From: Mario Limonciello mario.limonciello@amd.com
[ 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@infradead.org Signed-off-by: Mario Limonciello mario.limonciello@amd.com Reviewed-by: Robin Murphy robin.murphy@arm.com Reviewed-by: Christoph Hellwig hch@lst.de Link: https://lore.kernel.org/r/20220404204723.9767-2-mario.limonciello@amd.com Signed-off-by: Joerg Roedel jroedel@suse.de Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/iommu/amd/iommu.c | 7 ------- 1 file changed, 7 deletions(-)
diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c index a18b549951bb..74c4ae85e41e 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;