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Date: Mon, 3 Apr 2023 14:59:00 -0500
From: Tom Lendacky <thomas.lendacky@....com>
To: Nikunj A Dadhania <nikunj@....com>, linux-kernel@...r.kernel.org,
x86@...nel.org
Cc: bp@...en8.de, dionnaglaze@...gle.com, pgonda@...gle.com,
seanjc@...gle.com, pbonzini@...hat.com, michael.roth@....com,
ketanch@...k.ac.in
Subject: Re: [PATCH v2 03/11] virt: sev-guest: Add snp_guest_req structure
On 3/26/23 09:46, Nikunj A Dadhania wrote:
> 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.
>
> Signed-off-by: Nikunj A Dadhania <nikunj@....com>
> ---
> drivers/virt/coco/sev-guest/sev-guest.c | 87 ++++++++++++++-----------
> drivers/virt/coco/sev-guest/sev-guest.h | 19 ++++++
> 2 files changed, 68 insertions(+), 38 deletions(-)
>
> diff --git a/drivers/virt/coco/sev-guest/sev-guest.c b/drivers/virt/coco/sev-guest/sev-guest.c
> index 6ae197b57644..ec93dee330f2 100644
> --- a/drivers/virt/coco/sev-guest/sev-guest.c
> +++ b/drivers/virt/coco/sev-guest/sev-guest.c
> @@ -60,16 +60,6 @@ static inline unsigned int get_ctx_authsize(struct snp_guest_dev *snp_dev)
> return 0;
> }
>
> -static bool is_vmpck_empty(struct snp_guest_dev *snp_dev)
> -{
> - char zero_key[VMPCK_KEY_LEN] = {0};
> -
> - if (snp_dev->vmpck)
> - return !memcmp(snp_dev->vmpck, zero_key, VMPCK_KEY_LEN);
> -
> - return true;
> -}
> -
This change seems separate from the changes for snp_guest_req.
> /*
> * If an error is received from the host or AMD Secure Processor (ASP) there
> * are two options. Either retry the exact same encrypted request or discontinue
> @@ -198,8 +188,9 @@ static int verify_and_dec_payload(struct snp_guest_dev *snp_dev, void *payload,
> struct snp_guest_msg_hdr *resp_hdr = &resp->hdr;
> struct aesgcm_ctx *ctx = snp_dev->ctx;
>
> - dev_dbg(snp_dev->dev, "response [seqno %lld type %d version %d sz %d]\n",
> - resp_hdr->msg_seqno, resp_hdr->msg_type, resp_hdr->msg_version, resp_hdr->msg_sz);
> + pr_debug("response [seqno %lld type %d version %d sz %d]\n",
> + resp_hdr->msg_seqno, resp_hdr->msg_type, resp_hdr->msg_version,
> + resp_hdr->msg_sz);
Again, not related to the purpose of this patch.
>
> /* Verify that the sequence counter is incremented by 1 */
> if (unlikely(resp_hdr->msg_seqno != (req_hdr->msg_seqno + 1)))
> @@ -221,34 +212,34 @@ static int verify_and_dec_payload(struct snp_guest_dev *snp_dev, void *payload,
> return dec_payload(ctx, resp, payload, resp_hdr->msg_sz);
> }
>
> -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, u8 __vmpck_id)
Can the vmpck_id be part of the snp_guest_req structure?
> {
> - struct snp_guest_msg *req = snp_dev->request;
> - struct snp_guest_msg_hdr *hdr = &req->hdr;
> + struct snp_guest_msg *msg = snp_dev->request;
> + struct snp_guest_msg_hdr *hdr = &msg->hdr;
>
> - 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 = __vmpck_id;
> + hdr->msg_sz = req->req_sz;
>
> /* Verify the sequence number is non-zero */
> if (!hdr->msg_seqno)
> return -ENOSR;
>
> - dev_dbg(snp_dev->dev, "request [seqno %lld type %d version %d sz %d]\n",
> + pr_debug("request [seqno %lld type %d version %d sz %d]\n",
Unrelated change.
> hdr->msg_seqno, hdr->msg_type, hdr->msg_version, hdr->msg_sz);
>
> - return __enc_payload(snp_dev->ctx, req, payload, sz);
> + return __enc_payload(snp_dev->ctx, msg, req->req_buf, req->req_sz);
> }
>
> -static int __handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code, __u64 *fw_err)
> +static int __handle_guest_request(struct snp_guest_dev *snp_dev, struct snp_guest_req *req)
> {
> unsigned long err = 0xff, override_err = 0;
> unsigned long req_start = jiffies;
> @@ -262,7 +253,7 @@ 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, &err);
> + rc = snp_issue_guest_request(req->exit_code, &snp_dev->input, &err);
> switch (rc) {
> case -ENOSPC:
> /*
> @@ -273,7 +264,7 @@ static int __handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code,
> * IV reuse.
> */
> override_npages = snp_dev->input.data_npages;
> - exit_code = SVM_VMGEXIT_GUEST_REQUEST;
> + req->exit_code = SVM_VMGEXIT_GUEST_REQUEST;
>
> /*
> * Override the error to inform callers the given extended
> @@ -314,8 +305,8 @@ static int __handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code,
> */
> snp_inc_msg_seqno(snp_dev);
>
> - if (fw_err)
> - *fw_err = override_err ?: err;
> + if (req->fw_err)
> + *req->fw_err = override_err ?: err;
>
> if (override_npages)
> snp_dev->input.data_npages = override_npages;
> @@ -332,13 +323,14 @@ static int __handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code,
> return rc;
> }
>
> -static int handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code, int msg_ver,
> - u8 type, void *req_buf, size_t req_sz, void *resp_buf,
> - u32 resp_sz, __u64 *fw_err)
> +static int snp_send_guest_request(struct snp_guest_dev *snp_dev, struct snp_guest_req *req)
> {
> u64 seqno;
> int rc;
>
> + if (!snp_dev || !req)
> + return -ENODEV;
This seems unrelated, at least the check for snp_dev. And looking at the
only caller, a guest request is always provided. So this seems unnecessary
- at least at this point in the series.
> +
> /* Get message sequence and verify that its a non-zero */
> seqno = snp_get_msg_seqno(snp_dev);
> if (!seqno)
> @@ -347,21 +339,22 @@ static int handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code, in
> memset(snp_dev->response, 0, sizeof(struct snp_guest_msg));
>
> /* Encrypt the userspace provided payload */
> - rc = enc_payload(snp_dev, seqno, msg_ver, type, req_buf, req_sz);
> + rc = enc_payload(snp_dev, seqno, req, vmpck_id);
> if (rc)
> return rc;
>
> - rc = __handle_guest_request(snp_dev, exit_code, fw_err);
> + rc = __handle_guest_request(snp_dev, req);
> if (rc) {
> - if (rc == -EIO && *fw_err == SNP_GUEST_REQ_INVALID_LEN)
> + if (rc == -EIO && *req->fw_err == SNP_GUEST_REQ_INVALID_LEN)
> return rc;
>
> - dev_alert(snp_dev->dev, "Detected error from ASP request. rc: %d, fw_err: %llu\n", rc, *fw_err);
> + dev_alert(snp_dev->dev, "Detected error from ASP request. rc: %d, fw_err: %llu\n",
> + rc, *req->fw_err);
> 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->resp_buf, req->resp_sz);
Can't you just pass req here?
> if (rc) {
> dev_alert(snp_dev->dev, "Detected unexpected decode failure from ASP. rc: %d\n", rc);
> snp_disable_vmpck(snp_dev);
> @@ -371,6 +364,24 @@ static int handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code, in
> return 0;
> }
>
> +
> +static int handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code, u8 msg_version,
> + u8 msg_type, void *req_buf, size_t req_sz, void *resp_buf,
> + u32 resp_sz, __u64 *fw_err)
> +{
> + struct snp_guest_req guest_req = {
> + .msg_version = msg_version,
> + .msg_type = msg_type,
> + .req_buf = req_buf,
> + .req_sz = req_sz,
> + .resp_buf = resp_buf,
> + .resp_sz = resp_sz,
> + .fw_err = fw_err,
> + .exit_code = exit_code,
> + };
Add a blank line here.
Thanks,
Tom
> + return snp_send_guest_request(snp_dev, &guest_req);
> +}
> +
> static int get_report(struct snp_guest_dev *snp_dev, struct snp_guest_request_ioctl *arg)
> {
> struct snp_report_resp *resp;
> @@ -544,7 +555,7 @@ static long snp_guest_ioctl(struct file *file, unsigned int ioctl, unsigned long
> mutex_lock(&snp_dev->cmd_mutex);
>
> /* Check if the VMPCK is not empty */
> - if (is_vmpck_empty(snp_dev)) {
> + if (is_vmpck_empty(snp_dev->vmpck)) {
> dev_err_ratelimited(snp_dev->dev, "VMPCK is disabled\n");
> mutex_unlock(&snp_dev->cmd_mutex);
> return -ENOTTY;
> @@ -678,7 +689,7 @@ static int __init sev_guest_probe(struct platform_device *pdev)
> }
>
> /* Verify that VMPCK is not zero. */
> - if (is_vmpck_empty(snp_dev)) {
> + if (is_vmpck_empty(snp_dev->vmpck)) {
> dev_err(dev, "vmpck id %d is null\n", vmpck_id);
> goto e_unmap;
> }
> diff --git a/drivers/virt/coco/sev-guest/sev-guest.h b/drivers/virt/coco/sev-guest/sev-guest.h
> index ceb798a404d6..d245578d988e 100644
> --- a/drivers/virt/coco/sev-guest/sev-guest.h
> +++ b/drivers/virt/coco/sev-guest/sev-guest.h
> @@ -63,4 +63,23 @@ struct snp_guest_msg {
> u8 payload[4000];
> } __packed;
>
> +struct snp_guest_req {
> + void *req_buf, *resp_buf;
> + size_t req_sz, resp_sz;
> + u64 exit_code;
> + u64 *fw_err;
> + u8 msg_version;
> + u8 msg_type;
> +};
> +
> +static inline bool is_vmpck_empty(u8 *vmpck)
> +{
> + char zero_key[VMPCK_KEY_LEN] = {0};
> +
> + if (vmpck)
> + return !memcmp(vmpck, zero_key, VMPCK_KEY_LEN);
> +
> + return true;
> +}
> +
> #endif /* __VIRT_SEVGUEST_H__ */
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