This is a note to let you know that I've just added the patch titled
iommu/amd: Enable swiotlb in all cases
to the 5.18-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:
iommu-amd-enable-swiotlb-in-all-cases.patch
and it can be found in the queue-5.18 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit b402056d57135f32b042947777408c0897c6e874
Author: Mario Limonciello <mario.limonciello@xxxxxxx>
Date: Mon Apr 4 15:47:22 2022 -0500
iommu/amd: Enable swiotlb in all cases
[ Upstream commit 121660bba631104154b7c15e88f208c48c8c3297 ]
Previously the AMD IOMMU would only enable SWIOTLB in certain
circumstances:
* IOMMU in passthrough mode
* SME enabled
This logic however doesn't work when an untrusted device is plugged in
that doesn't do page aligned DMA transactions. The expectation is
that a bounce buffer is used for those transactions.
This fails like this:
swiotlb buffer is full (sz: 4096 bytes), total 0 (slots), used 0 (slots)
That happens because the bounce buffers have been allocated, followed by
freed during startup but the bounce buffering code expects that all IOMMUs
have left it enabled.
Remove the criteria to set up bounce buffers on AMD systems to ensure
they're always available for supporting untrusted devices.
Fixes: 82612d66d51d ("iommu: Allow the dma-iommu api to use bounce buffers")
Suggested-by: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Signed-off-by: Mario Limonciello <mario.limonciello@xxxxxxx>
Reviewed-by: Robin Murphy <robin.murphy@xxxxxxx>
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Link: https://lore.kernel.org/r/20220404204723.9767-2-mario.limonciello@xxxxxxx
Signed-off-by: Joerg Roedel <jroedel@xxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
index a1ada7bff44e..079694f894b8 100644
--- a/drivers/iommu/amd/iommu.c
+++ b/drivers/iommu/amd/iommu.c
@@ -1838,17 +1838,10 @@ void amd_iommu_domain_update(struct protection_domain *domain)
amd_iommu_domain_flush_complete(domain);
}
-static void __init amd_iommu_init_dma_ops(void)
-{
- swiotlb = (iommu_default_passthrough() || sme_me_mask) ? 1 : 0;
-}
-
int __init amd_iommu_init_api(void)
{
int err;
- amd_iommu_init_dma_ops();
-
err = bus_set_iommu(&pci_bus_type, &amd_iommu_ops);
if (err)
return err;
