i915: fix invalid opcode exception on cpus without clflush

i915_flush_ttm was unconditionally executing a clflush instruction
to (obviously) flush the cache. Instead, check if the cpu supports
clflush, and if not, fall back to calling wbinvd to flush the entire
cache.

Signed-off-by: Kyle McMartin <kmcmartin@redhat.com>

diff --git a/linux-core/i915_buffer.c b/linux-core/i915_buffer.c
index 3dd236d..0806747 100644 (file)
--- a/linux-core/i915_buffer.c
+++ b/linux-core/i915_buffer.c
@@ -286,7 +286,18 @@ void i915_flush_ttm(struct drm_ttm *ttm)
                return;
 
        DRM_MEMORYBARRIER();
+
+#ifdef CONFIG_X86_32
+       /* Hopefully nobody has built an x86-64 processor without clflush */
+       if (!cpu_has_clflush) {
+               wbinvd();
+               DRM_MEMORYBARRIER();
+               return;
+       }
+#endif
+
        for (i = ttm->num_pages - 1; i >= 0; i--)
                drm_cache_flush_page(drm_ttm_get_page(ttm, i));
+
        DRM_MEMORYBARRIER();
 }