Commit c7fac450 authored by Alan Previn's avatar Alan Previn Committed by Rodrigo Vivi
Browse files

drm/xe/guc: Fix h2g_write usage of GUC_CTB_MSG_MAX_LEN 



In the ABI header, GUC_CTB_MSG_MIN_LEN is '1' because
GUC_CTB_HDR_LEN is 1. This aligns with H2G/G2H CTB specification
where all command formats are defined in units of dwords so that '1'
is a dword. Accordingly, GUC_CTB_MSG_MAX_LEN is 256-1 (i.e. 255
dwords). However, h2g_write was incorrectly assuming that
GUC_CTB_MSG_MAX_LEN was in bytes. Fix this.

v3: Fix nit on #define location.(Matt)
v2: By correctly treating GUC_CTB_MSG_MAX_LEN as dwords, it causes
    a local array to consume 4x the stack size. Rework the function
    to avoid consuming stack even if the action size is large. (Matt)

Signed-off-by: default avatarAlan Previn <alan.previn.teres.alexis@intel.com>
Reviewed-by: default avatarMatthew Brost <matthew.brost@intel.com>
Signed-off-by: default avatarRodrigo Vivi <rodrigo.vivi@intel.com>
parent 44869c72

drivers/gpu/drm/xe/xe_guc_ct.c

+19 −13
Original line number Diff line number Diff line
@@ -396,24 +396,27 @@ static void g2h_release_space(struct xe_guc_ct *ct, u32 g2h_len) 
	spin_unlock_irq(&ct->fast_lock);

}



#define H2G_CT_HEADERS (GUC_CTB_HDR_LEN + 1) /* one DW CTB header and one DW HxG header */



static int h2g_write(struct xe_guc_ct *ct, const u32 *action, u32 len,

		     u32 ct_fence_value, bool want_response)

{

	struct xe_device *xe = ct_to_xe(ct);

	struct guc_ctb *h2g = &ct->ctbs.h2g;

	u32 cmd[GUC_CTB_MSG_MAX_LEN / sizeof(u32)];

	u32 cmd_len = len + GUC_CTB_HDR_LEN;

	u32 cmd_idx = 0, i;

	u32 cmd[H2G_CT_HEADERS];

	u32 tail = h2g->info.tail;

	u32 full_len;

	struct iosys_map map = IOSYS_MAP_INIT_OFFSET(&h2g->cmds,

							 tail * sizeof(u32));



	full_len = len + GUC_CTB_HDR_LEN;



	lockdep_assert_held(&ct->lock);

	XE_BUG_ON(len * sizeof(u32) > GUC_CTB_MSG_MAX_LEN);

	XE_BUG_ON(full_len > (GUC_CTB_MSG_MAX_LEN - GUC_CTB_HDR_LEN));

	XE_BUG_ON(tail > h2g->info.size);



	/* Command will wrap, zero fill (NOPs), return and check credits again */

	if (tail + cmd_len > h2g->info.size) {

	if (tail + full_len > h2g->info.size) {

		xe_map_memset(xe, &map, 0, 0,

			      (h2g->info.size - tail) * sizeof(u32));

		h2g_reserve_space(ct, (h2g->info.size - tail));
@@ -428,30 +431,33 @@ static int h2g_write(struct xe_guc_ct *ct, const u32 *action, u32 len, 
	 * dw1: HXG header (including action code)

	 * dw2+: action data

	 */

	cmd[cmd_idx++] = FIELD_PREP(GUC_CTB_MSG_0_FORMAT, GUC_CTB_FORMAT_HXG) |

	cmd[0] = FIELD_PREP(GUC_CTB_MSG_0_FORMAT, GUC_CTB_FORMAT_HXG) |

		FIELD_PREP(GUC_CTB_MSG_0_NUM_DWORDS, len) |

		FIELD_PREP(GUC_CTB_MSG_0_FENCE, ct_fence_value);

	if (want_response) {

		cmd[cmd_idx++] =

		cmd[1] =

			FIELD_PREP(GUC_HXG_MSG_0_TYPE, GUC_HXG_TYPE_REQUEST) |

			FIELD_PREP(GUC_HXG_EVENT_MSG_0_ACTION |

				   GUC_HXG_EVENT_MSG_0_DATA0, action[0]);

	} else {

		cmd[cmd_idx++] =

		cmd[1] =

			FIELD_PREP(GUC_HXG_MSG_0_TYPE, GUC_HXG_TYPE_EVENT) |

			FIELD_PREP(GUC_HXG_EVENT_MSG_0_ACTION |

				   GUC_HXG_EVENT_MSG_0_DATA0, action[0]);

	}

	for (i = 1; i < len; ++i)

		cmd[cmd_idx++] = action[i];



	/* H2G header in cmd[1] replaces action[0] so: */

	--len;

	++action;



	/* Write H2G ensuring visable before descriptor update */

	xe_map_memcpy_to(xe, &map, 0, cmd, cmd_len * sizeof(u32));

	xe_map_memcpy_to(xe, &map, 0, cmd, H2G_CT_HEADERS * sizeof(u32));

	xe_map_memcpy_to(xe, &map, H2G_CT_HEADERS * sizeof(u32), action, len * sizeof(u32));

	xe_device_wmb(ct_to_xe(ct));



	/* Update local copies */

	h2g->info.tail = (tail + cmd_len) % h2g->info.size;

	h2g_reserve_space(ct, cmd_len);

	h2g->info.tail = (tail + full_len) % h2g->info.size;

	h2g_reserve_space(ct, full_len);



	/* Update descriptor */

	desc_write(xe, h2g, tail, h2g->info.tail);