Merge tag 'kvm-x86-ciphertext-6.18' of https://github.com/kvm-x86/linux into HEAD

KVM SEV-SNP CipherText Hiding support for 6.18

Add support for SEV-SNP's CipherText Hiding, an opt-in feature that prevents
unauthorized CPU accesses from reading the ciphertext of SNP guest private
memory, e.g. to attempt an offline attack.  Instead of ciphertext, the CPU
will always read back all FFs when CipherText Hiding is enabled.

Add new module parameter to the KVM module to enable CipherText Hiding and
control the number of ASIDs that can be used for VMs with CipherText Hiding,
which is in effect the number of SNP VMs.  When CipherText Hiding is enabled,
the shared SEV-ES/SEV-SNP ASID space is split into separate ranges for SEV-ES
and SEV-SNP guests, i.e. ASIDs that can be used for CipherText Hiding cannot
be used to run SEV-ES guests.

2 files changed, 51 insertions, 3 deletions

diff --git a/include/linux/psp-sev.h b/include/linux/psp-sev.h
index 0f5f94137f6d..e0dbcb4b4fd9 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,
 };
@@ -747,10 +748,13 @@ 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 rsvd:28;
 	u32 rsvd1;
 	u64 list_paddr;
-	u8  rsvd2[48];
+	u16 max_snp_asid;
+	u8  rsvd2[46];
 } __packed;
 
 /**
@@ -799,10 +803,13 @@ struct sev_data_snp_shutdown_ex {
  * @probe: True if this is being called as part of CCP module probe, which
  *  will defer SEV_INIT/SEV_INIT_EX firmware initialization until needed
  *  unless psp_init_on_probe module param is set
+ * @max_snp_asid: When non-zero, enable ciphertext hiding and specify the
+ *  maximum ASID that can be used for an SEV-SNP guest.
  */
 struct sev_platform_init_args {
 	int error;
 	bool probe;
+	unsigned int max_snp_asid;
 };
 
 /**
@@ -814,6 +821,36 @@ 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 : System Physical Address 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;
+
+#define SNP_CIPHER_TEXT_HIDING_SUPPORTED	BIT(3)
+
 #ifdef CONFIG_CRYPTO_DEV_SP_PSP
 
 /**
@@ -957,6 +994,7 @@ void *psp_copy_user_blob(u64 uaddr, u32 len);
 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);
 
 #else	/* !CONFIG_CRYPTO_DEV_SP_PSP */
 
@@ -993,6 +1031,8 @@ static inline void snp_free_firmware_page(void *addr) { }
 
 static inline void sev_platform_shutdown(void) { }
 
+static inline bool sev_is_snp_ciphertext_hiding_supported(void) { return false; }
+
 #endif	/* CONFIG_CRYPTO_DEV_SP_PSP */
 
 #endif	/* __PSP_SEV_H__ */
diff --git a/include/uapi/linux/psp-sev.h b/include/uapi/linux/psp-sev.h
index eeb20dfb1fda..c2fd324623c4 100644
--- a/include/uapi/linux/psp-sev.h
+++ b/include/uapi/linux/psp-sev.h
@@ -185,6 +185,10 @@ 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: whether SNP_FEATURE_INFO command is available
+ * @rapl_dis: whether RAPL is disabled
+ * @ciphertext_hiding_cap: whether platform has ciphertext hiding capability
+ * @ciphertext_hiding_en: whether ciphertext hiding is enabled
  * @rsvd1: reserved
  * @guest_count: the number of guest currently managed by the firmware
  * @current_tcb_version: current TCB version
@@ -200,7 +204,11 @@ 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 rapl_dis:1;		/* Out */
+	__u32 ciphertext_hiding_cap:1;	/* Out */
+	__u32 ciphertext_hiding_en:1;	/* Out */
+	__u32 rsvd1:25;
 	__u32 guest_count;		/* Out */
 	__u64 current_tcb_version;	/* Out */
 	__u64 reported_tcb_version;	/* Out */