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[RFC v6 20/25] intel_iommu: do not pass down pasid bind for PASID #0
From: |
Liu Yi L |
Subject: |
[RFC v6 20/25] intel_iommu: do not pass down pasid bind for PASID #0 |
Date: |
Thu, 11 Jun 2020 05:54:19 -0700 |
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://lkml.org/lkml/2019/9/23/297
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 a8431c2..b113aa5 100644
--- a/hw/i386/intel_iommu.c
+++ b/hw/i386/intel_iommu.c
@@ -1893,6 +1893,16 @@ 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 */
--
2.7.4
- [RFC v6 00/25] intel_iommu: expose Shared Virtual Addressing to VMs, Liu Yi L, 2020/06/11
- [RFC v6 06/25] vfio: pass nesting iommu requirement into vfio_get_group(), Liu Yi L, 2020/06/11
- [RFC v6 19/25] intel_iommu: replay pasid binds after context cache invalidation, Liu Yi L, 2020/06/11
- [RFC v6 07/25] vfio: check VFIO_TYPE1_NESTING_IOMMU support, Liu Yi L, 2020/06/11
- [RFC v6 01/25] scripts/update-linux-headers: Import iommu.h, Liu Yi L, 2020/06/11
- [RFC v6 08/25] hw/iommu: introduce HostIOMMUContext, Liu Yi L, 2020/06/11
- [RFC v6 12/25] vfio: init HostIOMMUContext per-container, Liu Yi L, 2020/06/11
- [RFC v6 02/25] header file update VFIO/IOMMU vSVA APIs kernel 5.7-rc4, Liu Yi L, 2020/06/11
- [RFC v6 14/25] intel_iommu: process PASID cache invalidation, Liu Yi L, 2020/06/11
- [RFC v6 20/25] intel_iommu: do not pass down pasid bind for PASID #0,
Liu Yi L <=
- [RFC v6 15/25] intel_iommu: add PASID cache management infrastructure, Liu Yi L, 2020/06/11
- [RFC v6 03/25] hw/pci: modify pci_setup_iommu() to set PCIIOMMUOps, Liu Yi L, 2020/06/11
- [RFC v6 09/25] hw/pci: introduce pci_device_set/unset_iommu_context(), Liu Yi L, 2020/06/11
- [RFC v6 16/25] vfio: add bind stage-1 page table support, Liu Yi L, 2020/06/11
- [RFC v6 23/25] intel_iommu: propagate PASID-based iotlb invalidation to host, Liu Yi L, 2020/06/11
- [RFC v6 13/25] intel_iommu: add virtual command capability support, Liu Yi L, 2020/06/11
- [RFC v6 05/25] intel_iommu: add get_iommu_attr() callback, Liu Yi L, 2020/06/11
- [RFC v6 17/25] intel_iommu: sync IOMMU nesting cap info for assigned devices, Liu Yi L, 2020/06/11
- [RFC v6 11/25] vfio/common: provide PASID alloc/free hooks, Liu Yi L, 2020/06/11
- [RFC v6 18/25] intel_iommu: bind/unbind guest page table to host, Liu Yi L, 2020/06/11