dmaengine: idxd: Fix crash when the event log is disabled

[ Upstream commit 52d2ede ]

If reporting errors to the event log is not supported by the hardware,
and an error that causes Function Level Reset (FLR) is received, the
driver will try to restore the event log even if it was not allocated.

Also, only try to free the event log if it was properly allocated.

Fixes: 6078a31 ("dmaengine: idxd: Add idxd_device_config_save() and idxd_device_config_restore() helpers")
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>
Link: https://patch.msgid.link/20260121-idxd-fix-flr-on-kernel-queues-v3-v3-2-7ed70658a9d1@intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
[ Only the idxd_device_evl_free() NULL check portion was backported in v6.6.
idxd_device_config_restore() does not exist in v6.6. It was introduced
in 6.14. ]
Signed-off-by: Wenshan Lan <jetlan9@163.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

Author: vcgomes

drivers/dma/idxd/device.c

@@ -810,6 +810,9 @@ static void idxd_device_evl_free(struct idxd_device *idxd)
 	struct device *dev = &idxd->pdev->dev;
 	struct idxd_evl *evl = idxd->evl;
 
+	if (!evl)
+		return;
+
 	gencfg.bits = ioread32(idxd->reg_base + IDXD_GENCFG_OFFSET);
 	if (!gencfg.evl_en)
 		return;