[PATCH v2 0/4] x86/sev: Rework SNP Guest Request

[PATCH v2 0/4] x86/sev: Rework SNP Guest Request

[Alexey Kardashevskiy]

Started as a part of the fix for
ae596615d93d ("virt: sev-guest: Reduce the scope of SNP command mutex")

these are the remainder of followup fixes/improvements as
the SNP Guest Request code evolved enough to make it a bit hard to
follow.

Changes:
v2:
* added RBs
* adjusted grammar
* rebased on top of v6.16-rc1


The previous conversation is here:
https://lore.kernel.org/r/20250505141238.4179623-1-aik@amd.com 

This is based on sha1
19272b37aa4f Linus Torvalds "Linux 6.16-rc1".

Please comment. Thanks.



Alexey Kardashevskiy (4):
  virt: sev-guest: Contain snp_guest_request_ioctl in sev-guest
  x86/sev: Allocate request in TSC_INFO_REQ on stack
  x86/sev: Document requirement for linear mapping of Guest Request
    buffers
  x86/sev: Drop unnecessary parameter in snp_issue_guest_request

 arch/x86/include/asm/sev.h              | 10 ++-
 arch/x86/coco/sev/core.c                | 72 +++++++++-----------
 drivers/virt/coco/sev-guest/sev-guest.c |  9 ++-
 3 files changed, 43 insertions(+), 48 deletions(-)

-- 
2.49.0

[PATCH v2 1/4] virt: sev-guest: Contain snp_guest_request_ioctl in sev-guest

[Alexey Kardashevskiy]

SNP Guest Request only uses exitinfo2 which is a return value from GHCB,
has meaning beyond ioctl and therefore belongs to snp_guest_req.

Move exitinfo2 to snp_guest_req, remove snp_guest_request_ioctl from
the SEV platform code.

No functional change intended.

Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
Reviewed-by: Dionna Glaze <dionnaglaze@google.com>
Signed-off-by: Alexey Kardashevskiy <aik@amd.com>
---

Not passing exitinfo2 as a parameter as it's been mentioned on v2:

===
having a struct request which collects all fields you need to pass down or return to callers is the RightThing(tm) to do.
===
---
 arch/x86/include/asm/sev.h              | 10 +++---
 arch/x86/coco/sev/core.c                | 36 +++++++-------------
 drivers/virt/coco/sev-guest/sev-guest.c |  9 +++--
 3 files changed, 23 insertions(+), 32 deletions(-)

diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h
index 58e028d42e41..fbb616fcbfb8 100644
--- a/arch/x86/include/asm/sev.h
+++ b/arch/x86/include/asm/sev.h
@@ -231,6 +231,7 @@ struct snp_guest_req {
 	size_t resp_sz;
 
 	u64 exit_code;
+	u64 exitinfo2;
 	unsigned int vmpck_id;
 	u8 msg_version;
 	u8 msg_type;
@@ -486,8 +487,6 @@ static inline int pvalidate(unsigned long vaddr, bool rmp_psize, bool validate)
 	return rc;
 }
 
-struct snp_guest_request_ioctl;
-
 void setup_ghcb(void);
 void early_snp_set_memory_private(unsigned long vaddr, unsigned long paddr,
 				  unsigned long npages);
@@ -513,8 +512,7 @@ void snp_kexec_begin(void);
 int snp_msg_init(struct snp_msg_desc *mdesc, int vmpck_id);
 struct snp_msg_desc *snp_msg_alloc(void);
 void snp_msg_free(struct snp_msg_desc *mdesc);
-int snp_send_guest_request(struct snp_msg_desc *mdesc, struct snp_guest_req *req,
-			   struct snp_guest_request_ioctl *rio);
+int snp_send_guest_request(struct snp_msg_desc *mdesc, struct snp_guest_req *req);
 
 int snp_svsm_vtpm_send_command(u8 *buffer);
 
@@ -587,8 +585,8 @@ static inline void snp_kexec_begin(void) { }
 static inline int snp_msg_init(struct snp_msg_desc *mdesc, int vmpck_id) { return -1; }
 static inline struct snp_msg_desc *snp_msg_alloc(void) { return NULL; }
 static inline void snp_msg_free(struct snp_msg_desc *mdesc) { }
-static inline int snp_send_guest_request(struct snp_msg_desc *mdesc, struct snp_guest_req *req,
-					 struct snp_guest_request_ioctl *rio) { return -ENODEV; }
+static inline int snp_send_guest_request(struct snp_msg_desc *mdesc,
+					 struct snp_guest_req *req) { return -ENODEV; }
 static inline int snp_svsm_vtpm_send_command(u8 *buffer) { return -ENODEV; }
 static inline void __init snp_secure_tsc_prepare(void) { }
 static inline void __init snp_secure_tsc_init(void) { }
diff --git a/arch/x86/coco/sev/core.c b/arch/x86/coco/sev/core.c
index b6db4e0b936b..cf91cb4e2c47 100644
--- a/arch/x86/coco/sev/core.c
+++ b/arch/x86/coco/sev/core.c
@@ -1389,8 +1389,7 @@ int snp_issue_svsm_attest_req(u64 call_id, struct svsm_call *call,
 }
 EXPORT_SYMBOL_GPL(snp_issue_svsm_attest_req);
 
-static int snp_issue_guest_request(struct snp_guest_req *req, struct snp_req_data *input,
-				   struct snp_guest_request_ioctl *rio)
+static int snp_issue_guest_request(struct snp_guest_req *req, struct snp_req_data *input)
 {
 	struct ghcb_state state;
 	struct es_em_ctxt ctxt;
@@ -1398,7 +1397,7 @@ static int snp_issue_guest_request(struct snp_guest_req *req, struct snp_req_dat
 	struct ghcb *ghcb;
 	int ret;
 
-	rio->exitinfo2 = SEV_RET_NO_FW_CALL;
+	req->exitinfo2 = SEV_RET_NO_FW_CALL;
 
 	/*
 	 * __sev_get_ghcb() needs to run with IRQs disabled because it is using
@@ -1423,8 +1422,8 @@ static int snp_issue_guest_request(struct snp_guest_req *req, struct snp_req_dat
 	if (ret)
 		goto e_put;
 
-	rio->exitinfo2 = ghcb->save.sw_exit_info_2;
-	switch (rio->exitinfo2) {
+	req->exitinfo2 = ghcb->save.sw_exit_info_2;
+	switch (req->exitinfo2) {
 	case 0:
 		break;
 
@@ -1919,8 +1918,7 @@ static int enc_payload(struct snp_msg_desc *mdesc, u64 seqno, struct snp_guest_r
 	return 0;
 }
 
-static int __handle_guest_request(struct snp_msg_desc *mdesc, struct snp_guest_req *req,
-				  struct snp_guest_request_ioctl *rio)
+static int __handle_guest_request(struct snp_msg_desc *mdesc, struct snp_guest_req *req)
 {
 	unsigned long req_start = jiffies;
 	unsigned int override_npages = 0;
@@ -1934,7 +1932,7 @@ static int __handle_guest_request(struct snp_msg_desc *mdesc, struct snp_guest_r
 	 * sequence number must be incremented or the VMPCK must be deleted to
 	 * prevent reuse of the IV.
 	 */
-	rc = snp_issue_guest_request(req, &req->input, rio);
+	rc = snp_issue_guest_request(req, &req->input);
 	switch (rc) {
 	case -ENOSPC:
 		/*
@@ -1987,7 +1985,7 @@ static int __handle_guest_request(struct snp_msg_desc *mdesc, struct snp_guest_r
 	snp_inc_msg_seqno(mdesc);
 
 	if (override_err) {
-		rio->exitinfo2 = override_err;
+		req->exitinfo2 = override_err;
 
 		/*
 		 * If an extended guest request was issued and the supplied certificate
@@ -2005,8 +2003,7 @@ static int __handle_guest_request(struct snp_msg_desc *mdesc, struct snp_guest_r
 	return rc;
 }
 
-int snp_send_guest_request(struct snp_msg_desc *mdesc, struct snp_guest_req *req,
-			   struct snp_guest_request_ioctl *rio)
+int snp_send_guest_request(struct snp_msg_desc *mdesc, struct snp_guest_req *req)
 {
 	u64 seqno;
 	int rc;
@@ -2043,14 +2040,14 @@ int snp_send_guest_request(struct snp_msg_desc *mdesc, struct snp_guest_req *req
 	req->input.resp_gpa = __pa(mdesc->response);
 	req->input.data_gpa = req->certs_data ? __pa(req->certs_data) : 0;
 
-	rc = __handle_guest_request(mdesc, req, rio);
+	rc = __handle_guest_request(mdesc, req);
 	if (rc) {
 		if (rc == -EIO &&
-		    rio->exitinfo2 == SNP_GUEST_VMM_ERR(SNP_GUEST_VMM_ERR_INVALID_LEN))
+		    req->exitinfo2 == SNP_GUEST_VMM_ERR(SNP_GUEST_VMM_ERR_INVALID_LEN))
 			return rc;
 
 		pr_alert("Detected error from ASP request. rc: %d, exitinfo2: 0x%llx\n",
-			 rc, rio->exitinfo2);
+			 rc, req->exitinfo2);
 
 		snp_disable_vmpck(mdesc);
 		return rc;
@@ -2069,7 +2066,6 @@ EXPORT_SYMBOL_GPL(snp_send_guest_request);
 
 static int __init snp_get_tsc_info(void)
 {
-	struct snp_guest_request_ioctl *rio;
 	struct snp_tsc_info_resp *tsc_resp;
 	struct snp_tsc_info_req *tsc_req;
 	struct snp_msg_desc *mdesc;
@@ -2093,13 +2089,9 @@ static int __init snp_get_tsc_info(void)
 	if (!req)
 		goto e_free_tsc_resp;
 
-	rio = kzalloc(sizeof(*rio), GFP_KERNEL);
-	if (!rio)
-		goto e_free_req;
-
 	mdesc = snp_msg_alloc();
 	if (IS_ERR_OR_NULL(mdesc))
-		goto e_free_rio;
+		goto e_free_req;
 
 	rc = snp_msg_init(mdesc, snp_vmpl);
 	if (rc)
@@ -2114,7 +2106,7 @@ static int __init snp_get_tsc_info(void)
 	req->resp_sz = sizeof(*tsc_resp) + AUTHTAG_LEN;
 	req->exit_code = SVM_VMGEXIT_GUEST_REQUEST;
 
-	rc = snp_send_guest_request(mdesc, req, rio);
+	rc = snp_send_guest_request(mdesc, req);
 	if (rc)
 		goto e_request;
 
@@ -2135,8 +2127,6 @@ static int __init snp_get_tsc_info(void)
 	memzero_explicit(tsc_resp, sizeof(*tsc_resp) + AUTHTAG_LEN);
 e_free_mdesc:
 	snp_msg_free(mdesc);
-e_free_rio:
-	kfree(rio);
 e_free_req:
 	kfree(req);
  e_free_tsc_resp:
diff --git a/drivers/virt/coco/sev-guest/sev-guest.c b/drivers/virt/coco/sev-guest/sev-guest.c
index 7a4e2188f109..d2b3ae7113ab 100644
--- a/drivers/virt/coco/sev-guest/sev-guest.c
+++ b/drivers/virt/coco/sev-guest/sev-guest.c
@@ -101,7 +101,8 @@ static int get_report(struct snp_guest_dev *snp_dev, struct snp_guest_request_io
 	req.resp_sz = resp_len;
 	req.exit_code = SVM_VMGEXIT_GUEST_REQUEST;
 
-	rc = snp_send_guest_request(mdesc, &req, arg);
+	rc = snp_send_guest_request(mdesc, &req);
+	arg->exitinfo2 = req.exitinfo2;
 	if (rc)
 		goto e_free;
 
@@ -152,7 +153,8 @@ static int get_derived_key(struct snp_guest_dev *snp_dev, struct snp_guest_reque
 	req.resp_sz = resp_len;
 	req.exit_code = SVM_VMGEXIT_GUEST_REQUEST;
 
-	rc = snp_send_guest_request(mdesc, &req, arg);
+	rc = snp_send_guest_request(mdesc, &req);
+	arg->exitinfo2 = req.exitinfo2;
 	if (rc)
 		return rc;
 
@@ -249,7 +251,8 @@ static int get_ext_report(struct snp_guest_dev *snp_dev, struct snp_guest_reques
 	req.resp_sz = resp_len;
 	req.exit_code = SVM_VMGEXIT_EXT_GUEST_REQUEST;
 
-	ret = snp_send_guest_request(mdesc, &req, arg);
+	ret = snp_send_guest_request(mdesc, &req);
+	arg->exitinfo2 = req.exitinfo2;
 
 	/* If certs length is invalid then copy the returned length */
 	if (arg->vmm_error == SNP_GUEST_VMM_ERR_INVALID_LEN) {
-- 
2.49.0

[tip: x86/sev] virt: sev-guest: Contain snp_guest_request_ioctl in sev-guest

[tip-bot2 for Alexey Kardashevskiy]

The following commit has been merged into the x86/sev branch of tip:

Commit-ID:     3f83ab6f9f1db9e8f0141c0c6b974f40b4aa0dcf
Gitweb:        https://git.kernel.org/tip/3f83ab6f9f1db9e8f0141c0c6b974f40b4aa0dcf
Author:        Alexey Kardashevskiy <aik@amd.com>
AuthorDate:    Wed, 11 Jun 2025 14:08:39 +10:00
Committer:     Borislav Petkov (AMD) <bp@alien8.de>
CommitterDate: Wed, 18 Jun 2025 22:55:30 +02:00

virt: sev-guest: Contain snp_guest_request_ioctl in sev-guest

SNP Guest Request uses only exitinfo2 which is a return value from GHCB, has
meaning beyond ioctl and therefore belongs to struct snp_guest_req.

Move exitinfo2 there and remove snp_guest_request_ioctl from the SEV platform
code.

No functional change intended.

Signed-off-by: Alexey Kardashevskiy <aik@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
Reviewed-by: Dionna Glaze <dionnaglaze@google.com>
Link: https://lore.kernel.org/20250611040842.2667262-2-aik@amd.com
---
 arch/x86/coco/sev/core.c                | 36 ++++++++----------------
 arch/x86/include/asm/sev.h              | 10 ++-----
 drivers/virt/coco/sev-guest/sev-guest.c |  9 ++++--
 3 files changed, 23 insertions(+), 32 deletions(-)

diff --git a/arch/x86/coco/sev/core.c b/arch/x86/coco/sev/core.c
index b6db4e0..cf91cb4 100644
--- a/arch/x86/coco/sev/core.c
+++ b/arch/x86/coco/sev/core.c
@@ -1389,8 +1389,7 @@ int snp_issue_svsm_attest_req(u64 call_id, struct svsm_call *call,
 }
 EXPORT_SYMBOL_GPL(snp_issue_svsm_attest_req);
 
-static int snp_issue_guest_request(struct snp_guest_req *req, struct snp_req_data *input,
-				   struct snp_guest_request_ioctl *rio)
+static int snp_issue_guest_request(struct snp_guest_req *req, struct snp_req_data *input)
 {
 	struct ghcb_state state;
 	struct es_em_ctxt ctxt;
@@ -1398,7 +1397,7 @@ static int snp_issue_guest_request(struct snp_guest_req *req, struct snp_req_dat
 	struct ghcb *ghcb;
 	int ret;
 
-	rio->exitinfo2 = SEV_RET_NO_FW_CALL;
+	req->exitinfo2 = SEV_RET_NO_FW_CALL;
 
 	/*
 	 * __sev_get_ghcb() needs to run with IRQs disabled because it is using
@@ -1423,8 +1422,8 @@ static int snp_issue_guest_request(struct snp_guest_req *req, struct snp_req_dat
 	if (ret)
 		goto e_put;
 
-	rio->exitinfo2 = ghcb->save.sw_exit_info_2;
-	switch (rio->exitinfo2) {
+	req->exitinfo2 = ghcb->save.sw_exit_info_2;
+	switch (req->exitinfo2) {
 	case 0:
 		break;
 
@@ -1919,8 +1918,7 @@ static int enc_payload(struct snp_msg_desc *mdesc, u64 seqno, struct snp_guest_r
 	return 0;
 }
 
-static int __handle_guest_request(struct snp_msg_desc *mdesc, struct snp_guest_req *req,
-				  struct snp_guest_request_ioctl *rio)
+static int __handle_guest_request(struct snp_msg_desc *mdesc, struct snp_guest_req *req)
 {
 	unsigned long req_start = jiffies;
 	unsigned int override_npages = 0;
@@ -1934,7 +1932,7 @@ retry_request:
 	 * sequence number must be incremented or the VMPCK must be deleted to
 	 * prevent reuse of the IV.
 	 */
-	rc = snp_issue_guest_request(req, &req->input, rio);
+	rc = snp_issue_guest_request(req, &req->input);
 	switch (rc) {
 	case -ENOSPC:
 		/*
@@ -1987,7 +1985,7 @@ retry_request:
 	snp_inc_msg_seqno(mdesc);
 
 	if (override_err) {
-		rio->exitinfo2 = override_err;
+		req->exitinfo2 = override_err;
 
 		/*
 		 * If an extended guest request was issued and the supplied certificate
@@ -2005,8 +2003,7 @@ retry_request:
 	return rc;
 }
 
-int snp_send_guest_request(struct snp_msg_desc *mdesc, struct snp_guest_req *req,
-			   struct snp_guest_request_ioctl *rio)
+int snp_send_guest_request(struct snp_msg_desc *mdesc, struct snp_guest_req *req)
 {
 	u64 seqno;
 	int rc;
@@ -2043,14 +2040,14 @@ int snp_send_guest_request(struct snp_msg_desc *mdesc, struct snp_guest_req *req
 	req->input.resp_gpa = __pa(mdesc->response);
 	req->input.data_gpa = req->certs_data ? __pa(req->certs_data) : 0;
 
-	rc = __handle_guest_request(mdesc, req, rio);
+	rc = __handle_guest_request(mdesc, req);
 	if (rc) {
 		if (rc == -EIO &&
-		    rio->exitinfo2 == SNP_GUEST_VMM_ERR(SNP_GUEST_VMM_ERR_INVALID_LEN))
+		    req->exitinfo2 == SNP_GUEST_VMM_ERR(SNP_GUEST_VMM_ERR_INVALID_LEN))
 			return rc;
 
 		pr_alert("Detected error from ASP request. rc: %d, exitinfo2: 0x%llx\n",
-			 rc, rio->exitinfo2);
+			 rc, req->exitinfo2);
 
 		snp_disable_vmpck(mdesc);
 		return rc;
@@ -2069,7 +2066,6 @@ EXPORT_SYMBOL_GPL(snp_send_guest_request);
 
 static int __init snp_get_tsc_info(void)
 {
-	struct snp_guest_request_ioctl *rio;
 	struct snp_tsc_info_resp *tsc_resp;
 	struct snp_tsc_info_req *tsc_req;
 	struct snp_msg_desc *mdesc;
@@ -2093,13 +2089,9 @@ static int __init snp_get_tsc_info(void)
 	if (!req)
 		goto e_free_tsc_resp;
 
-	rio = kzalloc(sizeof(*rio), GFP_KERNEL);
-	if (!rio)
-		goto e_free_req;
-
 	mdesc = snp_msg_alloc();
 	if (IS_ERR_OR_NULL(mdesc))
-		goto e_free_rio;
+		goto e_free_req;
 
 	rc = snp_msg_init(mdesc, snp_vmpl);
 	if (rc)
@@ -2114,7 +2106,7 @@ static int __init snp_get_tsc_info(void)
 	req->resp_sz = sizeof(*tsc_resp) + AUTHTAG_LEN;
 	req->exit_code = SVM_VMGEXIT_GUEST_REQUEST;
 
-	rc = snp_send_guest_request(mdesc, req, rio);
+	rc = snp_send_guest_request(mdesc, req);
 	if (rc)
 		goto e_request;
 
@@ -2135,8 +2127,6 @@ e_request:
 	memzero_explicit(tsc_resp, sizeof(*tsc_resp) + AUTHTAG_LEN);
 e_free_mdesc:
 	snp_msg_free(mdesc);
-e_free_rio:
-	kfree(rio);
 e_free_req:
 	kfree(req);
  e_free_tsc_resp:
diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h
index 58e028d..fbb616f 100644
--- a/arch/x86/include/asm/sev.h
+++ b/arch/x86/include/asm/sev.h
@@ -231,6 +231,7 @@ struct snp_guest_req {
 	size_t resp_sz;
 
 	u64 exit_code;
+	u64 exitinfo2;
 	unsigned int vmpck_id;
 	u8 msg_version;
 	u8 msg_type;
@@ -486,8 +487,6 @@ static inline int pvalidate(unsigned long vaddr, bool rmp_psize, bool validate)
 	return rc;
 }
 
-struct snp_guest_request_ioctl;
-
 void setup_ghcb(void);
 void early_snp_set_memory_private(unsigned long vaddr, unsigned long paddr,
 				  unsigned long npages);
@@ -513,8 +512,7 @@ void snp_kexec_begin(void);
 int snp_msg_init(struct snp_msg_desc *mdesc, int vmpck_id);
 struct snp_msg_desc *snp_msg_alloc(void);
 void snp_msg_free(struct snp_msg_desc *mdesc);
-int snp_send_guest_request(struct snp_msg_desc *mdesc, struct snp_guest_req *req,
-			   struct snp_guest_request_ioctl *rio);
+int snp_send_guest_request(struct snp_msg_desc *mdesc, struct snp_guest_req *req);
 
 int snp_svsm_vtpm_send_command(u8 *buffer);
 
@@ -587,8 +585,8 @@ static inline void snp_kexec_begin(void) { }
 static inline int snp_msg_init(struct snp_msg_desc *mdesc, int vmpck_id) { return -1; }
 static inline struct snp_msg_desc *snp_msg_alloc(void) { return NULL; }
 static inline void snp_msg_free(struct snp_msg_desc *mdesc) { }
-static inline int snp_send_guest_request(struct snp_msg_desc *mdesc, struct snp_guest_req *req,
-					 struct snp_guest_request_ioctl *rio) { return -ENODEV; }
+static inline int snp_send_guest_request(struct snp_msg_desc *mdesc,
+					 struct snp_guest_req *req) { return -ENODEV; }
 static inline int snp_svsm_vtpm_send_command(u8 *buffer) { return -ENODEV; }
 static inline void __init snp_secure_tsc_prepare(void) { }
 static inline void __init snp_secure_tsc_init(void) { }
diff --git a/drivers/virt/coco/sev-guest/sev-guest.c b/drivers/virt/coco/sev-guest/sev-guest.c
index 7a4e218..d2b3ae7 100644
--- a/drivers/virt/coco/sev-guest/sev-guest.c
+++ b/drivers/virt/coco/sev-guest/sev-guest.c
@@ -101,7 +101,8 @@ static int get_report(struct snp_guest_dev *snp_dev, struct snp_guest_request_io
 	req.resp_sz = resp_len;
 	req.exit_code = SVM_VMGEXIT_GUEST_REQUEST;
 
-	rc = snp_send_guest_request(mdesc, &req, arg);
+	rc = snp_send_guest_request(mdesc, &req);
+	arg->exitinfo2 = req.exitinfo2;
 	if (rc)
 		goto e_free;
 
@@ -152,7 +153,8 @@ static int get_derived_key(struct snp_guest_dev *snp_dev, struct snp_guest_reque
 	req.resp_sz = resp_len;
 	req.exit_code = SVM_VMGEXIT_GUEST_REQUEST;
 
-	rc = snp_send_guest_request(mdesc, &req, arg);
+	rc = snp_send_guest_request(mdesc, &req);
+	arg->exitinfo2 = req.exitinfo2;
 	if (rc)
 		return rc;
 
@@ -249,7 +251,8 @@ cmd:
 	req.resp_sz = resp_len;
 	req.exit_code = SVM_VMGEXIT_EXT_GUEST_REQUEST;
 
-	ret = snp_send_guest_request(mdesc, &req, arg);
+	ret = snp_send_guest_request(mdesc, &req);
+	arg->exitinfo2 = req.exitinfo2;
 
 	/* If certs length is invalid then copy the returned length */
 	if (arg->vmm_error == SNP_GUEST_VMM_ERR_INVALID_LEN) {

[PATCH v2 2/4] x86/sev: Allocate request in TSC_INFO_REQ on stack

[Alexey Kardashevskiy]

Allocate a 88 byte request structure on stack and skip needless
kzalloc/kfree.

While at this, correct indent.

No functional change intended.

Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
Reviewed-by: Dionna Glaze <dionnaglaze@google.com>
Signed-off-by: Alexey Kardashevskiy <aik@amd.com>
---
 arch/x86/coco/sev/core.c | 30 ++++++++------------
 1 file changed, 12 insertions(+), 18 deletions(-)

diff --git a/arch/x86/coco/sev/core.c b/arch/x86/coco/sev/core.c
index cf91cb4e2c47..068653865bfb 100644
--- a/arch/x86/coco/sev/core.c
+++ b/arch/x86/coco/sev/core.c
@@ -2069,7 +2069,7 @@ static int __init snp_get_tsc_info(void)
 	struct snp_tsc_info_resp *tsc_resp;
 	struct snp_tsc_info_req *tsc_req;
 	struct snp_msg_desc *mdesc;
-	struct snp_guest_req *req;
+	struct snp_guest_req req = {};
 	int rc = -ENOMEM;
 
 	tsc_req = kzalloc(sizeof(*tsc_req), GFP_KERNEL);
@@ -2085,28 +2085,24 @@ static int __init snp_get_tsc_info(void)
 	if (!tsc_resp)
 		goto e_free_tsc_req;
 
-	req = kzalloc(sizeof(*req), GFP_KERNEL);
-	if (!req)
-		goto e_free_tsc_resp;
-
 	mdesc = snp_msg_alloc();
 	if (IS_ERR_OR_NULL(mdesc))
-		goto e_free_req;
+		goto e_free_tsc_resp;
 
 	rc = snp_msg_init(mdesc, snp_vmpl);
 	if (rc)
 		goto e_free_mdesc;
 
-	req->msg_version = MSG_HDR_VER;
-	req->msg_type = SNP_MSG_TSC_INFO_REQ;
-	req->vmpck_id = snp_vmpl;
-	req->req_buf = tsc_req;
-	req->req_sz = sizeof(*tsc_req);
-	req->resp_buf = (void *)tsc_resp;
-	req->resp_sz = sizeof(*tsc_resp) + AUTHTAG_LEN;
-	req->exit_code = SVM_VMGEXIT_GUEST_REQUEST;
+	req.msg_version = MSG_HDR_VER;
+	req.msg_type = SNP_MSG_TSC_INFO_REQ;
+	req.vmpck_id = snp_vmpl;
+	req.req_buf = tsc_req;
+	req.req_sz = sizeof(*tsc_req);
+	req.resp_buf = (void *)tsc_resp;
+	req.resp_sz = sizeof(*tsc_resp) + AUTHTAG_LEN;
+	req.exit_code = SVM_VMGEXIT_GUEST_REQUEST;
 
-	rc = snp_send_guest_request(mdesc, req);
+	rc = snp_send_guest_request(mdesc, &req);
 	if (rc)
 		goto e_request;
 
@@ -2127,9 +2123,7 @@ static int __init snp_get_tsc_info(void)
 	memzero_explicit(tsc_resp, sizeof(*tsc_resp) + AUTHTAG_LEN);
 e_free_mdesc:
 	snp_msg_free(mdesc);
-e_free_req:
-	kfree(req);
- e_free_tsc_resp:
+e_free_tsc_resp:
 	kfree(tsc_resp);
 e_free_tsc_req:
 	kfree(tsc_req);
-- 
2.49.0

[tip: x86/sev] x86/sev: Allocate request in TSC_INFO_REQ on stack

[tip-bot2 for Alexey Kardashevskiy]

The following commit has been merged into the x86/sev branch of tip:

Commit-ID:     d100016eac21636c8c0507a83bc32d9eb8cd56ab
Gitweb:        https://git.kernel.org/tip/d100016eac21636c8c0507a83bc32d9eb8cd56ab
Author:        Alexey Kardashevskiy <aik@amd.com>
AuthorDate:    Wed, 11 Jun 2025 14:08:40 +10:00
Committer:     Borislav Petkov (AMD) <bp@alien8.de>
CommitterDate: Wed, 18 Jun 2025 22:55:39 +02:00

x86/sev: Allocate request in TSC_INFO_REQ on stack

Allocate a 88 byte request structure on stack and skip needless
kzalloc/kfree.

While at this, correct indent.

No functional change intended.

Signed-off-by: Alexey Kardashevskiy <aik@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
Reviewed-by: Dionna Glaze <dionnaglaze@google.com>
Link: https://lore.kernel.org/20250611040842.2667262-3-aik@amd.com
---
 arch/x86/coco/sev/core.c | 30 ++++++++++++------------------
 1 file changed, 12 insertions(+), 18 deletions(-)

diff --git a/arch/x86/coco/sev/core.c b/arch/x86/coco/sev/core.c
index cf91cb4..0686538 100644
--- a/arch/x86/coco/sev/core.c
+++ b/arch/x86/coco/sev/core.c
@@ -2069,7 +2069,7 @@ static int __init snp_get_tsc_info(void)
 	struct snp_tsc_info_resp *tsc_resp;
 	struct snp_tsc_info_req *tsc_req;
 	struct snp_msg_desc *mdesc;
-	struct snp_guest_req *req;
+	struct snp_guest_req req = {};
 	int rc = -ENOMEM;
 
 	tsc_req = kzalloc(sizeof(*tsc_req), GFP_KERNEL);
@@ -2085,28 +2085,24 @@ static int __init snp_get_tsc_info(void)
 	if (!tsc_resp)
 		goto e_free_tsc_req;
 
-	req = kzalloc(sizeof(*req), GFP_KERNEL);
-	if (!req)
-		goto e_free_tsc_resp;
-
 	mdesc = snp_msg_alloc();
 	if (IS_ERR_OR_NULL(mdesc))
-		goto e_free_req;
+		goto e_free_tsc_resp;
 
 	rc = snp_msg_init(mdesc, snp_vmpl);
 	if (rc)
 		goto e_free_mdesc;
 
-	req->msg_version = MSG_HDR_VER;
-	req->msg_type = SNP_MSG_TSC_INFO_REQ;
-	req->vmpck_id = snp_vmpl;
-	req->req_buf = tsc_req;
-	req->req_sz = sizeof(*tsc_req);
-	req->resp_buf = (void *)tsc_resp;
-	req->resp_sz = sizeof(*tsc_resp) + AUTHTAG_LEN;
-	req->exit_code = SVM_VMGEXIT_GUEST_REQUEST;
+	req.msg_version = MSG_HDR_VER;
+	req.msg_type = SNP_MSG_TSC_INFO_REQ;
+	req.vmpck_id = snp_vmpl;
+	req.req_buf = tsc_req;
+	req.req_sz = sizeof(*tsc_req);
+	req.resp_buf = (void *)tsc_resp;
+	req.resp_sz = sizeof(*tsc_resp) + AUTHTAG_LEN;
+	req.exit_code = SVM_VMGEXIT_GUEST_REQUEST;
 
-	rc = snp_send_guest_request(mdesc, req);
+	rc = snp_send_guest_request(mdesc, &req);
 	if (rc)
 		goto e_request;
 
@@ -2127,9 +2123,7 @@ e_request:
 	memzero_explicit(tsc_resp, sizeof(*tsc_resp) + AUTHTAG_LEN);
 e_free_mdesc:
 	snp_msg_free(mdesc);
-e_free_req:
-	kfree(req);
- e_free_tsc_resp:
+e_free_tsc_resp:
 	kfree(tsc_resp);
 e_free_tsc_req:
 	kfree(tsc_req);

[PATCH v2 3/4] x86/sev: Document requirement for linear mapping of Guest Request buffers

[Alexey Kardashevskiy]

The Guest Request supports 3 types of messages now, the largest is
the extended variant of MSG_REPORT_REQ: sizeof(snp_ext_report_req)==112.
These used to be allocated on stack and then moved to the SNP guest
platform device (snp_guest_dev) for the reason explained in

commit db10cb9b5746 ("virt: sevguest: Fix passing a stack buffer as
a scatterlist target"):

aesgcm_encrypt() and aesgcm_decrypt() are used for guest messages and
might potentially use a crypto accelerator which requires DMA buffers
to be in the linear mapping.

Add a comment, pr_warn() and return -EINVAL when the buffers are not
in linear mapping.

Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
Reviewed-by: Dionna Glaze <dionnaglaze@google.com>
Signed-off-by: Alexey Kardashevskiy <aik@amd.com>
---
Changes:
v2:
* adjust grammar
---
 arch/x86/coco/sev/core.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/arch/x86/coco/sev/core.c b/arch/x86/coco/sev/core.c
index 068653865bfb..b0d423a353ab 100644
--- a/arch/x86/coco/sev/core.c
+++ b/arch/x86/coco/sev/core.c
@@ -2008,6 +2008,15 @@ int snp_send_guest_request(struct snp_msg_desc *mdesc, struct snp_guest_req *req
 	u64 seqno;
 	int rc;
 
+	/*
+	 * enc_payload() calls aesgcm_encrypt(), which can potentially offload to HW.
+	 * The offload's DMA SG list of data to encrypt has to be in linear mapping.
+	 */
+	if (!virt_addr_valid(req->req_buf) || !virt_addr_valid(req->resp_buf)) {
+		pr_warn("AES-GSM buffers must be in linear mapping");
+		return -EINVAL;
+	}
+
 	guard(mutex)(&snp_cmd_mutex);
 
 	/* Check if the VMPCK is not empty */
-- 
2.49.0

[tip: x86/sev] x86/sev: Document requirement for linear mapping of guest request buffers

[tip-bot2 for Alexey Kardashevskiy]

The following commit has been merged into the x86/sev branch of tip:

Commit-ID:     7ffeb2fc26707f613685ce7711c26a9de5890ab1
Gitweb:        https://git.kernel.org/tip/7ffeb2fc26707f613685ce7711c26a9de5890ab1
Author:        Alexey Kardashevskiy <aik@amd.com>
AuthorDate:    Wed, 11 Jun 2025 14:08:41 +10:00
Committer:     Borislav Petkov (AMD) <bp@alien8.de>
CommitterDate: Wed, 18 Jun 2025 22:55:53 +02:00

x86/sev: Document requirement for linear mapping of guest request buffers

The Guest Request supports 3 types of messages now, the largest is the
extended variant of MSG_REPORT_REQ: sizeof(snp_ext_report_req)==112.  These
used to be allocated on stack and then moved to the SNP guest platform device
(snp_guest_dev) for the reason explained in

  db10cb9b5746 ("virt: sevguest: Fix passing a stack buffer as a scatterlist target"):

aesgcm_encrypt() and aesgcm_decrypt() are used for guest messages and might
potentially use a crypto accelerator which requires DMA buffers to be in the
linear mapping.

Add a comment, warn and return an error when the buffers are not in linear
mapping.

Signed-off-by: Alexey Kardashevskiy <aik@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
Reviewed-by: Dionna Glaze <dionnaglaze@google.com>
Link: https://lore.kernel.org/20250611040842.2667262-4-aik@amd.com
---
 arch/x86/coco/sev/core.c |  9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/arch/x86/coco/sev/core.c b/arch/x86/coco/sev/core.c
index 0686538..b0d423a 100644
--- a/arch/x86/coco/sev/core.c
+++ b/arch/x86/coco/sev/core.c
@@ -2008,6 +2008,15 @@ int snp_send_guest_request(struct snp_msg_desc *mdesc, struct snp_guest_req *req
 	u64 seqno;
 	int rc;
 
+	/*
+	 * enc_payload() calls aesgcm_encrypt(), which can potentially offload to HW.
+	 * The offload's DMA SG list of data to encrypt has to be in linear mapping.
+	 */
+	if (!virt_addr_valid(req->req_buf) || !virt_addr_valid(req->resp_buf)) {
+		pr_warn("AES-GSM buffers must be in linear mapping");
+		return -EINVAL;
+	}
+
 	guard(mutex)(&snp_cmd_mutex);
 
 	/* Check if the VMPCK is not empty */

[PATCH v2 4/4] x86/sev: Drop unnecessary parameter in snp_issue_guest_request

[Alexey Kardashevskiy]

Commit 3e385c0d6ce8 ("virt: sev-guest: Move SNP Guest Request data
pages handling under snp_cmd_mutex")

moved @input from snp_msg_desc to snp_guest_req which is passed to
snp_issue_guest_request().

Drop the extra parameter.

No functional change intended.

Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
Reviewed-by: Dionna Glaze <dionnaglaze@google.com>
Signed-off-by: Alexey Kardashevskiy <aik@amd.com>
---
 arch/x86/coco/sev/core.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/x86/coco/sev/core.c b/arch/x86/coco/sev/core.c
index b0d423a353ab..8375ca7fbd8a 100644
--- a/arch/x86/coco/sev/core.c
+++ b/arch/x86/coco/sev/core.c
@@ -1389,8 +1389,9 @@ int snp_issue_svsm_attest_req(u64 call_id, struct svsm_call *call,
 }
 EXPORT_SYMBOL_GPL(snp_issue_svsm_attest_req);
 
-static int snp_issue_guest_request(struct snp_guest_req *req, struct snp_req_data *input)
+static int snp_issue_guest_request(struct snp_guest_req *req)
 {
+	struct snp_req_data *input = &req->input;
 	struct ghcb_state state;
 	struct es_em_ctxt ctxt;
 	unsigned long flags;
@@ -1932,7 +1933,7 @@ static int __handle_guest_request(struct snp_msg_desc *mdesc, struct snp_guest_r
 	 * sequence number must be incremented or the VMPCK must be deleted to
 	 * prevent reuse of the IV.
 	 */
-	rc = snp_issue_guest_request(req, &req->input);
+	rc = snp_issue_guest_request(req);
 	switch (rc) {
 	case -ENOSPC:
 		/*
-- 
2.49.0

[tip: x86/sev] x86/sev: Drop unnecessary parameter in snp_issue_guest_request()

[tip-bot2 for Alexey Kardashevskiy]

The following commit has been merged into the x86/sev branch of tip:

Commit-ID:     040ed574ee823a2ce5da36a8d385d3133787c9c5
Gitweb:        https://git.kernel.org/tip/040ed574ee823a2ce5da36a8d385d3133787c9c5
Author:        Alexey Kardashevskiy <aik@amd.com>
AuthorDate:    Wed, 11 Jun 2025 14:08:42 +10:00
Committer:     Borislav Petkov (AMD) <bp@alien8.de>
CommitterDate: Wed, 18 Jun 2025 22:55:58 +02:00

x86/sev: Drop unnecessary parameter in snp_issue_guest_request()

Commit

  3e385c0d6ce8 ("virt: sev-guest: Move SNP Guest Request data pages handling under snp_cmd_mutex")

moved @input from snp_msg_desc to snp_guest_req which is passed to
snp_issue_guest_request().

Drop the extra parameter.

No functional change intended.

Signed-off-by: Alexey Kardashevskiy <aik@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
Reviewed-by: Dionna Glaze <dionnaglaze@google.com>
Link: https://lore.kernel.org/20250611040842.2667262-5-aik@amd.com
---
 arch/x86/coco/sev/core.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/x86/coco/sev/core.c b/arch/x86/coco/sev/core.c
index b0d423a..8375ca7 100644
--- a/arch/x86/coco/sev/core.c
+++ b/arch/x86/coco/sev/core.c
@@ -1389,8 +1389,9 @@ int snp_issue_svsm_attest_req(u64 call_id, struct svsm_call *call,
 }
 EXPORT_SYMBOL_GPL(snp_issue_svsm_attest_req);
 
-static int snp_issue_guest_request(struct snp_guest_req *req, struct snp_req_data *input)
+static int snp_issue_guest_request(struct snp_guest_req *req)
 {
+	struct snp_req_data *input = &req->input;
 	struct ghcb_state state;
 	struct es_em_ctxt ctxt;
 	unsigned long flags;
@@ -1932,7 +1933,7 @@ retry_request:
 	 * sequence number must be incremented or the VMPCK must be deleted to
 	 * prevent reuse of the IV.
 	 */
-	rc = snp_issue_guest_request(req, &req->input);
+	rc = snp_issue_guest_request(req);
 	switch (rc) {
 	case -ENOSPC:
 		/*