[Intel-gfx] [PATCH v6 11/13] drm/i915/guc: Pre-allocate output nodes for extraction

Alan Previn
2022-02-26T05:53:37Z

In the rare but possible scenario where we are in the midst of
multiple GuC error-capture (and engine reset) events and the
user also triggers a forced full GT reset or the internal watchdog
triggers the same, intel_guc_submission_reset_prepare's call
to flush_work(&guc->ct.requests.worker) can cause the G2H message
handler to trigger intel_guc_capture_store_snapshot upon
receiving new G2H error-capture notifications. This can happen
despite the prior call to disable_submission(guc);. However,
there's no race-free way for intel_guc_capture_store_snapshot to
know that we are in the midst of a reset. That said, we can never
dynamically allocate the output nodes in this handler. Thus, we
shall pre-allocate a fixed number of empty nodes up front (at the
time of ADS registration) that we can consume from or return to
an internal cached list of nodes.

Signed-off-by: Alan Previn <alan.previn.teres.alexis@intel.com>
---
drivers/gpu/drm/i915/gt/uc/guc_capture_fwif.h | 19 +-
.../gpu/drm/i915/gt/uc/intel_guc_capture.c | 178 ++++++++++++++----
2 files changed, 160 insertions(+), 37 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/uc/guc_capture_fwif.h b/drivers/gpu/drm/i915/gt/uc/guc_capture_fwif.h
index 7c4f1e4ae0a5..b5eea9676668 100644
--- a/drivers/gpu/drm/i915/gt/uc/guc_capture_fwif.h
+++ b/drivers/gpu/drm/i915/gt/uc/guc_capture_fwif.h
@@ -30,7 +30,7 @@ struct __guc_capture_bufstate {
*
* A single unit of extracted error-capture output data grouped together
* at an engine-instance level. We keep these nodes in a linked list.
- * See outlist below.
+ * See cachelist and outlist below.
*/
struct __guc_capture_parsed_output {
/*
@@ -187,7 +187,22 @@ struct __guc_state_capture_priv {
[GUC_MAX_ENGINE_CLASSES];

/**
- * @outlist: allocated nodes with parsed engine-instance error capture data
+ * @cachelist: Pool of pre-allocated nodes for error capture output
+ *
+ * We need this pool of pre-allocated nodes because we cannot
+ * dynamically allocate new nodes when receiving the G2H notification
+ * because the event handlers for all G2H event-processing is called
+ * by the ct processing worker queue and when that queue is being
+ * processed, there is no absoluate guarantee that we are not in the
+ * midst of a GT reset operation (which doesn't allow allocations).
+ */
+ struct list_head cachelist;
+#define PREALLOC_NODES_MAX_COUNT (3 * GUC_MAX_ENGINE_CLASSES * GUC_MAX_INSTANCES_PER_CLASS)
+#define PREALLOC_NODES_DEFAULT_NUMREGS 64
+ int max_mmio_per_node;
+
+ /**
+ * @outlist: Pool of pre-allocated nodes for error capture output
*
* A linked list of parsed GuC error-capture output data before
* reporting with formatting via i915_gpu_coredump. Each node in this linked list shall
diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_capture.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_capture.c
index 492719137bd5..944b4bd8cdfb 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_guc_capture.c
+++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_capture.c
@@ -582,6 +582,8 @@ intel_guc_capture_getlistsize(struct intel_guc *guc, u32 owner, u32 type, u32 cl
return 0;
}

+static void guc_capture_create_prealloc_nodes(struct intel_guc *guc);
+
int
intel_guc_capture_getlist(struct intel_guc *guc, u32 owner, u32 type, u32 classid,
void **listptr)
@@ -601,6 +603,12 @@ intel_guc_capture_getlist(struct intel_guc *guc, u32 owner, u32 type, u32 classi
return cache->status;
}

+ /*
+ * ADS population of input registers is a good
+ * time to pre-allocate cachelist output nodes
+ */
+ guc_capture_create_prealloc_nodes(guc);
+
ret = intel_guc_capture_getlistsize(guc, owner, type, classid, &size);
if (ret) {
cache->list = NULL;
@@ -710,7 +718,8 @@ int intel_guc_capture_output_min_size_est(struct intel_guc *guc)
* err-state-captured register-list we find, we alloc 'C':
* --> alloc C: A capture-output-node structure that includes misc capture info along
* with 3 register list dumps (global, engine-class and engine-instance)
- * This node is dynamically allocated and populated with the error-capture
+ * This node is created from a pre-allocated list of blank nodes in
+ * guc->capture->priv->cachelist and populated with the error-capture
* data from GuC and then it's added into guc->capture->priv->outlist linked
* list. This list is used for matchup and printout by i915_gpu_coredump
* and err_print_gt, (when user invokes the error capture sysfs).
@@ -854,19 +863,20 @@ guc_capture_delete_one_node(struct intel_guc *guc, struct __guc_capture_parsed_o
}

static void
-guc_capture_delete_nodes(struct intel_guc *guc)
+guc_capture_delete_prealloc_nodes(struct intel_guc *guc)
{
+ struct __guc_capture_parsed_output *n, *ntmp;
+
/*
* NOTE: At the end of driver operation, we must assume that we
- * have nodes in outlist from unclaimed error capture events
- * that occurred prior to shutdown.
+ * have prealloc nodes in both the cachelist as well as outlist
+ * if unclaimed error capture events occurred prior to shutdown.
*/
- if (!list_empty(&guc->capture.priv->outlist)) {
- struct __guc_capture_parsed_output *n, *ntmp;
+ list_for_each_entry_safe(n, ntmp, &guc->capture.priv->outlist, link)
+ guc_capture_delete_one_node(guc, n);

- list_for_each_entry_safe(n, ntmp, &guc->capture.priv->outlist, link)
- guc_capture_delete_one_node(guc, n);
- }
+ list_for_each_entry_safe(n, ntmp, &guc->capture.priv->cachelist, link)
+ guc_capture_delete_one_node(guc, n);
}

static void
@@ -883,21 +893,80 @@ guc_capture_add_node_to_outlist(struct __guc_state_capture_priv *gc,
guc_capture_add_node_to_list(node, &gc->outlist);
}

+static void
+guc_capture_add_node_to_cachelist(struct __guc_state_capture_priv *gc,
+ struct __guc_capture_parsed_output *node)
+{
+ guc_capture_add_node_to_list(node, &gc->cachelist);
+}
+
static void
guc_capture_init_node(struct intel_guc *guc, struct __guc_capture_parsed_output *node)
{
+ struct guc_mmio_reg *tmp[GUC_CAPTURE_LIST_TYPE_MAX];
+ int i;
+
+ for (i = 0; i < GUC_CAPTURE_LIST_TYPE_MAX; ++i) {
+ tmp[i] = node->reginfo[i].regs;
+ memset(tmp[i], 0, sizeof(struct guc_mmio_reg) *
+ guc->capture.priv->max_mmio_per_node);
+ }
+ memset(node, 0, sizeof(*node));
+ for (i = 0; i < GUC_CAPTURE_LIST_TYPE_MAX; ++i)
+ node->reginfo[i].regs = tmp[i];
+
INIT_LIST_HEAD(&node->link);
}

+static struct __guc_capture_parsed_output *
+guc_capture_get_prealloc_node(struct intel_guc *guc)
+{
+ struct __guc_capture_parsed_output *found = NULL;
+
+ if (!list_empty(&guc->capture.priv->cachelist)) {
+ struct __guc_capture_parsed_output *n, *ntmp;
+
+ /* get first avail node from the cache list */
+ list_for_each_entry_safe(n, ntmp, &guc->capture.priv->cachelist, link) {
+ found = n;
+ list_del(&n->link);
+ break;
+ }
+ } else {
+ struct __guc_capture_parsed_output *n, *ntmp;
+
+ /* traverse down and steal back the oldest node already allocated */
+ list_for_each_entry_safe(n, ntmp, &guc->capture.priv->outlist, link) {
+ found = n;
+ }
+ if (found)
+ list_del(&found->link);
+ }
+ if (found)
+ guc_capture_init_node(guc, found);
+
+ return found;
+}
+
static struct __guc_capture_parsed_output *
guc_capture_alloc_one_node(struct intel_guc *guc)
{
struct __guc_capture_parsed_output *new;
+ int i;

new = kzalloc(sizeof(*new), GFP_KERNEL);
if (!new)
return NULL;

+ for (i = 0; i < GUC_CAPTURE_LIST_TYPE_MAX; ++i) {
+ new->reginfo[i].regs = kcalloc(guc->capture.priv->max_mmio_per_node,
+ sizeof(struct guc_mmio_reg), GFP_KERNEL);
+ if (!new->reginfo[i].regs) {
+ while (i)
+ kfree(new->reginfo[--i].regs);
+ return NULL;
+ }
+ }
guc_capture_init_node(guc, new);

return new;
@@ -910,7 +979,7 @@ guc_capture_clone_node(struct intel_guc *guc, struct __guc_capture_parsed_output
struct __guc_capture_parsed_output *new;
int i;

- new = guc_capture_alloc_one_node(guc);
+ new = guc_capture_get_prealloc_node(guc);
if (!new)
return NULL;
if (!ori)
@@ -921,16 +990,14 @@ guc_capture_clone_node(struct intel_guc *guc, struct __guc_capture_parsed_output
/* copy reg-lists that we want to clone */
for (i = 0; i < GUC_CAPTURE_LIST_TYPE_MAX; ++i) {
if (keep_reglist_mask & BIT(i)) {
- new->reginfo[i].regs = kcalloc(ori->reginfo[i].num_regs,
- sizeof(struct guc_mmio_reg), GFP_KERNEL);
- if (!new->reginfo[i].regs)
- goto bail_clone;
+ GEM_BUG_ON(ori->reginfo[i].num_regs >
+ guc->capture.priv->max_mmio_per_node);

memcpy(new->reginfo[i].regs, ori->reginfo[i].regs,
ori->reginfo[i].num_regs * sizeof(struct guc_mmio_reg));
+
new->reginfo[i].num_regs = ori->reginfo[i].num_regs;
new->reginfo[i].vfid = ori->reginfo[i].vfid;
-
if (i == GUC_CAPTURE_LIST_TYPE_ENGINE_CLASS) {
new->eng_class = ori->eng_class;
} else if (i == GUC_CAPTURE_LIST_TYPE_ENGINE_INSTANCE) {
@@ -942,14 +1009,58 @@ guc_capture_clone_node(struct intel_guc *guc, struct __guc_capture_parsed_output
}

return new;
+}

-bail_clone:
- for (i = 0; i < GUC_CAPTURE_LIST_TYPE_MAX; ++i) {
- if (new->reginfo[i].regs)
- kfree(new->reginfo[i].regs);
+static void
+__guc_capture_create_prealloc_nodes(struct intel_guc *guc)
+{
+ struct __guc_capture_parsed_output *node = NULL;
+ struct drm_i915_private *i915 = guc_to_gt(guc)->i915;
+ int i;
+
+ for (i = 0; i < PREALLOC_NODES_MAX_COUNT; ++i) {
+ node = guc_capture_alloc_one_node(guc);
+ if (!node) {
+ drm_warn(&i915->drm, "GuC Capture pre-alloc-cache failure\n");
+ /* dont free the priors, use what we got and cleanup at shutdown */
+ return;
+ }
+ guc_capture_add_node_to_cachelist(guc->capture.priv, node);
}
- kfree(new);
- return NULL;
+}
+
+static int
+guc_get_max_reglist_count(struct intel_guc *guc)
+{
+ int i, j, k, tmp, maxregcount = 0;
+
+ for (i = 0; i < GUC_CAPTURE_LIST_INDEX_MAX; ++i) {
+ for (j = 0; j < GUC_CAPTURE_LIST_TYPE_MAX; ++j) {
+ for (k = 0; k < GUC_MAX_ENGINE_CLASSES; ++k) {
+ if (j == GUC_CAPTURE_LIST_TYPE_GLOBAL && k > 0)
+ continue;
+
+ tmp = guc_cap_list_num_regs(guc->capture.priv, i, j, k);
+ if (tmp > maxregcount)
+ maxregcount = tmp;
+ }
+ }
+ }
+ if (!maxregcount)
+ maxregcount = PREALLOC_NODES_DEFAULT_NUMREGS;
+
+ return maxregcount;
+}
+
+static void
+guc_capture_create_prealloc_nodes(struct intel_guc *guc)
+{
+ /* skip if we've already done the pre-alloc */
+ if (guc->capture.priv->max_mmio_per_node)
+ return;
+
+ guc->capture.priv->max_mmio_per_node = guc_get_max_reglist_count(guc);
+ __guc_capture_create_prealloc_nodes(guc);
}

static int
@@ -1065,13 +1176,13 @@ guc_capture_extract_reglists(struct intel_guc *guc, struct __guc_capture_bufstat
guc_capture_add_node_to_outlist(guc->capture.priv, node);
node = NULL;
} else if (datatype == GUC_CAPTURE_LIST_TYPE_ENGINE_CLASS &&
- node->reginfo[GUC_CAPTURE_LIST_TYPE_ENGINE_CLASS].regs) {
+ node->reginfo[GUC_CAPTURE_LIST_TYPE_ENGINE_CLASS].num_regs) {
/* Add to list, clone node and duplicate global list */
guc_capture_add_node_to_outlist(guc->capture.priv, node);
node = guc_capture_clone_node(guc, node,
GCAP_PARSED_REGLIST_INDEX_GLOBAL);
} else if (datatype == GUC_CAPTURE_LIST_TYPE_ENGINE_INSTANCE &&
- node->reginfo[GUC_CAPTURE_LIST_TYPE_ENGINE_INSTANCE].regs) {
+ node->reginfo[GUC_CAPTURE_LIST_TYPE_ENGINE_INSTANCE].num_regs) {
/* Add to list, clone node and duplicate global + class lists */
guc_capture_add_node_to_outlist(guc->capture.priv, node);
node = guc_capture_clone_node(guc, node,
@@ -1081,7 +1192,7 @@ guc_capture_extract_reglists(struct intel_guc *guc, struct __guc_capture_bufstat
}

if (!node) {
- node = guc_capture_alloc_one_node(guc);
+ node = guc_capture_get_prealloc_node(guc);
if (!node) {
ret = -ENOMEM;
break;
@@ -1106,17 +1217,13 @@ guc_capture_extract_reglists(struct intel_guc *guc, struct __guc_capture_bufstat
break;
}

- regs = NULL;
numregs = FIELD_GET(CAP_HDR_NUM_MMIOS, hdr.num_mmios);
- if (numregs) {
- regs = kcalloc(numregs, sizeof(struct guc_mmio_reg), GFP_KERNEL);
- if (!regs) {
- ret = -ENOMEM;
- break;
- }
+ if (numregs > guc->capture.priv->max_mmio_per_node) {
+ drm_dbg(&i915->drm, "GuC Capture list extraction clipped by prealloc!\n");
+ numregs = guc->capture.priv->max_mmio_per_node;
}
node->reginfo[datatype].num_regs = numregs;
- node->reginfo[datatype].regs = regs;
+ regs = node->reginfo[datatype].regs;
i = 0;
while (numregs--) {
if (guc_capture_log_get_register(guc, buf, &regs[i++])) {
@@ -1136,8 +1243,8 @@ guc_capture_extract_reglists(struct intel_guc *guc, struct __guc_capture_bufstat
break;
}
}
- if (node) /* else free it */
- kfree(node);
+ if (node) /* else return it back to cache list */
+ guc_capture_add_node_to_cachelist(guc->capture.priv, node);
}
return ret;
}
@@ -1244,7 +1351,7 @@ void intel_guc_capture_destroy(struct intel_guc *guc)

guc_capture_free_ads_cache(guc->capture.priv);

- guc_capture_delete_nodes(guc);
+ guc_capture_delete_prealloc_nodes(guc);

if (guc->capture.priv->extlists) {
guc_capture_free_extlists(guc->capture.priv->extlists);
@@ -1264,6 +1371,7 @@ int intel_guc_capture_init(struct intel_guc *guc)
guc->capture.priv->reglists = guc_capture_get_device_reglist(guc);

INIT_LIST_HEAD(&guc->capture.priv->outlist);
+ INIT_LIST_HEAD(&guc->capture.priv->cachelist);

return 0;
}
--
2.25.1