Will Deacon
2021-Mar-30 13:11 UTC
[PATCH 16/18] iommu: remove DOMAIN_ATTR_DMA_USE_FLUSH_QUEUE
On Tue, Mar 16, 2021 at 04:38:22PM +0100, Christoph Hellwig wrote:> From: Robin Murphy <robin.murphy at arm.com> > > Instead make the global iommu_dma_strict paramete in iommu.c canonical by > exporting helpers to get and set it and use those directly in the drivers. > > This make sure that the iommu.strict parameter also works for the AMD and > Intel IOMMU drivers on x86. As those default to lazy flushing a new > IOMMU_CMD_LINE_STRICT is used to turn the value into a tristate to > represent the default if not overriden by an explicit parameter. > > Signed-off-by: Robin Murphy <robin.murphy at arm.com>. > [ported on top of the other iommu_attr changes and added a few small > missing bits] > Signed-off-by: Christoph Hellwig <hch at lst.de> > --- > drivers/iommu/amd/iommu.c | 23 +------- > drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 50 +--------------- > drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h | 1 - > drivers/iommu/arm/arm-smmu/arm-smmu.c | 27 +-------- > drivers/iommu/dma-iommu.c | 9 +-- > drivers/iommu/intel/iommu.c | 64 ++++----------------- > drivers/iommu/iommu.c | 27 ++++++--- > include/linux/iommu.h | 4 +- > 8 files changed, 40 insertions(+), 165 deletions(-)I really like this cleanup, but I can't help wonder if it's going in the wrong direction. With SoCs often having multiple IOMMU instances and a distinction between "trusted" and "untrusted" devices, then having the flush-queue enabled on a per-IOMMU or per-domain basis doesn't sound unreasonable to me, but this change makes it a global property. For example, see the recent patch from Lu Baolu: https://lore.kernel.org/r/20210225061454.2864009-1-baolu.lu at linux.intel.com Will
Robin Murphy
2021-Mar-30 13:19 UTC
[PATCH 16/18] iommu: remove DOMAIN_ATTR_DMA_USE_FLUSH_QUEUE
On 2021-03-30 14:11, Will Deacon wrote:> On Tue, Mar 16, 2021 at 04:38:22PM +0100, Christoph Hellwig wrote: >> From: Robin Murphy <robin.murphy at arm.com> >> >> Instead make the global iommu_dma_strict paramete in iommu.c canonical by >> exporting helpers to get and set it and use those directly in the drivers. >> >> This make sure that the iommu.strict parameter also works for the AMD and >> Intel IOMMU drivers on x86. As those default to lazy flushing a new >> IOMMU_CMD_LINE_STRICT is used to turn the value into a tristate to >> represent the default if not overriden by an explicit parameter. >> >> Signed-off-by: Robin Murphy <robin.murphy at arm.com>. >> [ported on top of the other iommu_attr changes and added a few small >> missing bits] >> Signed-off-by: Christoph Hellwig <hch at lst.de> >> --- >> drivers/iommu/amd/iommu.c | 23 +------- >> drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 50 +--------------- >> drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h | 1 - >> drivers/iommu/arm/arm-smmu/arm-smmu.c | 27 +-------- >> drivers/iommu/dma-iommu.c | 9 +-- >> drivers/iommu/intel/iommu.c | 64 ++++----------------- >> drivers/iommu/iommu.c | 27 ++++++--- >> include/linux/iommu.h | 4 +- >> 8 files changed, 40 insertions(+), 165 deletions(-) > > I really like this cleanup, but I can't help wonder if it's going in the > wrong direction. With SoCs often having multiple IOMMU instances and a > distinction between "trusted" and "untrusted" devices, then having the > flush-queue enabled on a per-IOMMU or per-domain basis doesn't sound > unreasonable to me, but this change makes it a global property.The intent here was just to streamline the existing behaviour of stuffing a global property into a domain attribute then pulling it out again in the illusion that it was in any way per-domain. We're still checking dev_is_untrusted() before making an actual decision, and it's not like we can't add more factors at that point if we want to.> For example, see the recent patch from Lu Baolu: > > https://lore.kernel.org/r/20210225061454.2864009-1-baolu.lu at linux.intel.comErm, this patch is based on that one, it's right there in the context :/ Thanks, Robin.