On Sun, Mar 22, 2020 at 05:36:14AM -0700, Liu Yi L wrote: > 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@xxxxxxxxx> > Cc: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx> > Cc: Peter Xu <peterx@xxxxxxxxxx> > Cc: Yi Sun <yi.y.sun@xxxxxxxxxxxxxxx> > Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx> > Cc: Richard Henderson <rth@xxxxxxxxxxx> > Cc: Eduardo Habkost <ehabkost@xxxxxxxxxx> > Signed-off-by: Liu Yi L <yi.l.liu@xxxxxxxxx> > --- > 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 1e0ccde..b007715 100644 > --- a/hw/i386/intel_iommu.c > +++ b/hw/i386/intel_iommu.c > @@ -1886,6 +1886,16 @@ static int vtd_bind_guest_pasid(IntelIOMMUState *s, VTDBus *vtd_bus, > struct iommu_gpasid_bind_data *g_bind_data; > int ret = -1; > > + if (pasid < VTD_MIN_HPASID) { > + /* > + * If pasid < VTD_HPASID_MIN, this pasid is not allocated s/VTD_HPASID_MIN/VTD_MIN_HPASID/. > + * 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. What will happen if without this patch? Is it a must? > + */ > + return 0; > + } > + > vtd_dev_icx = vtd_bus->dev_icx[devfn]; > if (!vtd_dev_icx) { > return -EINVAL; > -- > 2.7.4 > -- Peter Xu
