From 2f3040584ae1734aad45e4c691f620e2bbdd3391 Mon Sep 17 00:00:00 2001
From: Matthew Auld <matthew.auld@intel.com>
Date: Mon, 18 Oct 2021 18:45:03 +0100
Subject: drm/i915/dmabuf: add paranoid flush-on-acquire
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Git-commit: a035154da45d19e09dc68454673ff257a660aece
Patch-mainline: v5.16-rc1
References: jsc#PED-1166 jsc#PED-1168 jsc#PED-1170 jsc#PED-1218 jsc#PED-1220 jsc#PED-1222 jsc#PED-1223 jsc#PED-1225
As pointed out by Thomas, we likely need to flush the pages here if the
GPU can read the page contents directly from main memory. Underneath we
don't know what the sg_table is pointing to, so just add a
wbinvd_on_all_cpus() here, for now.
Reported-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211018174508.2137279-4-matthew.auld@intel.com
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c b/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c
index 5be505ebbb7b..1adcd8e02d29 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c
@@ -232,6 +232,7 @@ struct dma_buf *i915_gem_prime_export(struct drm_gem_object *gem_obj, int flags)
static int i915_gem_object_get_pages_dmabuf(struct drm_i915_gem_object *obj)
{
+ struct drm_i915_private *i915 = to_i915(obj->base.dev);
struct sg_table *pages;
unsigned int sg_page_sizes;
@@ -242,8 +243,11 @@ static int i915_gem_object_get_pages_dmabuf(struct drm_i915_gem_object *obj)
if (IS_ERR(pages))
return PTR_ERR(pages);
- sg_page_sizes = i915_sg_dma_sizes(pages->sgl);
+ /* XXX: consider doing a vmap flush or something */
+ if (!HAS_LLC(i915) || i915_gem_object_can_bypass_llc(obj))
+ wbinvd_on_all_cpus();
+ sg_page_sizes = i915_sg_dma_sizes(pages->sgl);
__i915_gem_object_set_pages(obj, pages, sg_page_sizes);
return 0;
--
2.38.1