[PATCH v3 3/4] crypto: ccp: Add support to enable CipherTextHiding on SNP_INIT_EX

[Ashish Kalra <Ashish.Kalra@xxxxxxx>]

From: Ashish Kalra <ashish.kalra@xxxxxxx>

Ciphertext hiding needs to be enabled on SNP_INIT_EX.

Add two new arguments to sev_platform_init_args to allow KVM
module to specify during SNP initialization if CipherTextHiding
feature is to be enabled and the maximum ASID usable for an
SEV-SNP guest when CipherTextHiding feature is enabled.

Add new API interface to indicate if SEV-SNP CipherTextHiding
feature is supported and enabled in the Platform/BIOS.

Signed-off-by: Ashish Kalra <ashish.kalra@xxxxxxx>
---
 drivers/crypto/ccp/sev-dev.c | 31 ++++++++++++++++++++++++++++---
 include/linux/psp-sev.h      | 18 ++++++++++++++++--
 2 files changed, 44 insertions(+), 5 deletions(-)

diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
index f4f8a8905115..ca4b156598de 100644
--- a/drivers/crypto/ccp/sev-dev.c
+++ b/drivers/crypto/ccp/sev-dev.c
@@ -1073,6 +1073,25 @@ static void snp_set_hsave_pa(void *arg)
 	wrmsrq(MSR_VM_HSAVE_PA, 0);
 }
 
+bool is_sev_snp_ciphertext_hiding_supported(void)
+{
+	struct psp_device *psp = psp_master;
+	struct sev_device *sev;
+
+	sev = psp->sev_data;
+
+	/*
+	 * Check if CipherTextHiding feature is supported and enabled
+	 * in the Platform/BIOS.
+	 */
+	if ((sev->feat_info.ecx & SNP_CIPHER_TEXT_HIDING_SUPPORTED) &&
+	    sev->snp_plat_status.ciphertext_hiding_cap)
+		return true;
+
+	return false;
+}
+EXPORT_SYMBOL_GPL(is_sev_snp_ciphertext_hiding_supported);
+
 static void snp_get_platform_data(void)
 {
 	struct sev_device *sev = psp_master->sev_data;
@@ -1147,7 +1166,7 @@ static int snp_filter_reserved_mem_regions(struct resource *rs, void *arg)
 	return 0;
 }
 
-static int __sev_snp_init_locked(int *error)
+static int __sev_snp_init_locked(int *error, bool cipher_text_hiding_en, unsigned int snp_max_snp_asid)
 {
 	struct psp_device *psp = psp_master;
 	struct sev_data_snp_init_ex data;
@@ -1208,6 +1227,12 @@ static int __sev_snp_init_locked(int *error)
 		}
 
 		memset(&data, 0, sizeof(data));
+
+		if (cipher_text_hiding_en) {
+			data.ciphertext_hiding_en = 1;
+			data.max_snp_asid = snp_max_snp_asid;
+		}
+
 		data.init_rmp = 1;
 		data.list_paddr_en = 1;
 		data.list_paddr = __psp_pa(snp_range_list);
@@ -1392,7 +1417,7 @@ static int _sev_platform_init_locked(struct sev_platform_init_args *args)
 	if (sev->state == SEV_STATE_INIT)
 		return 0;
 
-	rc = __sev_snp_init_locked(&args->error);
+	rc = __sev_snp_init_locked(&args->error, args->cipher_text_hiding_en, args->snp_max_snp_asid);
 	if (rc && rc != -ENODEV)
 		return rc;
 
@@ -1475,7 +1500,7 @@ static int snp_move_to_init_state(struct sev_issue_cmd *argp, bool *shutdown_req
 {
 	int error, rc;
 
-	rc = __sev_snp_init_locked(&error);
+	rc = __sev_snp_init_locked(&error, false, 0);
 	if (rc) {
 		argp->error = SEV_RET_INVALID_PLATFORM_STATE;
 		return rc;
diff --git a/include/linux/psp-sev.h b/include/linux/psp-sev.h
index 0149d4a6aceb..af45e3e372f5 100644
--- a/include/linux/psp-sev.h
+++ b/include/linux/psp-sev.h
@@ -746,10 +746,13 @@ 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;
 
 /**
@@ -798,10 +801,16 @@ 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
+ *  @cipher_text_hiding_en: True if SEV-SNP CipherTextHiding support is
+ *  enabled
+ *  @snp_max_snp_asid: maximum ASID usable for SEV-SNP guest if
+ *  CipherTextHiding is enabled
  */
 struct sev_platform_init_args {
 	int error;
 	bool probe;
+	bool cipher_text_hiding_en;
+	unsigned int snp_max_snp_asid;
 };
 
 /**
@@ -841,6 +850,8 @@ struct snp_feature_info {
 	u32 edx;
 } __packed;
 
+#define SNP_CIPHER_TEXT_HIDING_SUPPORTED	BIT(3)
+
 #ifdef CONFIG_CRYPTO_DEV_SP_PSP
 
 /**
@@ -984,6 +995,7 @@ 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 is_sev_snp_ciphertext_hiding_supported(void);
 
 #else	/* !CONFIG_CRYPTO_DEV_SP_PSP */
 
@@ -1020,6 +1032,8 @@ static inline void snp_free_firmware_page(void *addr) { }
 
 static inline void sev_platform_shutdown(void) { }
 
+static inline bool is_sev_snp_ciphertext_hiding_supported(void) { return FALSE; }
+
 #endif	/* CONFIG_CRYPTO_DEV_SP_PSP */
 
 #endif	/* __PSP_SEV_H__ */
-- 
2.34.1