[RFC PATCH 06/21] crypto: ccp: Enable SEV-TIO feature in the PSP when supported

Alexey Kardashevskiy
2024-08-23T13:29:12Z

The PSP advertises the SEV-TIO support via the FEATURE_INFO command
support of which is advertised via SNP_PLATFORM_STATUS.

Add FEATURE_INFO and use it to detect the TIO support in the PSP.
If present, enable TIO in the SNP_INIT_EX call.

While at this, add new bits to sev_data_snp_init_ex() from SEV-SNP 1.55.

Note that this tests the PSP firmware support but not if the feature
is enabled in the BIOS.

While at this, add new sev_data_snp_shutdown_ex::x86_snp_shutdown

Signed-off-by: Alexey Kardashevskiy <aik@amd.com>
---
include/linux/psp-sev.h | 31 ++++++++-
include/uapi/linux/psp-sev.h | 4 +-
drivers/crypto/ccp/sev-dev.c | 73 ++++++++++++++++++++
3 files changed, 104 insertions(+), 4 deletions(-)

diff --git a/include/linux/psp-sev.h b/include/linux/psp-sev.h
index 52d5ee101d3a..1d63044f66be 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,
};
@@ -584,6 +585,25 @@ struct sev_data_snp_addr {
u64 address; /* In/Out */
} __packed;

+/**
+ * struct sev_data_snp_feature_info - SEV_CMD_SNP_FEATURE_INFO command params
+ *
+ * @len: length of this struct
+ * @ecx_in: subfunction index of CPUID Fn8000_0024
+ * @feature_info_paddr: physical address of a page with sev_snp_feature_info
+ */
+#define SNP_FEATURE_FN8000_0024_EBX_X00_SEVTIO 1
+
+struct sev_snp_feature_info {
+ u32 eax, ebx, ecx, edx; /* Out */
+} __packed;
+
+struct sev_data_snp_feature_info {
+ u32 length; /* In */
+ u32 ecx_in; /* In */
+ u64 feature_info_paddr; /* In */
+} __packed;
+
/**
* struct sev_data_snp_launch_start - SNP_LAUNCH_START command params
*
@@ -745,10 +765,14 @@ struct sev_data_snp_guest_request {
struct sev_data_snp_init_ex {
u32 init_rmp:1;
u32 list_paddr_en:1;
- u32 rsvd:30;
+ u32 rapl_dis:1;
+ u32 ciphertext_hiding_en:1;
+ u32 tio_en:1;
+ u32 rsvd:27;
u32 rsvd1;
u64 list_paddr;
- u8 rsvd2[48];
+ u16 max_snp_asid;
+ u8 rsvd2[46];
} __packed;

/**
@@ -787,7 +811,8 @@ struct sev_data_range_list {
struct sev_data_snp_shutdown_ex {
u32 len;
u32 iommu_snp_shutdown:1;
- u32 rsvd1:31;
+ u32 x86_snp_shutdown:1;
+ u32 rsvd1:30;
} __packed;

/**
diff --git a/include/uapi/linux/psp-sev.h b/include/uapi/linux/psp-sev.h
index 7d2e10e3cdd5..28ee2a03c2b9 100644
--- a/include/uapi/linux/psp-sev.h
+++ b/include/uapi/linux/psp-sev.h
@@ -214,6 +214,7 @@ struct sev_user_data_get_id2 {
* @mask_chip_id: whether chip id is present in attestation reports or not
* @mask_chip_key: whether attestation reports are signed or not
* @vlek_en: VLEK (Version Loaded Endorsement Key) hashstick is loaded
+ * @feature_info: Indicates that the SNP_FEATURE_INFO command is available
* @rsvd1: reserved
* @guest_count: the number of guest currently managed by the firmware
* @current_tcb_version: current TCB version
@@ -229,7 +230,8 @@ struct sev_user_data_snp_status {
__u32 mask_chip_id:1; /* Out */
__u32 mask_chip_key:1; /* Out */
__u32 vlek_en:1; /* Out */
- __u32 rsvd1:29;
+ __u32 feature_info:1; /* Out */
+ __u32 rsvd1:28;
__u32 guest_count; /* Out */
__u64 current_tcb_version; /* Out */
__u64 reported_tcb_version; /* Out */
diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
index f6eafde584d9..a49fe54b8dd8 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 sev_data_snp_feature_info);
default: return 0;
}

@@ -1125,6 +1126,77 @@ static int snp_platform_status_locked(struct sev_device *sev,
return ret;
}

+static int snp_feature_info_locked(struct sev_device *sev, u32 ecx,
+ struct sev_snp_feature_info *fi, int *psp_ret)
+{
+ struct sev_data_snp_feature_info buf = {
+ .length = sizeof(buf),
+ .ecx_in = ecx,
+ };
+ struct page *status_page;
+ void *data;
+ int ret;
+
+ status_page = alloc_page(GFP_KERNEL_ACCOUNT);
+ if (!status_page)
+ return -ENOMEM;
+
+ data = page_address(status_page);
+
+ if (sev->snp_initialized && rmp_mark_pages_firmware(__pa(data), 1, true)) {
+ ret = -EFAULT;
+ goto cleanup;
+ }
+
+ buf.feature_info_paddr = __psp_pa(data);
+ ret = __sev_do_cmd_locked(SEV_CMD_SNP_FEATURE_INFO, &buf, psp_ret);
+
+ if (sev->snp_initialized && snp_reclaim_pages(__pa(data), 1, true))
+ ret = -EFAULT;
+
+ if (!ret)
+ memcpy(fi, data, sizeof(*fi));
+
+cleanup:
+ __free_pages(status_page, 0);
+ return ret;
+}
+
+static int snp_get_feature_info(struct sev_device *sev, u32 ecx, struct sev_snp_feature_info *fi)
+{
+ struct sev_user_data_snp_status status = { 0 };
+ int psp_ret = 0, ret;
+
+ ret = snp_platform_status_locked(sev, &status, &psp_ret);
+ if (ret)
+ return ret;
+ if (ret != SEV_RET_SUCCESS)
+ return -EFAULT;
+ if (!status.feature_info)
+ return -ENOENT;
+
+ ret = snp_feature_info_locked(sev, ecx, fi, &psp_ret);
+ if (ret)
+ return ret;
+ if (ret != SEV_RET_SUCCESS)
+ return -EFAULT;
+
+ return 0;
+}
+
+static bool sev_tio_present(struct sev_device *sev)
+{
+ struct sev_snp_feature_info fi = { 0 };
+ bool present;
+
+ if (snp_get_feature_info(sev, 0, &fi))
+ return false;
+
+ present = (fi.ebx & SNP_FEATURE_FN8000_0024_EBX_X00_SEVTIO) != 0;
+ dev_info(sev->dev, "SEV-TIO support is %s\n", present ? "present" : "not present");
+ return present;
+}
+
static int __sev_snp_init_locked(int *error)
{
struct psp_device *psp = psp_master;
@@ -1189,6 +1261,7 @@ static int __sev_snp_init_locked(int *error)
data.init_rmp = 1;
data.list_paddr_en = 1;
data.list_paddr = __psp_pa(snp_range_list);
+ data.tio_en = sev_tio_present(sev);
cmd = SEV_CMD_SNP_INIT_EX;
} else {
cmd = SEV_CMD_SNP_INIT;
--
2.45.2