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[RFC v11 20/25] intel_iommu: do not pass down pasid bind for PASID #0
From: |
Liu Yi L |
Subject: |
[RFC v11 20/25] intel_iommu: do not pass down pasid bind for PASID #0 |
Date: |
Wed, 3 Mar 2021 04:38:22 +0800 |
RID_PASID field was introduced in VT-d 3.0 spec, it is used
for DMA requests w/o PASID in scalable mode VT-d. It is also
known as IOVA. And in VT-d 3.1 spec, there is definition on it:
"Implementations not supporting RID_PASID capability
(ECAP_REG.RPS is 0b), use a PASID value of 0 to perform
address translation for requests without PASID."
This patch adds a check against the PASIDs which are going to be
bound to device. For PASID #0, it is not necessary to pass down
pasid bind request for it since PASID #0 is used as RID_PASID for
DMA requests without pasid. Further reason is current Intel vIOMMU
supports gIOVA by shadowing guest 2nd level page table. However,
in future, if guest IOMMU driver uses 1st level page table to store
IOVA mappings, then guest IOVA support will also be done via nested
translation. When gIOVA is over FLPT, then vIOMMU should pass down
the pasid bind request for PASID #0 to host, host needs to bind the
guest IOVA page table to a proper PASID. e.g. PASID value in RID_PASID
field for PF/VF if ECAP_REG.RPS is clear or default PASID for ADI
(Assignable Device Interface in Scalable IOV solution).
IOVA over FLPT support on Intel VT-d:
https://lore.kernel.org/linux-iommu/20191219031634.15168-1-baolu.lu@linux.intel.com/
Cc: Kevin Tian <kevin.tian@intel.com>
Cc: Jacob Pan <jacob.jun.pan@linux.intel.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Yi Sun <yi.y.sun@linux.intel.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Eduardo Habkost <ehabkost@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Liu Yi L <yi.l.liu@intel.com>
---
hw/i386/intel_iommu.c | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
index c99fd3b167..740dc63090 100644
--- a/hw/i386/intel_iommu.c
+++ b/hw/i386/intel_iommu.c
@@ -1915,6 +1915,16 @@ static int vtd_bind_guest_pasid(IntelIOMMUState *s,
VTDBus *vtd_bus,
HostIOMMUContext *iommu_ctx;
int ret = -1;
+ if (pasid < VTD_HPASID_MIN) {
+ /*
+ * If pasid < VTD_HPASID_MIN, this pasid is not allocated
+ * from host. No need to pass down the changes on it to host.
+ * TODO: when IOVA over FLPT is ready, this switch should be
+ * refined.
+ */
+ return 0;
+ }
+
vtd_dev_icx = vtd_bus->dev_icx[devfn];
if (!vtd_dev_icx) {
/* means no need to go further, e.g. for emulated devices */
--
2.25.1
- [RFC v11 10/25] hw/pci: introduce pci_device_set/unset_iommu_context(), (continued)
- [RFC v11 10/25] hw/pci: introduce pci_device_set/unset_iommu_context(), Liu Yi L, 2021/03/02
- [RFC v11 11/25] intel_iommu: add set/unset_iommu_context callback, Liu Yi L, 2021/03/02
- [RFC v11 12/25] vfio: add HostIOMMUContext support, Liu Yi L, 2021/03/02
- [RFC v11 13/25] vfio: init HostIOMMUContext per-container, Liu Yi L, 2021/03/02
- [RFC v11 14/25] intel_iommu: sync IOMMU nesting cap info for assigned devices, Liu Yi L, 2021/03/02
- [RFC v11 15/25] intel_iommu: add virtual command capability support, Liu Yi L, 2021/03/02
- [RFC v11 16/25] intel_iommu: process PASID cache invalidation, Liu Yi L, 2021/03/02
- [RFC v11 17/25] intel_iommu: add PASID cache management infrastructure, Liu Yi L, 2021/03/02
- [RFC v11 18/25] intel_iommu: bind/unbind guest page table to host, Liu Yi L, 2021/03/02
- [RFC v11 19/25] intel_iommu: replay pasid binds after context cache invalidation, Liu Yi L, 2021/03/02
- [RFC v11 20/25] intel_iommu: do not pass down pasid bind for PASID #0,
Liu Yi L <=
- [RFC v11 21/25] vfio: add support for flush iommu stage-1 cache, Liu Yi L, 2021/03/02
- [RFC v11 22/25] intel_iommu: process PASID-based iotlb invalidation, Liu Yi L, 2021/03/02
- [RFC v11 23/25] intel_iommu: propagate PASID-based iotlb invalidation to host, Liu Yi L, 2021/03/02
- [RFC v11 24/25] intel_iommu: process PASID-based Device-TLB invalidation, Liu Yi L, 2021/03/02
- [RFC v11 25/25] intel_iommu: modify x-scalable-mode to be string option, Liu Yi L, 2021/03/02