RE: [PATCH v1 19/22] intel_iommu: process PASID-based iotlb invalidation

Liu, Yi L
2020-03-29T11:17:21Z

> From: Peter Xu <peterx@redhat.com>
> Sent: Wednesday, March 25, 2020 11:16 PM
> To: Liu, Yi L <yi.l.liu@intel.com>
> Subject: Re: [PATCH v1 19/22] intel_iommu: process PASID-based iotlb invalidation
>
> On Wed, Mar 25, 2020 at 01:36:03PM +0000, Liu, Yi L wrote:
> > > From: Peter Xu <peterx@redhat.com>
> > > Sent: Wednesday, March 25, 2020 2:26 AM
> > > To: Liu, Yi L <yi.l.liu@intel.com>
> > > Subject: Re: [PATCH v1 19/22] intel_iommu: process PASID-based iotlb
> > > invalidation
> > >
> > > On Sun, Mar 22, 2020 at 05:36:16AM -0700, Liu Yi L wrote:
> > > > This patch adds the basic PASID-based iotlb (piotlb) invalidation
> > > > support. piotlb is used during walking Intel VT-d 1st level page
> > > > table. This patch only adds the basic processing. Detailed
> > > > handling will be added in next patch.
> > > >
> > > > 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>
> > > > Signed-off-by: Liu Yi L <yi.l.liu@intel.com>
> > > > ---
> > > > hw/i386/intel_iommu.c | 57
> > > ++++++++++++++++++++++++++++++++++++++++++
> > > > hw/i386/intel_iommu_internal.h | 13 ++++++++++
> > > > 2 files changed, 70 insertions(+)
> > > >
> > > > diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c index
> > > > b007715..b9ac07d 100644
> > > > --- a/hw/i386/intel_iommu.c
> > > > +++ b/hw/i386/intel_iommu.c
> > > > @@ -3134,6 +3134,59 @@ static bool
> > > > vtd_process_pasid_desc(IntelIOMMUState
> > > *s,
> > > > return (ret == 0) ? true : false; }
> > > >
> > > > +static void vtd_piotlb_pasid_invalidate(IntelIOMMUState *s,
> > > > + uint16_t domain_id,
> > > > + uint32_t pasid) { }
> > > > +
> > > > +static void vtd_piotlb_page_invalidate(IntelIOMMUState *s, uint16_t
> domain_id,
> > > > + uint32_t pasid, hwaddr addr, uint8_t
> > > > +am, bool ih) { }
> > > > +
> > > > +static bool vtd_process_piotlb_desc(IntelIOMMUState *s,
> > > > + VTDInvDesc *inv_desc) {
> > > > + uint16_t domain_id;
> > > > + uint32_t pasid;
> > > > + uint8_t am;
> > > > + hwaddr addr;
> > > > +
> > > > + if ((inv_desc->val[0] & VTD_INV_DESC_PIOTLB_RSVD_VAL0) ||
> > > > + (inv_desc->val[1] & VTD_INV_DESC_PIOTLB_RSVD_VAL1)) {
> > > > + error_report_once("non-zero-field-in-piotlb_inv_desc hi: 0x%" PRIx64
> > > > + " lo: 0x%" PRIx64, inv_desc->val[1], inv_desc->val[0]);
> > > > + return false;
> > > > + }
> > > > +
> > > > + domain_id = VTD_INV_DESC_PIOTLB_DID(inv_desc->val[0]);
> > > > + pasid = VTD_INV_DESC_PIOTLB_PASID(inv_desc->val[0]);
> > > > + switch (inv_desc->val[0] & VTD_INV_DESC_IOTLB_G) {
> > > > + case VTD_INV_DESC_PIOTLB_ALL_IN_PASID:
> > > > + vtd_piotlb_pasid_invalidate(s, domain_id, pasid);
> > > > + break;
> > > > +
> > > > + case VTD_INV_DESC_PIOTLB_PSI_IN_PASID:
> > > > + am = VTD_INV_DESC_PIOTLB_AM(inv_desc->val[1]);
> > > > + addr = (hwaddr) VTD_INV_DESC_PIOTLB_ADDR(inv_desc->val[1]);
> > > > + if (am > VTD_MAMV) {
> > >
> > > I saw this of spec 10.4.2, MAMV:
> > >
> > > Independent of value reported in this field, implementations
> > > supporting SMTS must support address-selective PASID-based
> > > IOTLB invalidations (p_iotlb_inv_dsc) with any defined address
> > > mask.
> > >
> > > Does it mean we should even support larger AM?
> > >
> > > Besides that, the patch looks good to me.
> >
> > I don't think so. This field is for second-level table in scalable
> > mode and the translation table in legacy mode. For first-level table,
> > it always supports page selective invalidation and all the supported
> > masks regardless of the PSI support bit and the MAMV field in the CAP_REG.
>
> Yes that's exactly what I wanted to ask... Let me try again.
>
> I thought VTD_MAMV was only for 2nd level page table, not for pasid-iotlb
> invalidations. So I think we should remove this "if"
> check (that corresponds to "we should even support larger AM"), right?

Right. I confirmed with spec owner. Will remove it. :-)

Regards,
Yi Liu