> -----Original Message-----
> From: Duan, Zhenzhong <zhenzhong.duan@intel.com>
> Sent: Thursday, March 26, 2026 5:11 PM
> To: qemu-devel@nongnu.org
> Cc: alex@shazbot.org; clg@redhat.com; eric.auger@redhat.com;
> mst@redhat.com; jasowang@redhat.com; jgg@nvidia.com;
> nicolinc@nvidia.com; skolothumtho@nvidia.com; joao.m.martins@oracle.com;
> clement.mathieu--drif@bull.com; Tian, Kevin <kevin.tian@intel.com>; Liu, Yi L
> <yi.l.liu@intel.com>; Hao, Xudong <xudong.hao@intel.com>; Duan, Zhenzhong
> <zhenzhong.duan@intel.com>
> Subject: [PATCH v2 00/14] intel_iommu: Enable PASID support for passthrough
> device
>
> Hi,
>
> Now we already support first stage translation with passthrough device backed
> by nested translation in host, but only for PASID_0.
>
> Structure VTDAddressSpace includes some elements suitable for emulated
> device and passthrough device without PASID, e.g., address space, different
> memory regions, etc, it is also protected by vtd iommu lock, all these are useless
> and become a burden for passthrough device with PASID.
>
> When there are lots of PASIDs used in one device, the AS and MRs are all
> registered to memory core and impact the whole system performance.
>
> So instead of using VTDAddressSpace to cache pasid entry for each pasid of a
> passthrough device, we define a light weight structure
> VTDAccelPASIDCacheEntry with only necessary elements for each pasid. We will
> use this struct as a parameter to conduct binding/unbinding to nested hwpt, to
> record the current binded nested hwpt and even future PRQ support. It's also
> designed to support PASID_0.
>
> The potential full definition of VTDAccelPASIDCacheEntry may like:
>
> typedef struct VTDAccelPASIDCacheEntry {
> VTDHostIOMMUDevice *vtd_hiod;
> VTDPASIDEntry pasid_entry;
> uint32_t pasid;
> uint32_t fs_hwpt_id;
> uint32_t fault_id;
> int fault_fd;
> QLIST_HEAD(, VTDPRQEntry) vtd_prq_list;
> IOMMUPRINotifier pri_notifier_entry;
> IOMMUPRINotifier *pri_notifier;
> QLIST_ENTRY(VTDAccelPASIDCacheEntry) next;
> } VTDAccelPASIDCacheEntry;
>
> GIT branch:
> https://github.com/yiliu1765/qemu/tree/zhenzhong/iommufd_pasid
>
> PATCH01-06: Some preparing work
> PATCH07-10: Handle PASID entry addition and removal
> PATCH11-12: Support pasid binding and unbinding
> PATCH13-14: Add PASID related check and enable PASID for passthrough device
>
> This patchset depends on a kernel feature enhancement[1] to work.
>
> Tests:
> Tested with DSA device which driver uses 2 PASIDs by default.
>
> Thanks
> Zhenzhong
>
> [1] https://lore.kernel.org/all/20260205023405.41583-1-
> zhenzhong.duan@intel.com/
>
> Changelog:
> v2:
> - move the check "s->pasid > PCI_EXT_CAP_PASID_MAX_WIDTH" to patch5
> (Clement)
> - move #include "hw/core/iommu.h" before #include "hw/core/qdev.h" (liuyi)
> - polish the comment about @Pasid parameter (Liuyi)
> - s/pe/pasid_entry, s/as_it/hiod_it, s/vtd_find_add_pc/vtd_accel_fill_pc (Liuyi)
> - s/VTDACCELPASIDCacheEntry/VTDAccelPASIDCacheEntry (Liuyi)
> - add explanation in code about PASID removal before addition (Liuyi)
> - polish the comment about scope of VTDAccelPASIDCacheEntry vs
> VTDPASIDCacheEntry (Liuyi)
> - add an optimization to bypass PASID entry addition for PASID selective
> pv_inv_dsc (Liuyi)
>
> v1:
> - use naming pattern "XXX_SET_THENAME" same as smmu (Clement)
> - fix s->pasid check (Clement)
>
> RFCv2:
> - extend attach/detach_hwpt() instead of introducing new callbacks (Shammer)
> - Define IOMMU_NO_PASID for device attachment without pasid (Nicolin)
> - update vtd_destroy_old_fs_hwpt()'s parameter for naming consistency
> (Clement)
> - check pasid bits size to be no more than 20 bits (Clement)
> - initialize local variable max_pasid_log2 to 0 (Cédric)
>
>
> Zhenzhong Duan (14):
> vfio/iommufd: Extend attach/detach_hwpt callback implementations with
> pasid
> iommufd: Extend attach/detach_hwpt callbacks to support pasid
> vfio/iommufd: Create nesting parent hwpt with IOMMU_HWPT_ALLOC_PASID
> flag
> intel_iommu: Create the nested hwpt with IOMMU_HWPT_ALLOC_PASID flag
> intel_iommu: Change pasid property from bool to uint8
> intel_iommu: Export some functions
> intel_iommu_accel: Handle PASID entry addition for pc_inv_dsc request
> intel_iommu_accel: Handle PASID entry removal for pc_inv_dsc request
> intel_iommu_accel: Bypass PASID entry addition for just deleted entry
> intel_iommu_accel: Handle PASID entry removal for system reset
> intel_iommu_accel: Support pasid binding/unbinding and PIOTLB flushing
> intel_iommu_accel: drop _lock suffix in
> vtd_flush_host_piotlb_all_locked()
> intel_iommu_accel: Add pasid bits size check
> intel_iommu: Expose flag VIOMMU_FLAG_PASID_SUPPORTED when
> configured
>
> hw/i386/intel_iommu_accel.h | 34 ++-
> hw/i386/intel_iommu_internal.h | 43 +++-
> include/hw/core/iommu.h | 2 +
> include/hw/i386/intel_iommu.h | 4 +-
> include/hw/vfio/vfio-device.h | 1 +
> include/system/iommufd.h | 16 +-
> backends/iommufd.c | 9 +-
> hw/arm/smmuv3-accel.c | 12 +-
> hw/i386/intel_iommu.c | 83 +++----
> hw/i386/intel_iommu_accel.c | 420 +++++++++++++++++++++++++++------
> hw/vfio/device.c | 11 +
> hw/vfio/iommufd.c | 56 +++--
> hw/vfio/trace-events | 4 +-
> 13 files changed, 524 insertions(+), 171 deletions(-)
>
> --
> 2.47.3
Tested-by: Xudong Hao <xudong.hao@intel.com>
DSA PF assignment to VM with vIOMMU scalable mode, dmatest passed in VM.