> From: Liu, Yi L [mailto:yi.l.liu@xxxxxxxxxxxxxxx] > Sent: Sunday, May 14, 2017 6:55 PM > > On Fri, May 12, 2017 at 03:58:43PM -0600, Alex Williamson wrote: > > On Wed, 26 Apr 2017 18:12:04 +0800 > > "Liu, Yi L" <yi.l.liu@xxxxxxxxx> wrote: > > > > > From: "Liu, Yi L" <yi.l.liu@xxxxxxxxxxxxxxx> > > > > > > This patch adds VFIO_IOMMU_TLB_INVALIDATE to propagate IOMMU > TLB > > > invalidate request from guest to host. > > > > > > In the case of SVM virtualization on VT-d, host IOMMU driver has > > > no knowledge of caching structure updates unless the guest > > > invalidation activities are passed down to the host. So a new > > > IOCTL is needed to propagate the guest cache invalidation through > > > VFIO. > > > > > > Signed-off-by: Liu, Yi L <yi.l.liu@xxxxxxxxxxxxxxx> > > > --- > > > include/uapi/linux/vfio.h | 9 +++++++++ > > > 1 file changed, 9 insertions(+) > > > > > > diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h > > > index 6b97987..50c51f8 100644 > > > --- a/include/uapi/linux/vfio.h > > > +++ b/include/uapi/linux/vfio.h > > > @@ -564,6 +564,15 @@ struct vfio_device_svm { > > > > > > #define VFIO_IOMMU_SVM_BIND_TASK _IO(VFIO_TYPE, VFIO_BASE + > 22) > > > > > > +/* For IOMMU TLB Invalidation Propagation */ > > > +struct vfio_iommu_tlb_invalidate { > > > + __u32 argsz; > > > + __u32 length; > > > + __u8 data[]; > > > +}; > > > + > > > +#define VFIO_IOMMU_TLB_INVALIDATE _IO(VFIO_TYPE, VFIO_BASE + > 23) > > > > I'm kind of wondering why this isn't just a new flag bit on > > vfio_device_svm, the data structure is so similar. Of course data > > needs to be fully specified in uapi. > > Hi Alex, > > For this part, it depends on using opaque structure or not. The following > link mentioned it in [Open] session. > > http://www.spinics.net/lists/kvm/msg148798.html > > If we pick the full opaque solution for iommu tlb invalidate propagation. > Then I may add a flag bit on vfio_device_svm and also add definition in > uapi as you suggested. > there is another benefit to keep it as a separate command. For now we only need to invalidate 1st level translation (GVA->GPA) for SVM, since 1st level page table is provided by guest while directly walked by IOMMU. It's possible some vendor may also choose to implement a nested 2nd level translation (e.g. GIOVA->GPA->HPA) then hardware can directly walk guest GIOVA page table thus explicit invalidation is also required. We'd better not to limit invalidation interface with svm structure. Thanks Kevin
