drm/xe: Invert page fault queue head / tail

Convention for queues in Linux is the producer moves the head and
consumer moves the tail. Fix the page fault queue to conform to this
convention.

Cc: Lucas De Marchi <lucas.demarchi@intel.com>
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>

diff --git a/drivers/gpu/drm/xe/xe_gt_pagefault.c b/drivers/gpu/drm/xe/xe_gt_pagefault.c
index 0a61e4413679ecc07bcef1ac57123318c5562a6a..3ca715e2ec19eca247f10e6b9f2e885404e97db1 100644 (file)
--- a/drivers/gpu/drm/xe/xe_gt_pagefault.c
+++ b/drivers/gpu/drm/xe/xe_gt_pagefault.c
@@ -282,9 +282,9 @@ static bool get_pagefault(struct pf_queue *pf_queue, struct pagefault *pf)
        bool ret = false;
 
        spin_lock_irq(&pf_queue->lock);
-       if (pf_queue->head != pf_queue->tail) {
+       if (pf_queue->tail != pf_queue->head) {
                desc = (const struct xe_guc_pagefault_desc *)
-                       (pf_queue->data + pf_queue->head);
+                       (pf_queue->data + pf_queue->tail);
 
                pf->fault_level = FIELD_GET(PFD_FAULT_LEVEL, desc->dw0);
                pf->trva_fault = FIELD_GET(XE2_PFD_TRVA_FAULT, desc->dw0);
@@ -302,7 +302,7 @@ static bool get_pagefault(struct pf_queue *pf_queue, struct pagefault *pf)
                pf->page_addr |= FIELD_GET(PFD_VIRTUAL_ADDR_LO, desc->dw2) <<
                        PFD_VIRTUAL_ADDR_LO_SHIFT;
 
-               pf_queue->head = (pf_queue->head + PF_MSG_LEN_DW) %
+               pf_queue->tail = (pf_queue->tail + PF_MSG_LEN_DW) %
                        PF_QUEUE_NUM_DW;
                ret = true;
        }
@@ -315,7 +315,7 @@ static bool pf_queue_full(struct pf_queue *pf_queue)
 {
        lockdep_assert_held(&pf_queue->lock);
 
-       return CIRC_SPACE(pf_queue->tail, pf_queue->head, PF_QUEUE_NUM_DW) <=
+       return CIRC_SPACE(pf_queue->head, pf_queue->tail, PF_QUEUE_NUM_DW) <=
                PF_MSG_LEN_DW;
 }
 
@@ -342,8 +342,8 @@ int xe_guc_pagefault_handler(struct xe_guc *guc, u32 *msg, u32 len)
        spin_lock_irqsave(&pf_queue->lock, flags);
        full = pf_queue_full(pf_queue);
        if (!full) {
-               memcpy(pf_queue->data + pf_queue->tail, msg, len * sizeof(u32));
-               pf_queue->tail = (pf_queue->tail + len) % PF_QUEUE_NUM_DW;
+               memcpy(pf_queue->data + pf_queue->head, msg, len * sizeof(u32));
+               pf_queue->head = (pf_queue->head + len) % PF_QUEUE_NUM_DW;
                queue_work(gt->usm.pf_wq, &pf_queue->worker);
        } else {
                drm_warn(&xe->drm, "PF Queue full, shouldn't be possible");
@@ -389,7 +389,7 @@ static void pf_queue_work_func(struct work_struct *w)
                send_pagefault_reply(&gt->uc.guc, &reply);
 
                if (time_after(jiffies, threshold) &&
-                   pf_queue->head != pf_queue->tail) {
+                   pf_queue->tail != pf_queue->head) {
                        queue_work(gt->usm.pf_wq, w);
                        break;
                }

diff --git a/drivers/gpu/drm/xe/xe_gt_types.h b/drivers/gpu/drm/xe/xe_gt_types.h
index f746846604759335147e482b442cf6833547b6e2..b15503dabba4b4888d4138035fec6c8f70079530 100644 (file)
--- a/drivers/gpu/drm/xe/xe_gt_types.h
+++ b/drivers/gpu/drm/xe/xe_gt_types.h
@@ -225,16 +225,16 @@ struct xe_gt {
 #define PF_QUEUE_NUM_DW        128
                        /** @data: data in the page fault queue */
                        u32 data[PF_QUEUE_NUM_DW];
-                       /**
-                        * @head: head pointer in DWs for page fault queue,
-                        * moved by worker which processes faults.
-                        */
-                       u16 head;
                        /**
                         * @tail: tail pointer in DWs for page fault queue,
-                        * moved by G2H handler.
+                        * moved by worker which processes faults (consumer).
                         */
                        u16 tail;
+                       /**
+                        * @head: head pointer in DWs for page fault queue,
+                        * moved by G2H handler (producer).
+                        */
+                       u16 head;
                        /** @lock: protects page fault queue */
                        spinlock_t lock;
                        /** @worker: to process page faults */