[PATCH v6 04/16] virt: sev-guest: Add SNP guest request structure

From: Nikunj A Dadhania
Date: Tue Nov 28 2023 - 08:01:35 EST

Add a snp_guest_req structure to simplify the function arguments. The
structure will be used to call the SNP Guest message request API
instead of passing a long list of parameters.

Update snp_issue_guest_request() prototype to include the new guest request
structure and move the prototype to sev_guest.h.

Signed-off-by: Nikunj A Dadhania <nikunj@xxxxxxx>
---
.../x86/include/asm}/sev-guest.h | 18 +++
arch/x86/include/asm/sev.h | 8 --
arch/x86/kernel/sev.c | 15 ++-
drivers/virt/coco/sev-guest/sev-guest.c | 108 +++++++++++-------
4 files changed, 93 insertions(+), 56 deletions(-)
rename {drivers/virt/coco/sev-guest => arch/x86/include/asm}/sev-guest.h (78%)

diff --git a/drivers/virt/coco/sev-guest/sev-guest.h b/arch/x86/include/asm/sev-guest.h
similarity index 78%
rename from drivers/virt/coco/sev-guest/sev-guest.h
rename to arch/x86/include/asm/sev-guest.h
index ceb798a404d6..27cc15ad6131 100644
--- a/drivers/virt/coco/sev-guest/sev-guest.h
+++ b/arch/x86/include/asm/sev-guest.h
@@ -63,4 +63,22 @@ struct snp_guest_msg {
u8 payload[4000];
} __packed;

+struct snp_guest_req {
+ void *req_buf;
+ size_t req_sz;
+
+ void *resp_buf;
+ size_t resp_sz;
+
+ void *data;
+ size_t data_npages;
+
+ u64 exit_code;
+ unsigned int vmpck_id;
+ u8 msg_version;
+ u8 msg_type;
+};
+
+int snp_issue_guest_request(struct snp_guest_req *req, struct snp_req_data *input,
+ struct snp_guest_request_ioctl *rio);
#endif /* __VIRT_SEVGUEST_H__ */
diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h
index 5b4a1ce3d368..78465a8c7dc6 100644
--- a/arch/x86/include/asm/sev.h
+++ b/arch/x86/include/asm/sev.h
@@ -97,8 +97,6 @@ extern bool handle_vc_boot_ghcb(struct pt_regs *regs);
struct snp_req_data {
unsigned long req_gpa;
unsigned long resp_gpa;
- unsigned long data_gpa;
- unsigned int data_npages;
};

struct sev_guest_platform_data {
@@ -209,7 +207,6 @@ void snp_set_memory_private(unsigned long vaddr, unsigned long npages);
void snp_set_wakeup_secondary_cpu(void);
bool snp_init(struct boot_params *bp);
void __init __noreturn snp_abort(void);
-int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, struct snp_guest_request_ioctl *rio);
void snp_accept_memory(phys_addr_t start, phys_addr_t end);
u64 snp_get_unsupported_features(u64 status);
u64 sev_get_status(void);
@@ -233,11 +230,6 @@ static inline void snp_set_memory_private(unsigned long vaddr, unsigned long npa
static inline void snp_set_wakeup_secondary_cpu(void) { }
static inline bool snp_init(struct boot_params *bp) { return false; }
static inline void snp_abort(void) { }
-static inline int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, struct snp_guest_request_ioctl *rio)
-{
- return -ENOTTY;
-}
-
static inline void snp_accept_memory(phys_addr_t start, phys_addr_t end) { }
static inline u64 snp_get_unsupported_features(u64 status) { return 0; }
static inline u64 sev_get_status(void) { return 0; }
diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c
index 70472eebe719..01a400681529 100644
--- a/arch/x86/kernel/sev.c
+++ b/arch/x86/kernel/sev.c
@@ -28,6 +28,7 @@
#include <asm/cpu_entry_area.h>
#include <asm/stacktrace.h>
#include <asm/sev.h>
+#include <asm/sev-guest.h>
#include <asm/insn-eval.h>
#include <asm/fpu/xcr.h>
#include <asm/processor.h>
@@ -2167,15 +2168,21 @@ static int __init init_sev_config(char *str)
}
__setup("sev=", init_sev_config);

-int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, struct snp_guest_request_ioctl *rio)
+int snp_issue_guest_request(struct snp_guest_req *req, struct snp_req_data *input,
+ struct snp_guest_request_ioctl *rio)
{
struct ghcb_state state;
struct es_em_ctxt ctxt;
unsigned long flags;
struct ghcb *ghcb;
+ u64 exit_code;
int ret;

rio->exitinfo2 = SEV_RET_NO_FW_CALL;
+ if (!req)
+ return -EINVAL;
+
+ exit_code = req->exit_code;

/*
* __sev_get_ghcb() needs to run with IRQs disabled because it is using
@@ -2192,8 +2199,8 @@ int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, struct sn
vc_ghcb_invalidate(ghcb);

if (exit_code == SVM_VMGEXIT_EXT_GUEST_REQUEST) {
- ghcb_set_rax(ghcb, input->data_gpa);
- ghcb_set_rbx(ghcb, input->data_npages);
+ ghcb_set_rax(ghcb, __pa(req->data));
+ ghcb_set_rbx(ghcb, req->data_npages);
}

ret = sev_es_ghcb_hv_call(ghcb, &ctxt, exit_code, input->req_gpa, input->resp_gpa);
@@ -2212,7 +2219,7 @@ int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, struct sn
case SNP_GUEST_VMM_ERR(SNP_GUEST_VMM_ERR_INVALID_LEN):
/* Number of expected pages are returned in RBX */
if (exit_code == SVM_VMGEXIT_EXT_GUEST_REQUEST) {
- input->data_npages = ghcb_get_rbx(ghcb);
+ req->data_npages = ghcb_get_rbx(ghcb);
ret = -ENOSPC;
break;
}
diff --git a/drivers/virt/coco/sev-guest/sev-guest.c b/drivers/virt/coco/sev-guest/sev-guest.c
index 917c19e9e5ed..1579140d43ec 100644
--- a/drivers/virt/coco/sev-guest/sev-guest.c
+++ b/drivers/virt/coco/sev-guest/sev-guest.c
@@ -27,8 +27,7 @@

#include <asm/svm.h>
#include <asm/sev.h>
-
-#include "sev-guest.h"
+#include <asm/sev-guest.h>

#define DEVICE_NAME "sev-guest"

@@ -169,7 +168,7 @@ static struct aesgcm_ctx *snp_init_crypto(u8 *key, size_t keylen)
return ctx;
}

-static int verify_and_dec_payload(struct snp_guest_dev *snp_dev, void *payload, u32 sz)
+static int verify_and_dec_payload(struct snp_guest_dev *snp_dev, struct snp_guest_req *guest_req)
{
struct snp_guest_msg *resp = &snp_dev->secret_response;
struct snp_guest_msg *req = &snp_dev->secret_request;
@@ -198,36 +197,35 @@ static int verify_and_dec_payload(struct snp_guest_dev *snp_dev, void *payload,
* If the message size is greater than our buffer length then return
* an error.
*/
- if (unlikely((resp_hdr->msg_sz + ctx->authsize) > sz))
+ if (unlikely((resp_hdr->msg_sz + ctx->authsize) > guest_req->resp_sz))
return -EBADMSG;

/* Decrypt the payload */
memcpy(iv, &resp_hdr->msg_seqno, sizeof(resp_hdr->msg_seqno));
- if (!aesgcm_decrypt(ctx, payload, resp->payload, resp_hdr->msg_sz,
+ if (!aesgcm_decrypt(ctx, guest_req->resp_buf, resp->payload, resp_hdr->msg_sz,
&resp_hdr->algo, AAD_LEN, iv, resp_hdr->authtag))
return -EBADMSG;

return 0;
}

-static int enc_payload(struct snp_guest_dev *snp_dev, u64 seqno, int version, u8 type,
- void *payload, size_t sz)
+static int enc_payload(struct snp_guest_dev *snp_dev, u64 seqno, struct snp_guest_req *req)
{
- struct snp_guest_msg *req = &snp_dev->secret_request;
- struct snp_guest_msg_hdr *hdr = &req->hdr;
+ struct snp_guest_msg *msg = &snp_dev->secret_request;
+ struct snp_guest_msg_hdr *hdr = &msg->hdr;
struct aesgcm_ctx *ctx = snp_dev->ctx;
u8 iv[GCM_AES_IV_SIZE] = {};

- memset(req, 0, sizeof(*req));
+ memset(msg, 0, sizeof(*msg));

hdr->algo = SNP_AEAD_AES_256_GCM;
hdr->hdr_version = MSG_HDR_VER;
hdr->hdr_sz = sizeof(*hdr);
- hdr->msg_type = type;
- hdr->msg_version = version;
+ hdr->msg_type = req->msg_type;
+ hdr->msg_version = req->msg_version;
hdr->msg_seqno = seqno;
- hdr->msg_vmpck = vmpck_id;
- hdr->msg_sz = sz;
+ hdr->msg_vmpck = req->vmpck_id;
+ hdr->msg_sz = req->req_sz;

/* Verify the sequence number is non-zero */
if (!hdr->msg_seqno)
@@ -236,17 +234,17 @@ static int enc_payload(struct snp_guest_dev *snp_dev, u64 seqno, int version, u8
pr_debug("request [seqno %lld type %d version %d sz %d]\n",
hdr->msg_seqno, hdr->msg_type, hdr->msg_version, hdr->msg_sz);

- if (WARN_ON((sz + ctx->authsize) > sizeof(req->payload)))
+ if (WARN_ON((req->req_sz + ctx->authsize) > sizeof(msg->payload)))
return -EBADMSG;

memcpy(iv, &hdr->msg_seqno, sizeof(hdr->msg_seqno));
- aesgcm_encrypt(ctx, req->payload, payload, sz, &hdr->algo, AAD_LEN,
- iv, hdr->authtag);
+ aesgcm_encrypt(ctx, msg->payload, req->req_buf, req->req_sz, &hdr->algo,
+ AAD_LEN, iv, hdr->authtag);

return 0;
}

-static int __handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code,
+static int __handle_guest_request(struct snp_guest_dev *snp_dev, struct snp_guest_req *req,
struct snp_guest_request_ioctl *rio)
{
unsigned long req_start = jiffies;
@@ -261,7 +259,7 @@ static int __handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code,
* sequence number must be incremented or the VMPCK must be deleted to
* prevent reuse of the IV.
*/
- rc = snp_issue_guest_request(exit_code, &snp_dev->input, rio);
+ rc = snp_issue_guest_request(req, &snp_dev->input, rio);
switch (rc) {
case -ENOSPC:
/*
@@ -271,8 +269,8 @@ static int __handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code,
* order to increment the sequence number and thus avoid
* IV reuse.
*/
- override_npages = snp_dev->input.data_npages;
- exit_code = SVM_VMGEXIT_GUEST_REQUEST;
+ override_npages = req->data_npages;
+ req->exit_code = SVM_VMGEXIT_GUEST_REQUEST;

/*
* Override the error to inform callers the given extended
@@ -327,15 +325,13 @@ static int __handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code,
}

if (override_npages)
- snp_dev->input.data_npages = override_npages;
+ req->data_npages = override_npages;

return rc;
}

-static int handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code,
- struct snp_guest_request_ioctl *rio, u8 type,
- void *req_buf, size_t req_sz, void *resp_buf,
- u32 resp_sz)
+static int snp_send_guest_request(struct snp_guest_dev *snp_dev, struct snp_guest_req *req,
+ struct snp_guest_request_ioctl *rio)
{
u64 seqno;
int rc;
@@ -349,7 +345,7 @@ static int handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code,
memset(snp_dev->response, 0, sizeof(struct snp_guest_msg));

/* Encrypt the userspace provided payload in snp_dev->secret_request. */
- rc = enc_payload(snp_dev, seqno, rio->msg_version, type, req_buf, req_sz);
+ rc = enc_payload(snp_dev, seqno, req);
if (rc)
return rc;

@@ -360,7 +356,7 @@ static int handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code,
memcpy(snp_dev->request, &snp_dev->secret_request,
sizeof(snp_dev->secret_request));

- rc = __handle_guest_request(snp_dev, exit_code, rio);
+ rc = __handle_guest_request(snp_dev, req, rio);
if (rc) {
if (rc == -EIO &&
rio->exitinfo2 == SNP_GUEST_VMM_ERR(SNP_GUEST_VMM_ERR_INVALID_LEN))
@@ -369,12 +365,11 @@ static int handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code,
dev_alert(snp_dev->dev,
"Detected error from ASP request. rc: %d, exitinfo2: 0x%llx\n",
rc, rio->exitinfo2);
-
snp_disable_vmpck(snp_dev);
return rc;
}

- rc = verify_and_dec_payload(snp_dev, resp_buf, resp_sz);
+ rc = verify_and_dec_payload(snp_dev, req);
if (rc) {
dev_alert(snp_dev->dev, "Detected unexpected decode failure from ASP. rc: %d\n", rc);
snp_disable_vmpck(snp_dev);
@@ -392,6 +387,7 @@ struct snp_req_resp {
static int get_report(struct snp_guest_dev *snp_dev, struct snp_guest_request_ioctl *arg)
{
struct snp_report_req *req = &snp_dev->req.report;
+ struct snp_guest_req guest_req = {0};
struct snp_report_resp *resp;
int rc, resp_len;

@@ -413,9 +409,16 @@ static int get_report(struct snp_guest_dev *snp_dev, struct snp_guest_request_io
if (!resp)
return -ENOMEM;

- rc = handle_guest_request(snp_dev, SVM_VMGEXIT_GUEST_REQUEST, arg,
- SNP_MSG_REPORT_REQ, req, sizeof(*req), resp->data,
- resp_len);
+ guest_req.msg_version = arg->msg_version;
+ guest_req.msg_type = SNP_MSG_REPORT_REQ;
+ guest_req.vmpck_id = vmpck_id;
+ guest_req.req_buf = req;
+ guest_req.req_sz = sizeof(*req);
+ guest_req.resp_buf = resp->data;
+ guest_req.resp_sz = resp_len;
+ guest_req.exit_code = SVM_VMGEXIT_GUEST_REQUEST;
+
+ rc = snp_send_guest_request(snp_dev, &guest_req, arg);
if (rc)
goto e_free;

@@ -431,6 +434,7 @@ static int get_derived_key(struct snp_guest_dev *snp_dev, struct snp_guest_reque
{
struct snp_derived_key_req *req = &snp_dev->req.derived_key;
struct snp_derived_key_resp resp = {0};
+ struct snp_guest_req guest_req = {0};
int rc, resp_len;
/* Response data is 64 bytes and max authsize for GCM is 16 bytes. */
u8 buf[64 + 16];
@@ -452,8 +456,16 @@ static int get_derived_key(struct snp_guest_dev *snp_dev, struct snp_guest_reque
if (copy_from_user(req, (void __user *)arg->req_data, sizeof(*req)))
return -EFAULT;

- rc = handle_guest_request(snp_dev, SVM_VMGEXIT_GUEST_REQUEST, arg,
- SNP_MSG_KEY_REQ, req, sizeof(*req), buf, resp_len);
+ guest_req.msg_version = arg->msg_version;
+ guest_req.msg_type = SNP_MSG_KEY_REQ;
+ guest_req.vmpck_id = vmpck_id;
+ guest_req.req_buf = req;
+ guest_req.req_sz = sizeof(*req);
+ guest_req.resp_buf = buf;
+ guest_req.resp_sz = resp_len;
+ guest_req.exit_code = SVM_VMGEXIT_GUEST_REQUEST;
+
+ rc = snp_send_guest_request(snp_dev, &guest_req, arg);
if (rc)
return rc;

@@ -472,9 +484,10 @@ static int get_ext_report(struct snp_guest_dev *snp_dev, struct snp_guest_reques

{
struct snp_ext_report_req *req = &snp_dev->req.ext_report;
+ struct snp_guest_req guest_req = {0};
struct snp_report_resp *resp;
- int ret, npages = 0, resp_len;
sockptr_t certs_address;
+ int ret, resp_len;

lockdep_assert_held(&snp_dev->cmd_mutex);

@@ -507,7 +520,7 @@ static int get_ext_report(struct snp_guest_dev *snp_dev, struct snp_guest_reques
* zeros to indicate that certificate data was not provided.
*/
memset(snp_dev->certs_data, 0, req->certs_len);
- npages = req->certs_len >> PAGE_SHIFT;
+ guest_req.data_npages = req->certs_len >> PAGE_SHIFT;
cmd:
/*
* The intermediate response buffer is used while decrypting the
@@ -519,14 +532,21 @@ static int get_ext_report(struct snp_guest_dev *snp_dev, struct snp_guest_reques
if (!resp)
return -ENOMEM;

- snp_dev->input.data_npages = npages;
- ret = handle_guest_request(snp_dev, SVM_VMGEXIT_EXT_GUEST_REQUEST, arg,
- SNP_MSG_REPORT_REQ, &req->data,
- sizeof(req->data), resp->data, resp_len);
+ guest_req.msg_version = arg->msg_version;
+ guest_req.msg_type = SNP_MSG_REPORT_REQ;
+ guest_req.vmpck_id = vmpck_id;
+ guest_req.req_buf = &req->data;
+ guest_req.req_sz = sizeof(req->data);
+ guest_req.resp_buf = resp->data;
+ guest_req.resp_sz = resp_len;
+ guest_req.exit_code = SVM_VMGEXIT_EXT_GUEST_REQUEST;
+ guest_req.data = snp_dev->certs_data;
+
+ ret = snp_send_guest_request(snp_dev, &guest_req, arg);

/* If certs length is invalid then copy the returned length */
if (arg->vmm_error == SNP_GUEST_VMM_ERR_INVALID_LEN) {
- req->certs_len = snp_dev->input.data_npages << PAGE_SHIFT;
+ req->certs_len = guest_req.data_npages << PAGE_SHIFT;

if (copy_to_sockptr(io->req_data, req, sizeof(*req)))
ret = -EFAULT;
@@ -535,7 +555,8 @@ static int get_ext_report(struct snp_guest_dev *snp_dev, struct snp_guest_reques
if (ret)
goto e_free;

- if (npages && copy_to_sockptr(certs_address, snp_dev->certs_data, req->certs_len)) {
+ if (guest_req.data_npages && req->certs_len &&
+ copy_to_sockptr(certs_address, snp_dev->certs_data, req->certs_len)) {
ret = -EFAULT;
goto e_free;
}
@@ -869,7 +890,6 @@ static int __init sev_guest_probe(struct platform_device *pdev)
/* initial the input address for guest request */
snp_dev->input.req_gpa = __pa(snp_dev->request);
snp_dev->input.resp_gpa = __pa(snp_dev->response);
- snp_dev->input.data_gpa = __pa(snp_dev->certs_data);

ret = tsm_register(&sev_tsm_ops, snp_dev, &tsm_report_extra_type);
if (ret)
--
2.34.1