From: Joerg Roedel <[email protected]> Using Passthrough mode when SME is active causes certain devices to use the SWIOTLB bounce buffer. The bounce buffer code has an upper limit of 256kb for the size of DMA allocations, which is too small for certain devices and causes them to fail.
With this patch we enable IOMMU by default when SME is active in the system, making the default configuration work for more systems than it does now. Users that don't want IOMMUs to be enabled still can disable them with kernel parameters. Signed-off-by: Joerg Roedel <[email protected]> --- drivers/iommu/iommu.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c index 62cae6db0970..fbe1aa51bce9 100644 --- a/drivers/iommu/iommu.c +++ b/drivers/iommu/iommu.c @@ -104,6 +104,12 @@ static int __init iommu_subsys_init(void) else iommu_def_domain_type = IOMMU_DOMAIN_DMA; + if ((iommu_def_domain_type == IOMMU_DOMAIN_IDENTITY) && + sme_active()) { + pr_info("SME detected - Disabling default IOMMU passthrough\n"); + iommu_def_domain_type = IOMMU_DOMAIN_DMA; + } + pr_info("Default domain type: %s\n", iommu_domain_type_str(iommu_def_domain_type)); -- 2.17.1
