Re: [Qemu-devel] [PATCH RFC v4 16/20] intel_iommu: do replay when context invalidate

[Tian, Kevin]

> From: Peter Xu [mailto:address@hidden
> Sent: Wednesday, January 25, 2017 11:46 AM
> 
> On Wed, Jan 25, 2017 at 11:09:39AM +0800, Jason Wang wrote:
> >
> >
> > On 2017年01月24日 12:52, Peter Xu wrote:
> > >On Mon, Jan 23, 2017 at 06:36:17PM +0800, Jason Wang wrote:
> > >>
> > >>On 2017年01月20日 21:08, Peter Xu wrote:
> > >>>Before this one we only invalidate context cache when we receive context
> > >>>entry invalidations. However it's possible that the invalidation also
> > >>>contains a domain switch (only if cache-mode is enabled for vIOMMU). In
> > >>>that case we need to notify all the registered components about the new
> > >>>mapping.
> > >>>
> > >>>Signed-off-by: Peter Xu <address@hidden>
> > >>>---
> > >>>  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 f9c5142..4b08b4d 100644
> > >>>--- a/hw/i386/intel_iommu.c
> > >>>+++ b/hw/i386/intel_iommu.c
> > >>>@@ -1146,6 +1146,16 @@ static void
> vtd_context_device_invalidate(IntelIOMMUState *s,
> > >>>                  trace_vtd_inv_desc_cc_device(bus_n, 
> > >>> VTD_PCI_SLOT(devfn_it),
> > >>>                                               VTD_PCI_FUNC(devfn_it));
> > >>>                  vtd_as->context_cache_entry.context_cache_gen = 0;
> > >>>+                /*
> > >>>+                 * So a device is moving out of (or moving into) a
> > >>>+                 * domain, a replay() suites here to notify all the
> > >>>+                 * IOMMU_NOTIFIER_MAP registers about this change.
> > >>>+                 * This won't bring bad even if we have no such
> > >>>+                 * notifier registered - the IOMMU notification
> > >>>+                 * framework will skip MAP notifications if that
> > >>>+                 * happened.
> > >>>+                 */
> > >>>+                memory_region_iommu_replay_all(&vtd_as->iommu);
> > >>DSI and GLOBAL questions come back again or no need to care about them :) 
> > >>?
> > >DSI/GLOBAL hanldings are in patch 20 (though it'll be squashed into 18
> > >in my next post). Is that what you mean above?
> >
> > Seems not, I mean DSI/GLOBAL for context cache invalidation instead of IOTLB
> > :)
> 
> Yes, I should possibly do the same thing for context cache global
> invalidations. IIUC context global invalidation should be a superset
> of iotlb invalidation, so maybe I'll add one more patch to call iotlb
> invalidation in context invalidation as well. Kevin/others, please
> correct me if I misunderstood the spec. Thanks,
> 

context invalidation is not superset of iotlb invalidation. The spec just
requires software to always follow a context-cache invalidation with
a PASID-cache invalidation, followed by an IOTLB invalidation.

Thanks
Kevin