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From: Peter Xu <peterx@redhat.com>
To: "Liu, Yi L" <yi.l.liu@intel.com>
Cc: "jean-philippe@linaro.org" <jean-philippe@linaro.org>,
	"Tian, Kevin" <kevin.tian@intel.com>,
	Jacob Pan <jacob.jun.pan@linux.intel.com>,
	Yi Sun <yi.y.sun@linux.intel.com>,
	Eduardo Habkost <ehabkost@redhat.com>,
	"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
	"mst@redhat.com" <mst@redhat.com>,
	"Tian, Jun J" <jun.j.tian@intel.com>,
	"qemu-devel@nongnu.org" <qemu-devel@nongnu.org>,
	"eric.auger@redhat.com" <eric.auger@redhat.com>,
	"alex.williamson@redhat.com" <alex.williamson@redhat.com>,
	"pbonzini@redhat.com" <pbonzini@redhat.com>,
	"Wu, Hao" <hao.wu@intel.com>, "Sun, Yi Y" <yi.y.sun@intel.com>,
	Richard Henderson <rth@twiddle.net>,
	"david@gibson.dropbear.id.au" <david@gibson.dropbear.id.au>
Subject: Re: [PATCH v1 17/22] intel_iommu: do not pass down pasid bind for PASID #0
Date: Wed, 25 Mar 2020 11:12:05 -0400
Message-ID: <20200325151205.GD354390@xz-x1> (raw)
In-Reply-To: <A2975661238FB949B60364EF0F2C25743A201FC7@SHSMSX104.ccr.corp.intel.com>

On Wed, Mar 25, 2020 at 10:42:25AM +0000, Liu, Yi L wrote:
> > From: Peter Xu < peterx@redhat.com>
> > Sent: Wednesday, March 25, 2020 2:13 AM
> > To: Liu, Yi L <yi.l.liu@intel.com>
> > Subject: Re: [PATCH v1 17/22] intel_iommu: do not pass down pasid bind for PASID
> > #0
> > 
> > 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@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 | 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/.
> 
> Got it.
> 
> > 
> > > +         * 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?
> 
> Before gIOVA is supported by nested translation, it is a must. This requires
> IOVA over 1st level page table is ready in guest kernel, also requires the
> QEMU/VFIO supports to bind the guest IOVA page table to host.
> Currently, guest kernel side is ready. However, QEMU and VFIO side is
> not.

OK:

Reviewed-by: Peter Xu <peterx@redhat.com>

-- 
Peter Xu



  reply index

Thread overview: 80+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-22 12:35 [PATCH v1 00/22] intel_iommu: expose Shared Virtual Addressing to VMs Liu Yi L
2020-03-22 12:35 ` [PATCH v1 01/22] scripts/update-linux-headers: Import iommu.h Liu Yi L
2020-03-22 12:35 ` [PATCH v1 02/22] header file update VFIO/IOMMU vSVA APIs Liu Yi L
2020-03-29 16:32   ` Auger Eric
2020-03-30  7:06     ` Liu, Yi L
2020-03-22 12:36 ` [PATCH v1 03/22] vfio: check VFIO_TYPE1_NESTING_IOMMU support Liu Yi L
2020-03-22 12:36 ` [PATCH v1 04/22] hw/iommu: introduce HostIOMMUContext Liu Yi L
2020-03-23 20:58   ` Peter Xu
2020-03-24 10:00     ` Liu, Yi L
2020-03-22 12:36 ` [PATCH v1 05/22] hw/pci: modify pci_setup_iommu() to set PCIIOMMUOps Liu Yi L
2020-03-22 12:36 ` [PATCH v1 06/22] hw/pci: introduce pci_device_set/unset_iommu_context() Liu Yi L
2020-03-23 21:15   ` Peter Xu
2020-03-24 10:02     ` Liu, Yi L
2020-03-22 12:36 ` [PATCH v1 07/22] intel_iommu: add set/unset_iommu_context callback Liu Yi L
2020-03-23 21:29   ` Peter Xu
2020-03-24 11:15     ` Liu, Yi L
2020-03-24 15:24       ` Peter Xu
2020-03-25  9:37         ` Liu, Yi L
2020-03-22 12:36 ` [PATCH v1 08/22] vfio: init HostIOMMUContext per-container Liu Yi L
     [not found]   ` <20200323213943.GR127076@xz-x1>
2020-03-24 13:03     ` Liu, Yi L
2020-03-24 14:45       ` Peter Xu
2020-03-25  9:30         ` Liu, Yi L
2020-03-22 12:36 ` [PATCH v1 09/22] vfio/common: check PASID alloc/free availability Liu Yi L
2020-03-23 22:06   ` Peter Xu
2020-03-24 11:18     ` Liu, Yi L
2020-03-22 12:36 ` [PATCH v1 10/22] intel_iommu: add virtual command capability support Liu Yi L
2020-03-22 12:36 ` [PATCH v1 11/22] intel_iommu: process PASID cache invalidation Liu Yi L
2020-03-22 12:36 ` [PATCH v1 12/22] intel_iommu: add PASID cache management infrastructure Liu Yi L
2020-03-24 17:32   ` Peter Xu
2020-03-25 12:20     ` Liu, Yi L
2020-03-25 14:52       ` Peter Xu
2020-03-26  6:15         ` Liu, Yi L
2020-03-26 13:57           ` Liu, Yi L
2020-03-26 15:53             ` Peter Xu
2020-03-27  1:33               ` Liu, Yi L
2020-03-22 12:36 ` [PATCH v1 13/22] vfio: add bind stage-1 page table support Liu Yi L
2020-03-24 17:41   ` Peter Xu
2020-03-25  9:49     ` Liu, Yi L
2020-03-22 12:36 ` [PATCH v1 14/22] intel_iommu: bind/unbind guest page table to host Liu Yi L
2020-03-24 17:46   ` Peter Xu
2020-03-25 12:42     ` Liu, Yi L
2020-03-25 14:56       ` Peter Xu
2020-03-26  3:04         ` Liu, Yi L
2020-03-25 12:47     ` Liu, Yi L
2020-03-22 12:36 ` [PATCH v1 15/22] intel_iommu: replay guest pasid bindings " Liu Yi L
2020-03-24 18:00   ` Peter Xu
2020-03-25 13:14     ` Liu, Yi L
2020-03-25 15:06       ` Peter Xu
2020-03-26  3:17         ` Liu, Yi L
2020-03-22 12:36 ` [PATCH v1 16/22] intel_iommu: replay pasid binds after context cache invalidation Liu Yi L
2020-03-24 18:07   ` Peter Xu
2020-03-25 13:18     ` Liu, Yi L
2020-03-22 12:36 ` [PATCH v1 17/22] intel_iommu: do not pass down pasid bind for PASID #0 Liu Yi L
2020-03-24 18:13   ` Peter Xu
2020-03-25 10:42     ` Liu, Yi L
2020-03-25 15:12       ` Peter Xu [this message]
2020-03-26  2:42         ` Liu, Yi L
2020-03-22 12:36 ` [PATCH v1 18/22] vfio: add support for flush iommu stage-1 cache Liu Yi L
2020-03-24 18:19   ` Peter Xu
2020-03-25 10:40     ` Liu, Yi L
2020-03-22 12:36 ` [PATCH v1 19/22] intel_iommu: process PASID-based iotlb invalidation Liu Yi L
2020-03-24 18:26   ` Peter Xu
2020-03-25 13:36     ` Liu, Yi L
2020-03-25 15:15       ` Peter Xu
2020-03-29 11:17         ` Liu, Yi L
2020-03-22 12:36 ` [PATCH v1 20/22] intel_iommu: propagate PASID-based iotlb invalidation to host Liu Yi L
2020-03-24 18:34   ` Peter Xu
2020-03-25 13:21     ` Liu, Yi L
2020-03-26  5:41       ` Liu, Yi L
2020-03-26 13:02         ` Peter Xu
2020-03-26 13:22           ` Peter Xu
2020-03-26 13:33             ` Liu, Yi L
2020-03-26 13:23           ` Liu, Yi L
2020-03-22 12:36 ` [PATCH v1 21/22] intel_iommu: process PASID-based Device-TLB invalidation Liu Yi L
2020-03-24 18:36   ` Peter Xu
2020-03-25  9:19     ` Liu, Yi L
2020-03-22 12:36 ` [PATCH v1 22/22] intel_iommu: modify x-scalable-mode to be string option Liu Yi L
2020-03-24 18:39   ` Peter Xu
2020-03-25 13:22     ` Liu, Yi L
2020-03-22 13:25 ` [PATCH v1 00/22] intel_iommu: expose Shared Virtual Addressing to VMs no-reply

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