drm/i915/gvt: Fix MI_FLUSH_DW parsing with correct index check

When MI_FLUSH_DW post write hw status page in index mode, the index
value is in dword step and turned into address offset in cmd dword1.
As status page size is 4K, so can't exceed that.

This fixed upper bound check in cmd parser code which incorrectly
stopped VM for reason of invalid MI_FLUSH_DW write index.

v2:
- Fix upper bound as 4K page size because index value is address offset.

Fixes: be1da7070aea ("drm/i915/gvt: vGPU command scanner")
Cc: stable@vger.kernel.org # v4.10+
Cc: "Zhao, Yan Y" <yan.y.zhao@intel.com>
Reviewed-by: Yan Zhao <yan.y.zhao@intel.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>

diff --git a/drivers/gpu/drm/i915/gvt/cmd_parser.c b/drivers/gpu/drm/i915/gvt/cmd_parser.c
index 77ae634eb11c9e709751b9391a8f392ad9632385..bd95fd6b4ac89a1aa14ca52eaffc50ad1c3894db 100644 (file)
--- a/drivers/gpu/drm/i915/gvt/cmd_parser.c
+++ b/drivers/gpu/drm/i915/gvt/cmd_parser.c
@@ -1446,7 +1446,7 @@ static inline int cmd_address_audit(struct parser_exec_state *s,
        }
 
        if (index_mode) {
-               if (guest_gma >= I915_GTT_PAGE_SIZE / sizeof(u64)) {
+               if (guest_gma >= I915_GTT_PAGE_SIZE) {
                        ret = -EFAULT;
                        goto err;
                }