On Wed, Jul 28, 2021 at 04:58:40PM +0100, Robin Murphy wrote: > The sysfs interface for default domain types exists primarily so users > can choose the performance/security tradeoff relevant to their own > workload. As such, the choice between the policies for DMA domains fits > perfectly as an additional point on that scale - downgrading a > particular device from a strict default to non-strict may be enough to > let it reach the desired level of performance, while still retaining > more peace of mind than with a wide-open identity domain. Now that we've > abstracted non-strict mode as a distinct type of DMA domain, allow it to > be chosen through the user interface as well. > > Signed-off-by: Robin Murphy <robin.mur...@arm.com> > --- > Documentation/ABI/testing/sysfs-kernel-iommu_groups | 2 ++ > drivers/iommu/iommu.c | 2 ++ > 2 files changed, 4 insertions(+) > > diff --git a/Documentation/ABI/testing/sysfs-kernel-iommu_groups > b/Documentation/ABI/testing/sysfs-kernel-iommu_groups > index eae2f1c1e11e..43ba764ba5b7 100644 > --- a/Documentation/ABI/testing/sysfs-kernel-iommu_groups > +++ b/Documentation/ABI/testing/sysfs-kernel-iommu_groups > @@ -42,6 +42,8 @@ Description: /sys/kernel/iommu_groups/<grp_id>/type > shows the type of default > ======== ====================================================== > DMA All the DMA transactions from the device in this group > are translated by the iommu. > + DMA-FQ As above, but using batched invalidation to lazily > + remove translations after use.
It might be useful to desribe the security/performance tradeoff here as well. I guess a normal user is more likely to look at the doc for this sysfs knob than the kernel config or parameters. Thanks, Jean > identity All the DMA transactions from the device in this group > are not translated by the iommu. > auto Change to the type the device was booted with. > diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c > index eecb5657de69..5a08e0806cbb 100644 > --- a/drivers/iommu/iommu.c > +++ b/drivers/iommu/iommu.c > @@ -3265,6 +3265,8 @@ static ssize_t iommu_group_store_type(struct > iommu_group *group, > req_type = IOMMU_DOMAIN_IDENTITY; > else if (sysfs_streq(buf, "DMA")) > req_type = IOMMU_DOMAIN_DMA; > + else if (sysfs_streq(buf, "DMA-FQ")) > + req_type = IOMMU_DOMAIN_DMA_FQ; > else if (sysfs_streq(buf, "auto")) > req_type = 0; > else > -- > 2.25.1 > > _______________________________________________ > iommu mailing list > iommu@lists.linux-foundation.org > https://lists.linuxfoundation.org/mailman/listinfo/iommu _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu