-----Original Message----- From: Chris Wilson chris@chris-wilson.co.uk Sent: Tuesday, December 15, 2020 12:31 PM To: intel-gfx@lists.freedesktop.org Cc: Chris Wilson chris@chris-wilson.co.uk; Tang, CQ cq.tang@intel.com; stable@vger.kernel.org Subject: [PATCH] drm/i915: Fix mismatch between misplaced vma check and vma insert
When inserting a VMA, we restrict the placement to the low 4G unless the caller opts into using the full range. This was done to allow usersapce the opportunity to transition slowly from a 32b address space, and to avoid breaking inherent 32b assumptions of some commands.
However, for insert we limited ourselves to 4G-4K, but on verification we allowed the full 4G. This causes some attempts to bind a new buffer to sporadically fail with -ENOSPC, but at other times be bound successfully.
commit 48ea1e32c39d ("drm/i915/gen9: Set PIN_ZONE_4G end to 4GB - 1 page") suggests that there is a genuine problem with stateless addressing that cannot utilize the last page in 4G and so we purposefully excluded it.
Reported-by: CQ Tang cq.tang@intel.com Fixes: 48ea1e32c39d ("drm/i915/gen9: Set PIN_ZONE_4G end to 4GB - 1 page") Signed-off-by: Chris Wilson chris@chris-wilson.co.uk Cc: CQ Tang cq.tang@intel.com Cc: stable@vger.kernel.org
drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c index 193996144c84..2ff32daa50bd 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c +++ b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c @@ -382,7 +382,7 @@ eb_vma_misplaced(const struct drm_i915_gem_exec_object2 *entry, return true;
if (!(flags & EXEC_OBJECT_SUPPORTS_48B_ADDRESS) &&
(vma->node.start + vma->node.size - 1) >> 32)
(vma->node.start + vma->node.size + 4095) >> 32)
Why 4095 not 4096?
--CQ
return true;if (flags & __EXEC_OBJECT_NEEDS_MAP &&
2.20.1