On Sat, Dec 21, 2019 at 03:03:53PM +0000, Tom Murphy wrote:
In the intel iommu driver devices which only support 32bit DMA can't be direct mapped. The implementation of this is weird. Currently we assign it a direct mapped domain and then remove the domain later and replace it with a domain of type IOMMU_DOMAIN_IDENTITY. We should just assign it a domain of type IOMMU_DOMAIN_IDENTITY from the begging rather than needlessly swapping domains.
Signed-off-by: Tom Murphy murphyt7@tcd.ie
drivers/iommu/intel-iommu.c | 88 +++++++++++++------------------------ 1 file changed, 31 insertions(+), 57 deletions(-)
diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c index 0c8d81f56a30..c1ea66467918 100644 --- a/drivers/iommu/intel-iommu.c +++ b/drivers/iommu/intel-iommu.c @@ -5640,7 +5609,12 @@ static int intel_iommu_add_device(struct device *dev) domain = iommu_get_domain_for_dev(dev); dmar_domain = to_dmar_domain(domain); if (domain->type == IOMMU_DOMAIN_DMA) {
if (device_def_domain_type(dev) == IOMMU_DOMAIN_IDENTITY) {
/** We check dma_mask >= dma_get_required_mask(dev) because* 32 bit DMA falls back to non-identity mapping.*/if (device_def_domain_type(dev) == IOMMU_DOMAIN_IDENTITY &&dma_mask >= dma_get_required_mask(dev)) { ret = iommu_request_dm_for_dev(dev); if (ret) { dmar_remove_one_dev_info(dev);-- 2.20.1
Should this be dma_direct_get_required_mask? dma_get_required_mask may return DMA_BIT_MASK(32) -- it callbacks into intel_get_required_mask, but I'm not sure what iommu_no_mapping(dev) will do at this point?