From 3cd508a8c1379427afb5e16c2e0a7c986d907853 Mon Sep 17 00:00:00 2001
From: Robin Murphy <robin.murphy@arm.com>
Date: Wed, 17 Oct 2018 21:32:58 +0100
Subject: [PATCH] iommu/arm-smmu-v3: Fix big-endian CMD_SYNC writes
Git-commit: 3cd508a8c1379427afb5e16c2e0a7c986d907853
Patch-mainline: v5.0-rc1
References: bsc#1111666
When we insert the sync sequence number into the CMD_SYNC.MSIData field,
we do so in CPU-native byte order, before writing out the whole command
as explicitly little-endian dwords. Thus on big-endian systems, the SMMU
will receive and write back a byteswapped version of sync_nr, which would
be perfect if it were targeting a similarly-little-endian ITS, but since
it's actually writing back to memory being polled by the CPUs, they're
going to end up seeing the wrong thing.
Since the SMMU doesn't care what the MSIData actually contains, the
minimal-overhead solution is to simply add an extra byteswap initially,
such that it then writes back the big-endian format directly.
Cc: <stable@vger.kernel.org>
Fixes: 37de98f8f1cf ("iommu/arm-smmu-v3: Use CMD_SYNC completion MSI")
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Acked-by: Takashi Iwai <tiwai@suse.de>
---
drivers/iommu/arm-smmu-v3.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
index 6947ccf26512..71eda422c926 100644
--- a/drivers/iommu/arm-smmu-v3.c
+++ b/drivers/iommu/arm-smmu-v3.c
@@ -828,7 +828,13 @@ static int arm_smmu_cmdq_build_cmd(u64 *cmd, struct arm_smmu_cmdq_ent *ent)
cmd[0] |= FIELD_PREP(CMDQ_SYNC_0_CS, CMDQ_SYNC_0_CS_SEV);
cmd[0] |= FIELD_PREP(CMDQ_SYNC_0_MSH, ARM_SMMU_SH_ISH);
cmd[0] |= FIELD_PREP(CMDQ_SYNC_0_MSIATTR, ARM_SMMU_MEMATTR_OIWB);
- cmd[0] |= FIELD_PREP(CMDQ_SYNC_0_MSIDATA, ent->sync.msidata);
+ /*
+ * Commands are written little-endian, but we want the SMMU to
+ * receive MSIData, and thus write it back to memory, in CPU
+ * byte order, so big-endian needs an extra byteswap here.
+ */
+ cmd[0] |= FIELD_PREP(CMDQ_SYNC_0_MSIDATA,
+ cpu_to_le32(ent->sync.msidata));
cmd[1] |= ent->sync.msiaddr & CMDQ_SYNC_1_MSIADDR_MASK;
break;
default:
--
2.16.4