iommu/amd: use full 64-bit value in build_completion_wait()

[ Upstream commit 94a568c ]

We started using a 64 bit completion value.  Unfortunately, we only
stored the low 32-bits, so a very large completion value would never
be matched in iommu_completion_wait().

Fixes: c69d89a ("iommu/amd: Use 4K page for completion wait write-back semaphore")
Signed-off-by: John Sperbeck <jsperbeck@google.com>
Link: https://lore.kernel.org/r/20220801192229.3358786-1-jsperbeck@google.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>

drivers/iommu/amd/iommu.c

@@ -874,7 +874,8 @@ static void build_completion_wait(struct iommu_cmd *cmd,
 	memset(cmd, 0, sizeof(*cmd));
 	cmd->data[0] = lower_32_bits(paddr) | CMD_COMPL_WAIT_STORE_MASK;
 	cmd->data[1] = upper_32_bits(paddr);
-	cmd->data[2] = data;
+	cmd->data[2] = lower_32_bits(data);
+	cmd->data[3] = upper_32_bits(data);
 	CMD_SET_TYPE(cmd, CMD_COMPL_WAIT);
 }