command
+ * @ebx: output of SNP_FEATURE_INFO command
+ * @ecx: output of SNP_FEATURE_INFO command
+ * #edx: output of SNP_FEATURE_INFO command
+ */
+struct snp_feature_info {
+ u32 eax;
+ u32 ebx;
+ u32 ecx;
+ u32 edx;
+} __packed;
+
#ifdef CONFIG_CRYPTO_DEV_SP_PSP
/**
--
2.34.1
