From c5a4e8eb683c6a80c6907c12acf7b66665ef4b0b Mon Sep 17 00:00:00 2001
From: Johannes Berg <johannes.berg@intel.com>
Date: Thu, 14 Nov 2019 09:26:20 +0100
Subject: [PATCH] iwlwifi: pcie: detect the DMA bug and warn if it happens
Git-commit: c5a4e8eb683c6a80c6907c12acf7b66665ef4b0b
Patch-mainline: v5.5
References: jsc#SLE-13430
Warn if the DMA bug is going to happen. We don't have a good
way of actually aborting in this case and we have workarounds
in place for the cases where it happens, but in order to not
be surprised add a safety-check and warn.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Acked-by: Takashi Iwai <tiwai@suse.de>
---
drivers/net/wireless/intel/iwlwifi/pcie/tx-gen2.c | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/drivers/net/wireless/intel/iwlwifi/pcie/tx-gen2.c b/drivers/net/wireless/intel/iwlwifi/pcie/tx-gen2.c
index 8abadfbc793a..a2dc380ac17c 100644
--- a/drivers/net/wireless/intel/iwlwifi/pcie/tx-gen2.c
+++ b/drivers/net/wireless/intel/iwlwifi/pcie/tx-gen2.c
@@ -231,6 +231,17 @@ static int iwl_pcie_gen2_set_tb(struct iwl_trans *trans,
int idx = iwl_pcie_gen2_get_num_tbs(trans, tfd);
struct iwl_tfh_tb *tb;
+ /*
+ * Only WARN here so we know about the issue, but we mess up our
+ * unmap path because not every place currently checks for errors
+ * returned from this function - it can only return an error if
+ * there's no more space, and so when we know there is enough we
+ * don't always check ...
+ */
+ WARN(crosses_4g_boundary(addr, len),
+ "possible DMA problem with iova:0x%llx, len:%d\n",
+ (unsigned long long)addr, len);
+
if (WARN_ON(idx >= IWL_TFH_NUM_TBS))
return -EINVAL;
tb = &tfd->tbs[idx];
--
2.16.4