Hi Joerg, > -----Original Message----- > From: Prakhya, Sai Praneeth <sai.praneeth.prak...@intel.com> > Sent: Thursday, June 4, 2020 6:32 PM > To: iommu@lists.linux-foundation.org > Cc: Prakhya, Sai Praneeth <sai.praneeth.prak...@intel.com>; Christoph Hellwig > <h...@lst.de>; Joerg Roedel <j...@8bytes.org>; Raj, Ashok > <ashok....@intel.com>; Will Deacon <will.dea...@arm.com>; Lu Baolu > <baolu...@linux.intel.com>; Mehta, Sohil <sohil.me...@intel.com>; Robin > Murphy <robin.mur...@arm.com>; Jacob Pan <jacob.jun....@linux.intel.com> > Subject: [PATCH V4 0/3] iommu: Add support to change default domain of an > iommu group > > Presently, the default domain of an iommu group is allocated during boot time > and it cannot be changed later. So, the device would typically be either in > identity (pass_through) mode or the device would be in DMA mode as long as > the system is up and running. There is no way to change the default domain > type > dynamically i.e. after booting, a device cannot switch between identity mode > and DMA mode. > > Assume a use case wherein the privileged user would want to use the device in > pass-through mode when the device is used for host so that it would be high > performing. Presently, this is not supported. Hence add support to change the > default domain of an iommu group dynamically. > > Support this by writing to a sysfs file, namely > "/sys/kernel/iommu_groups/<grp_id>/type". > > Testing: > -------- > Tested by dynamically changing storage device (nvme) from 1. identity mode to > DMA and making sure file transfer works 2. DMA mode to identity mode and > making sure file transfer works Tested only for intel_iommu/vt-d. Would > appreciate if someone could test on AMD and ARM based machines. > > Based on iommu maintainer's 'next' branch. > > Changes from V3: > ---------------- > 1. Made changes to commit message as suggested by Baolu. > 2. Don't pass "prev_dom" and "dev" as parameters to > iommu_change_dev_def_domain(). Instead get them from group. > 3. Sanitize the logic to validate user default domain type request. The logic > remains same but is implmented differently. > 4. Push lot of error checking into iommu_change_dev_def_domain() from > iommu_group_store_type(). > 5. iommu_change_dev_def_domain() takes/releases group mutex as needed. > So, it > shouldn't be called holding a group mutex. > 6. Use pr_err_ratelimited() instead of pr_err() to avoid DOS attack.
Could you please review this patch set and let me know if you have any comments? Regards, Sai _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
