Patch "net: ipa: fix table alignment requirement" has been added to the 5.10-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    net: ipa: fix table alignment requirement

to the 5.10-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     net-ipa-fix-table-alignment-requirement.patch
and it can be found in the queue-5.10 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 33e2fc4a1b5ba3ab1686201d0c60be50f7f1d590
Author: Alex Elder <elder@xxxxxxxxxx>
Date:   Thu Mar 18 13:59:29 2021 -0500

    net: ipa: fix table alignment requirement
    
    [ Upstream commit e5d4e96b44cf20330c970c3e30ea0a8c3a23feca ]
    
    We currently have a build-time check to ensure that the minimum DMA
    allocation alignment satisfies the constraint that IPA filter and
    route tables must point to rules that are 128-byte aligned.
    
    But what's really important is that the actual allocated DMA memory
    has that alignment, even if the minimum is smaller than that.
    
    Remove the BUILD_BUG_ON() call checking against minimim DMA alignment
    and instead verify at rutime that the allocated memory is properly
    aligned.
    
    Signed-off-by: Alex Elder <elder@xxxxxxxxxx>
    Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
    Stable-dep-of: cf412ec33325 ("net: ipa: properly limit modem routing table use")
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/net/ipa/ipa_table.c b/drivers/net/ipa/ipa_table.c
index f26cb9d706da..45e1d68b4694 100644
--- a/drivers/net/ipa/ipa_table.c
+++ b/drivers/net/ipa/ipa_table.c
@@ -118,14 +118,6 @@
 /* Check things that can be validated at build time. */
 static void ipa_table_validate_build(void)
 {
-	/* IPA hardware accesses memory 128 bytes at a time.  Addresses
-	 * referred to by entries in filter and route tables must be
-	 * aligned on 128-byte byte boundaries.  The only rule address
-	 * ever use is the "zero rule", and it's aligned at the base
-	 * of a coherent DMA allocation.
-	 */
-	BUILD_BUG_ON(ARCH_DMA_MINALIGN % IPA_TABLE_ALIGN);
-
 	/* Filter and route tables contain DMA addresses that refer
 	 * to filter or route rules.  But the size of a table entry
 	 * is 64 bits regardless of what the size of an AP DMA address
@@ -669,6 +661,18 @@ int ipa_table_init(struct ipa *ipa)
 	if (!virt)
 		return -ENOMEM;
 
+	/* We put the "zero rule" at the base of our table area.  The IPA
+	 * hardware requires rules to be aligned on a 128-byte boundary.
+	 * Make sure the allocation satisfies this constraint.
+	 */
+	if (addr % IPA_TABLE_ALIGN) {
+		dev_err(dev, "table address %pad not %u-byte aligned\n",
+			&addr, IPA_TABLE_ALIGN);
+		dma_free_coherent(dev, size, virt, addr);
+
+		return -ERANGE;
+	}
+
 	ipa->table_virt = virt;
 	ipa->table_addr = addr;