Re: [RFC v2 14/22] vfio/pci: add iommu_context notifier for pasid bind/unbind

[Peter Xu]

On Wed, Nov 06, 2019 at 12:22:46PM +0000, Liu, Yi L wrote:
> > From: David Gibson
> > Sent: Tuesday, November 5, 2019 12:02 AM
> > To: Liu, Yi L <address@hidden>
> > Subject: Re: [RFC v2 14/22] vfio/pci: add iommu_context notifier for pasid
> > bind/unbind
> > 
> > On Thu, Oct 24, 2019 at 08:34:35AM -0400, Liu Yi L wrote:
> > > This patch adds notifier for pasid bind/unbind. VFIO registers this
> > > notifier to listen to the dual-stage translation (a.k.a. nested
> > > translation) configuration changes and propagate to host. Thus vIOMMU
> > > is able to set its translation structures to host.
> > >
> > > Cc: Kevin Tian <address@hidden>
> > > Cc: Jacob Pan <address@hidden>
> > > Cc: Peter Xu <address@hidden>
> > > Cc: Eric Auger <address@hidden>
> > > Cc: Yi Sun <address@hidden>
> > > Cc: David Gibson <address@hidden>
> > > Signed-off-by: Liu Yi L <address@hidden>
> > > ---
> > >  hw/vfio/pci.c            | 39 +++++++++++++++++++++++++++++++++++++++
> > >  include/hw/iommu/iommu.h | 11 +++++++++++
> > >  2 files changed, 50 insertions(+)
> > >
> > > diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
> > > index 8721ff6..012b8ed 100644
> > > --- a/hw/vfio/pci.c
> > > +++ b/hw/vfio/pci.c
> > > @@ -2767,6 +2767,41 @@ static void
> > vfio_iommu_pasid_free_notify(IOMMUCTXNotifier *n,
> > >      pasid_req->free_result = ret;
> > >  }
> > >
> > > +static void vfio_iommu_pasid_bind_notify(IOMMUCTXNotifier *n,
> > > +                                         IOMMUCTXEventData *event_data)
> > > +{
> > > +#ifdef __linux__
> > 
> > Is hw/vfio/pci.c even built on non-linux hosts?
> 
> I'm not quite sure. It's based a comment from RFC v1. I think it could somehow
> prevent compiling issue when doing code porting. So I added it. If it's 
> impossible
> to build on non-linux hosts per your experience, I can remove it to make 
> things
> simple.

To my understanding this should not be needed because VFIO doesn't
work with non-linux after all (as said)... while...

> 
> > > +    VFIOIOMMUContext *giommu_ctx = container_of(n, VFIOIOMMUContext, n);
> > > +    VFIOContainer *container = giommu_ctx->container;
> > > +    IOMMUCTXPASIDBindData *pasid_bind =
> > > +                              (IOMMUCTXPASIDBindData *) event_data->data;
> > > +    struct vfio_iommu_type1_bind *bind;
> > > +    struct iommu_gpasid_bind_data *bind_data;
> > > +    unsigned long argsz;
> > > +
> > > +    argsz = sizeof(*bind) + sizeof(*bind_data);
> > > +    bind = g_malloc0(argsz);
> > > +    bind->argsz = argsz;
> > > +    bind->bind_type = VFIO_IOMMU_BIND_GUEST_PASID;
> > > +    bind_data = (struct iommu_gpasid_bind_data *) &bind->data;
> > > +    *bind_data = *pasid_bind->data;
> > > +
> > > +    if (pasid_bind->flag & IOMMU_CTX_BIND_PASID) {
> > > +        if (ioctl(container->fd, VFIO_IOMMU_BIND, bind) != 0) {
> > > +            error_report("%s: pasid (%llu:%llu) bind failed: %d", 
> > > __func__,
> > > +                         bind_data->gpasid, bind_data->hpasid, -errno);
> > > +        }
> > > +    } else if (pasid_bind->flag & IOMMU_CTX_UNBIND_PASID) {
> > > +        if (ioctl(container->fd, VFIO_IOMMU_UNBIND, bind) != 0) {
> > > +            error_report("%s: pasid (%llu:%llu) unbind failed: %d", 
> > > __func__,
> > > +                         bind_data->gpasid, bind_data->hpasid, -errno);
> > > +        }
> > > +    }
> > > +
> > > +    g_free(bind);
> > > +#endif
> > > +}
> > > +
> > >  static void vfio_realize(PCIDevice *pdev, Error **errp)
> > >  {
> > >      VFIOPCIDevice *vdev = PCI_VFIO(pdev);
> > > @@ -3079,6 +3114,10 @@ static void vfio_realize(PCIDevice *pdev, Error 
> > > **errp)
> > >                                           iommu_context,
> > >                                           vfio_iommu_pasid_free_notify,
> > >                                           IOMMU_CTX_EVENT_PASID_FREE);
> > > +        vfio_register_iommu_ctx_notifier(vdev,
> > > +                                         iommu_context,
> > > +                                         vfio_iommu_pasid_bind_notify,
> > > +                                         IOMMU_CTX_EVENT_PASID_BIND);
> > >      }
> > >
> > >      return;
> > > diff --git a/include/hw/iommu/iommu.h b/include/hw/iommu/iommu.h
> > > index 4352afd..4f21aa1 100644
> > > --- a/include/hw/iommu/iommu.h
> > > +++ b/include/hw/iommu/iommu.h
> > > @@ -33,6 +33,7 @@ typedef struct IOMMUContext IOMMUContext;
> > >  enum IOMMUCTXEvent {
> > >      IOMMU_CTX_EVENT_PASID_ALLOC,
> > >      IOMMU_CTX_EVENT_PASID_FREE,
> > > +    IOMMU_CTX_EVENT_PASID_BIND,
> > >      IOMMU_CTX_EVENT_NUM,
> > >  };
> > >  typedef enum IOMMUCTXEvent IOMMUCTXEvent;
> > > @@ -50,6 +51,16 @@ union IOMMUCTXPASIDReqDesc {
> > >  };
> > >  typedef union IOMMUCTXPASIDReqDesc IOMMUCTXPASIDReqDesc;
> > >
> > > +struct IOMMUCTXPASIDBindData {
> > > +#define IOMMU_CTX_BIND_PASID   (1 << 0)
> > > +#define IOMMU_CTX_UNBIND_PASID (1 << 1)
> > > +    uint32_t flag;
> > > +#ifdef __linux__
> > > +    struct iommu_gpasid_bind_data *data;
> > 
> > Embedding a linux specific structure in the notification message seems
> > dubious to me.
> 
> Just similar as your above comment in this thread. If we don't want to add
> it there, then here it is also unnecessary.

... I'm not sure but maybe we need this here because I _think_ vt-d
should even work on Windows.  However instead of __linux__ over *data,
should you cover the whole IOMMUCTXPASIDBindData?

-- 
Peter Xu