[RFC PATCH 19/97] drm/i915/guc: Always copy CT message to new allocation
Matthew Brost
matthew.brost at intel.com
Tue May 25 18:25:06 UTC 2021
On Thu, May 06, 2021 at 12:13:33PM -0700, Matthew Brost wrote:
> From: Michal Wajdeczko <michal.wajdeczko at intel.com>
>
> Since most of future CT traffic will be based on G2H requests,
> instead of copying incoming CT message to static buffer and then
> create new allocation for such request, always copy incoming CT
> message to new allocation. Also by doing it while reading CT
> header, we can safely fallback if that atomic allocation fails.
>
> Signed-off-by: Michal Wajdeczko <michal.wajdeczko at intel.com>
> Signed-off-by: Matthew Brost <matthew.brost at intel.com>
> Cc: Piotr Piórkowski <piotr.piorkowski at intel.com>
Reviewed-by: Matthew Brost <matthew.brost at intel.com>
> ---
> drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c | 180 ++++++++++++++--------
> 1 file changed, 120 insertions(+), 60 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c
> index d630ec32decf..a174978c6a27 100644
> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c
> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c
> @@ -72,8 +72,9 @@ struct ct_request {
> u32 *response_buf;
> };
>
> -struct ct_incoming_request {
> +struct ct_incoming_msg {
> struct list_head link;
> + u32 size;
> u32 msg[];
> };
>
> @@ -575,7 +576,26 @@ static inline bool ct_header_is_response(u32 header)
> return !!(header & GUC_CT_MSG_IS_RESPONSE);
> }
>
> -static int ct_read(struct intel_guc_ct *ct, u32 *data)
> +static struct ct_incoming_msg *ct_alloc_msg(u32 num_dwords)
> +{
> + struct ct_incoming_msg *msg;
> +
> + msg = kmalloc(sizeof(*msg) + sizeof(u32) * num_dwords, GFP_ATOMIC);
> + if (msg)
> + msg->size = num_dwords;
> + return msg;
> +}
> +
> +static void ct_free_msg(struct ct_incoming_msg *msg)
> +{
> + kfree(msg);
> +}
> +
> +/*
> + * Return: number available remaining dwords to read (0 if empty)
> + * or a negative error code on failure
> + */
> +static int ct_read(struct intel_guc_ct *ct, struct ct_incoming_msg **msg)
> {
> struct intel_guc_ct_buffer *ctb = &ct->ctbs.recv;
> struct guc_ct_buffer_desc *desc = ctb->desc;
> @@ -586,6 +606,7 @@ static int ct_read(struct intel_guc_ct *ct, u32 *data)
> s32 available;
> unsigned int len;
> unsigned int i;
> + u32 header;
>
> if (unlikely(desc->is_in_error))
> return -EPIPE;
> @@ -601,8 +622,10 @@ static int ct_read(struct intel_guc_ct *ct, u32 *data)
>
> /* tail == head condition indicates empty */
> available = tail - head;
> - if (unlikely(available == 0))
> - return -ENODATA;
> + if (unlikely(available == 0)) {
> + *msg = NULL;
> + return 0;
> + }
>
> /* beware of buffer wrap case */
> if (unlikely(available < 0))
> @@ -610,14 +633,14 @@ static int ct_read(struct intel_guc_ct *ct, u32 *data)
> CT_DEBUG(ct, "available %d (%u:%u)\n", available, head, tail);
> GEM_BUG_ON(available < 0);
>
> - data[0] = cmds[head];
> + header = cmds[head];
> head = (head + 1) % size;
>
> /* message len with header */
> - len = ct_header_get_len(data[0]) + 1;
> + len = ct_header_get_len(header) + 1;
> if (unlikely(len > (u32)available)) {
> CT_ERROR(ct, "Incomplete message %*ph %*ph %*ph\n",
> - 4, data,
> + 4, &header,
> 4 * (head + available - 1 > size ?
> size - head : available - 1), &cmds[head],
> 4 * (head + available - 1 > size ?
> @@ -625,11 +648,24 @@ static int ct_read(struct intel_guc_ct *ct, u32 *data)
> goto corrupted;
> }
>
> + *msg = ct_alloc_msg(len);
> + if (!*msg) {
> + CT_ERROR(ct, "No memory for message %*ph %*ph %*ph\n",
> + 4, &header,
> + 4 * (head + available - 1 > size ?
> + size - head : available - 1), &cmds[head],
> + 4 * (head + available - 1 > size ?
> + available - 1 - size + head : 0), &cmds[0]);
> + return available;
> + }
> +
> + (*msg)->msg[0] = header;
> +
> for (i = 1; i < len; i++) {
> - data[i] = cmds[head];
> + (*msg)->msg[i] = cmds[head];
> head = (head + 1) % size;
> }
> - CT_DEBUG(ct, "received %*ph\n", 4 * len, data);
> + CT_DEBUG(ct, "received %*ph\n", 4 * len, (*msg)->msg);
>
> desc->head = head * 4;
> return available - len;
> @@ -659,33 +695,33 @@ static int ct_read(struct intel_guc_ct *ct, u32 *data)
> * ^-----------------------len-----------------------^
> */
>
> -static int ct_handle_response(struct intel_guc_ct *ct, const u32 *msg)
> +static int ct_handle_response(struct intel_guc_ct *ct, struct ct_incoming_msg *response)
> {
> - u32 header = msg[0];
> + u32 header = response->msg[0];
> u32 len = ct_header_get_len(header);
> - u32 msgsize = (len + 1) * sizeof(u32); /* msg size in bytes w/header */
> u32 fence;
> u32 status;
> u32 datalen;
> struct ct_request *req;
> unsigned long flags;
> bool found = false;
> + int err = 0;
>
> GEM_BUG_ON(!ct_header_is_response(header));
>
> /* Response payload shall at least include fence and status */
> if (unlikely(len < 2)) {
> - CT_ERROR(ct, "Corrupted response %*ph\n", msgsize, msg);
> + CT_ERROR(ct, "Corrupted response (len %u)\n", len);
> return -EPROTO;
> }
>
> - fence = msg[1];
> - status = msg[2];
> + fence = response->msg[1];
> + status = response->msg[2];
> datalen = len - 2;
>
> /* Format of the status follows RESPONSE message */
> if (unlikely(!INTEL_GUC_MSG_IS_RESPONSE(status))) {
> - CT_ERROR(ct, "Corrupted response %*ph\n", msgsize, msg);
> + CT_ERROR(ct, "Corrupted response (status %#x)\n", status);
> return -EPROTO;
> }
>
> @@ -699,12 +735,13 @@ static int ct_handle_response(struct intel_guc_ct *ct, const u32 *msg)
> continue;
> }
> if (unlikely(datalen > req->response_len)) {
> - CT_ERROR(ct, "Response for %u is too long %*ph\n",
> - req->fence, msgsize, msg);
> - datalen = 0;
> + CT_ERROR(ct, "Response %u too long (datalen %u > %u)\n",
> + req->fence, datalen, req->response_len);
> + datalen = min(datalen, req->response_len);
> + err = -EMSGSIZE;
> }
> if (datalen)
> - memcpy(req->response_buf, msg + 3, 4 * datalen);
> + memcpy(req->response_buf, response->msg + 3, 4 * datalen);
> req->response_len = datalen;
> WRITE_ONCE(req->status, status);
> found = true;
> @@ -712,45 +749,61 @@ static int ct_handle_response(struct intel_guc_ct *ct, const u32 *msg)
> }
> spin_unlock_irqrestore(&ct->requests.lock, flags);
>
> - if (!found)
> - CT_ERROR(ct, "Unsolicited response %*ph\n", msgsize, msg);
> + if (!found) {
> + CT_ERROR(ct, "Unsolicited response (fence %u)\n", fence);
> + return -ENOKEY;
> + }
> +
> + if (unlikely(err))
> + return err;
> +
> + ct_free_msg(response);
> return 0;
> }
>
> -static void ct_process_request(struct intel_guc_ct *ct,
> - u32 action, u32 len, const u32 *payload)
> +static int ct_process_request(struct intel_guc_ct *ct, struct ct_incoming_msg *request)
> {
> struct intel_guc *guc = ct_to_guc(ct);
> + u32 header, action, len;
> + const u32 *payload;
> int ret;
>
> + header = request->msg[0];
> + payload = &request->msg[1];
> + action = ct_header_get_action(header);
> + len = ct_header_get_len(header);
> +
> CT_DEBUG(ct, "request %x %*ph\n", action, 4 * len, payload);
>
> switch (action) {
> case INTEL_GUC_ACTION_DEFAULT:
> ret = intel_guc_to_host_process_recv_msg(guc, payload, len);
> - if (unlikely(ret))
> - goto fail_unexpected;
> break;
> -
> default:
> -fail_unexpected:
> - CT_ERROR(ct, "Unexpected request %x %*ph\n",
> - action, 4 * len, payload);
> + ret = -EOPNOTSUPP;
> break;
> }
> +
> + if (unlikely(ret)) {
> + CT_ERROR(ct, "Failed to process request %04x (%pe)\n",
> + action, ERR_PTR(ret));
> + return ret;
> + }
> +
> + ct_free_msg(request);
> + return 0;
> }
>
> static bool ct_process_incoming_requests(struct intel_guc_ct *ct)
> {
> unsigned long flags;
> - struct ct_incoming_request *request;
> - u32 header;
> - u32 *payload;
> + struct ct_incoming_msg *request;
> bool done;
> + int err;
>
> spin_lock_irqsave(&ct->requests.lock, flags);
> request = list_first_entry_or_null(&ct->requests.incoming,
> - struct ct_incoming_request, link);
> + struct ct_incoming_msg, link);
> if (request)
> list_del(&request->link);
> done = !!list_empty(&ct->requests.incoming);
> @@ -759,14 +812,13 @@ static bool ct_process_incoming_requests(struct intel_guc_ct *ct)
> if (!request)
> return true;
>
> - header = request->msg[0];
> - payload = &request->msg[1];
> - ct_process_request(ct,
> - ct_header_get_action(header),
> - ct_header_get_len(header),
> - payload);
> + err = ct_process_request(ct, request);
> + if (unlikely(err)) {
> + CT_ERROR(ct, "Failed to process CT message (%pe) %*ph\n",
> + ERR_PTR(err), 4 * request->size, request->msg);
> + ct_free_msg(request);
> + }
>
> - kfree(request);
> return done;
> }
>
> @@ -799,22 +851,11 @@ static void ct_incoming_request_worker_func(struct work_struct *w)
> * ^-----------------------len-----------------------^
> */
>
> -static int ct_handle_request(struct intel_guc_ct *ct, const u32 *msg)
> +static int ct_handle_request(struct intel_guc_ct *ct, struct ct_incoming_msg *request)
> {
> - u32 header = msg[0];
> - u32 len = ct_header_get_len(header);
> - u32 msgsize = (len + 1) * sizeof(u32); /* msg size in bytes w/header */
> - struct ct_incoming_request *request;
> unsigned long flags;
>
> - GEM_BUG_ON(ct_header_is_response(header));
> -
> - request = kmalloc(sizeof(*request) + msgsize, GFP_ATOMIC);
> - if (unlikely(!request)) {
> - CT_ERROR(ct, "Dropping request %*ph\n", msgsize, msg);
> - return 0; /* XXX: -ENOMEM ? */
> - }
> - memcpy(request->msg, msg, msgsize);
> + GEM_BUG_ON(ct_header_is_response(request->msg[0]));
>
> spin_lock_irqsave(&ct->requests.lock, flags);
> list_add_tail(&request->link, &ct->requests.incoming);
> @@ -824,22 +865,41 @@ static int ct_handle_request(struct intel_guc_ct *ct, const u32 *msg)
> return 0;
> }
>
> +static void ct_handle_msg(struct intel_guc_ct *ct, struct ct_incoming_msg *msg)
> +{
> + u32 header = msg->msg[0];
> + int err;
> +
> + if (ct_header_is_response(header))
> + err = ct_handle_response(ct, msg);
> + else
> + err = ct_handle_request(ct, msg);
> +
> + if (unlikely(err)) {
> + CT_ERROR(ct, "Failed to process CT message (%pe) %*ph\n",
> + ERR_PTR(err), 4 * msg->size, msg->msg);
> + ct_free_msg(msg);
> + }
> +}
> +
> +/*
> + * Return: number available remaining dwords to read (0 if empty)
> + * or a negative error code on failure
> + */
> static int ct_receive(struct intel_guc_ct *ct)
> {
> - u32 msg[GUC_CT_MSG_LEN_MASK + 1]; /* one extra dw for the header */
> + struct ct_incoming_msg *msg = NULL;
> unsigned long flags;
> int ret;
>
> spin_lock_irqsave(&ct->ctbs.recv.lock, flags);
> - ret = ct_read(ct, msg);
> + ret = ct_read(ct, &msg);
> spin_unlock_irqrestore(&ct->ctbs.recv.lock, flags);
> if (ret < 0)
> return ret;
>
> - if (ct_header_is_response(msg[0]))
> - ct_handle_response(ct, msg);
> - else
> - ct_handle_request(ct, msg);
> + if (msg)
> + ct_handle_msg(ct, msg);
>
> return ret;
> }
> --
> 2.28.0
>
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