Re: [Qemu-devel] [PATCH v4 RESEND 0/3] IOMMU: intel_iommu support map and unmap notifications

[Aviv B.D.]

On Mon, Oct 17, 2016 at 7:07 PM, Alex Williamson <address@hidden
> wrote:

> On Mon, 17 Oct 2016 18:44:21 +0300
> "Aviv B.D" <address@hidden> wrote:
>
> > From: "Aviv Ben-David" <address@hidden>
> >
> > * Advertize Cache Mode capability in iommu cap register.
> >   This capability is controlled by "cache-mode" property of intel-iommu
> device.
> >   To enable this option call QEMU with "-device
> intel-iommu,cache-mode=true".
> >
> > * On page cache invalidation in intel vIOMMU, check if the domain belong
> to
> >   registered notifier, and notify accordingly.
> >
> > Currently this patch still doesn't enabling VFIO devices support with
> vIOMMU
> > present. Current problems:
> > * vfio_iommu_map_notify is not aware about memory range belong to
> specific
> >   VFIOGuestIOMMU.
>
> Could you elaborate on why this is an issue?
>

In my setup the VFIO registered two memory areas with one page of
unregistered memory
between them.

When I'm calling memory_region_notify_iommu it calls the notifier function
of VFIO twice
when the second time is failing with warning to console as the new mapping
is already present.

The notifier function of VFIO should ignore IOMMUTLBEntry that is not in
the correct
range.


>
> > * memory_region_iommu_replay hangs QEMU on start up while it itterate
> over
> >   64bit address space. Commenting out the call to this function enables
> >   workable VFIO device while vIOMMU present.
>
> This has been discussed previously, it would be incorrect for vfio not
> to call the replay function.  The solution is to add an iommu driver
> callback to efficiently walk the mappings within a MemoryRegion.
> Thanks,
>

I'm aware about those discussion, I put this info here as helpful reminder
if someone wants to
test my code.


> Alex
>
> > Changes from v1 to v2:
> > * remove assumption that the cache do not clears
> > * fix lockup on high load.
> >
> > Changes from v2 to v3:
> > * remove debug leftovers
> > * split to sepearate commits
> > * change is_write to flags in vtd_do_iommu_translate, add IOMMU_NO_FAIL
> >   to suppress error propagating to guest.
> >
> > Changes from v3 to v4:
> > * Add property to intel_iommu device to control the CM capability,
> >   default to False.
> > * Use s->iommu_ops.notify_flag_changed to register notifiers.
> >
> > Changes from v4 to v4 RESEND:
> > * Fix codding style pointed by checkpatch.pl script.
> >
> > Aviv Ben-David (3):
> >   IOMMU: add option to enable VTD_CAP_CM to vIOMMU capility exposoed to
> >     guest
> >   IOMMU: change iommu_op->translate's is_write to flags, add support to
> >     NO_FAIL flag mode
> >   IOMMU: enable intel_iommu map and unmap notifiers
> >
> >  exec.c                         |   3 +-
> >  hw/i386/amd_iommu.c            |   4 +-
> >  hw/i386/intel_iommu.c          | 175 ++++++++++++++++++++++++++++++
> +++--------
> >  hw/i386/intel_iommu_internal.h |   3 +
> >  include/exec/memory.h          |   6 +-
> >  include/hw/i386/intel_iommu.h  |  11 +++
> >  memory.c                       |   3 +-
> >  7 files changed, 168 insertions(+), 37 deletions(-)
> >
>
>
Aviv.