[Intel-gfx] [PATCH] drm/i915/gem: Support parsing of oversize batches

[Chris Wilson]

Matthew Auld noted that on more recent systems (such as the parser for
gen9) we may have objects that are larger than expected by the GEM uAPI
(i.e. greater than u32). These objects would have incorrect implicit batch
lengths, causing the parser to reject them for being incomplete.

Based on a patch by Matthew Auld.

Reported-by: Matthew Auld <matthew.auld at intel.com
Fixes: 435e8fc059db ("drm/i915: Allow parsing of unsized batches")
Testcase: igt/gem_exec_params/larger-than-life-batch
Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Matthew Auld <matthew.auld at intel.com
Cc: Mika Kuoppala <mika.kuoppala at linux.intel.com>
Cc: Jon Bloomfield <jon.bloomfield at intel.com>
---
 drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
index 4b09bcd70cf4..44b4558d5e86 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
@@ -287,8 +287,8 @@ struct i915_execbuffer {
 	u64 invalid_flags; /** Set of execobj.flags that are invalid */
 	u32 context_flags; /** Set of execobj.flags to insert from the ctx */
 
+	u64 batch_len; /** Length of batch within object */
 	u32 batch_start_offset; /** Location within object of batch */
-	u32 batch_len; /** Length of batch within object */
 	u32 batch_flags; /** Flags composed for emit_bb_start() */
 	struct intel_gt_buffer_pool_node *batch_pool; /** pool node for batch buffer */
 
@@ -871,6 +871,10 @@ static int eb_lookup_vmas(struct i915_execbuffer *eb)
 
 	if (eb->batch_len == 0)
 		eb->batch_len = eb->batch->vma->size - eb->batch_start_offset;
+	if (eb->batch_len == 0) {
+		drm_dbg(&i915->drm, "Invalid batch length\n");
+		return -EINVAL;
+	}
 
 	return 0;
 
@@ -2424,7 +2428,7 @@ static int eb_parse(struct i915_execbuffer *eb)
 	struct drm_i915_private *i915 = eb->i915;
 	struct intel_gt_buffer_pool_node *pool = eb->batch_pool;
 	struct i915_vma *shadow, *trampoline, *batch;
-	unsigned int len;
+	unsigned long len = eb->batch_len;
 	int err;
 
 	if (!eb_use_cmdparser(eb)) {
@@ -2435,7 +2439,6 @@ static int eb_parse(struct i915_execbuffer *eb)
 		goto secure_batch;
 	}
 
-	len = eb->batch_len;
 	if (!CMDPARSER_USES_GGTT(eb->i915)) {
 		/*
 		 * ppGTT backed shadow buffers must be mapped RO, to prevent
@@ -2449,6 +2452,8 @@ static int eb_parse(struct i915_execbuffer *eb)
 	} else {
 		len += I915_CMD_PARSER_TRAMPOLINE_SIZE;
 	}
+	if (len < eb->batch_len)
+		return -EINVAL;
 
 	if (!pool) {
 		pool = intel_gt_get_buffer_pool(eb->engine->gt, len);
-- 
2.20.1