drm/i915: mark requests for GuC virtual engines to avoid use-after-free

From Andrzej Hajda
8017a27cec32eac8c8f9430b0a3055840136b856 in linux-6.1.y/6.1.54
5eefc5307c983b59344a4cb89009819f580c84fa in mainline linux

diff --git a/sys/dev/pci/drm/i915/gt/intel_engine_types.h b/sys/dev/pci/drm/i915/gt/intel_engine_types.h
index 0e1f997..8b93cdc 100644 (file)
--- a/sys/dev/pci/drm/i915/gt/intel_engine_types.h
+++ b/sys/dev/pci/drm/i915/gt/intel_engine_types.h
@@ -56,6 +56,7 @@ struct intel_breadcrumbs;
 
 typedef u32 intel_engine_mask_t;
 #define ALL_ENGINES ((intel_engine_mask_t)~0ul)
+#define VIRTUAL_ENGINES BIT(BITS_PER_TYPE(intel_engine_mask_t) - 1)
 
 struct intel_hw_status_page {
        struct list_head timelines;

diff --git a/sys/dev/pci/drm/i915/gt/uc/intel_guc_submission.c b/sys/dev/pci/drm/i915/gt/uc/intel_guc_submission.c
index 3a811a6..5eab9d4 100644 (file)
--- a/sys/dev/pci/drm/i915/gt/uc/intel_guc_submission.c
+++ b/sys/dev/pci/drm/i915/gt/uc/intel_guc_submission.c
@@ -5121,6 +5121,11 @@ guc_create_virtual(struct intel_engine_cs **siblings, unsigned int count,
 
        ve->base.flags = I915_ENGINE_IS_VIRTUAL;
 
+#ifdef notyet
+       BUILD_BUG_ON(ilog2(VIRTUAL_ENGINES) < I915_NUM_ENGINES);
+#endif
+       ve->base.mask = VIRTUAL_ENGINES;
+
        intel_context_init(&ve->context, &ve->base);
 
        for (n = 0; n < count; n++) {

diff --git a/sys/dev/pci/drm/i915/i915_request.c b/sys/dev/pci/drm/i915/i915_request.c
index 1e37187..b5c0bf1 100644 (file)
--- a/sys/dev/pci/drm/i915/i915_request.c
+++ b/sys/dev/pci/drm/i915/i915_request.c
@@ -141,9 +141,7 @@ static void i915_fence_release(struct dma_fence *fence)
        i915_sw_fence_fini(&rq->semaphore);
 
        /*
-        * Keep one request on each engine for reserved use under mempressure
-        * do not use with virtual engines as this really is only needed for
-        * kernel contexts.
+        * Keep one request on each engine for reserved use under mempressure.
         *
         * We do not hold a reference to the engine here and so have to be
         * very careful in what rq->engine we poke. The virtual engine is
@@ -173,8 +171,7 @@ static void i915_fence_release(struct dma_fence *fence)
         * know that if the rq->execution_mask is a single bit, rq->engine
         * can be a physical engine with the exact corresponding mask.
         */
-       if (!intel_engine_is_virtual(rq->engine) &&
-           is_power_of_2(rq->execution_mask) &&
+       if (is_power_of_2(rq->execution_mask) &&
            !cmpxchg(&rq->engine->request_pool, NULL, rq))
                return;