Jean-Philippe Brucker
2022-Jul-14 11:11 UTC
[PATCH] iommu/virtio: Advertise IOMMU_CAP_CACHE_COHERENCY
Fix virtio-iommu interaction with VFIO, as VFIO now requires
IOMMU_CAP_CACHE_COHERENCY. virtio-iommu does not support non-cacheable
mappings, and always expects to be called with IOMMU_CACHE.
Fixes: e8ae0e140c05 ("vfio: Require that devices support DMA cache
coherence")
Signed-off-by: Jean-Philippe Brucker <jean-philippe at linaro.org>
---
drivers/iommu/virtio-iommu.c | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/drivers/iommu/virtio-iommu.c b/drivers/iommu/virtio-iommu.c
index 25be4b822aa0..bf340d779c10 100644
--- a/drivers/iommu/virtio-iommu.c
+++ b/drivers/iommu/virtio-iommu.c
@@ -1006,7 +1006,18 @@ static int viommu_of_xlate(struct device *dev, struct
of_phandle_args *args)
return iommu_fwspec_add_ids(dev, args->args, 1);
}
+static bool viommu_capable(enum iommu_cap cap)
+{
+ switch (cap) {
+ case IOMMU_CAP_CACHE_COHERENCY:
+ return true;
+ default:
+ return false;
+ }
+}
+
static struct iommu_ops viommu_ops = {
+ .capable = viommu_capable,
.domain_alloc = viommu_domain_alloc,
.probe_device = viommu_probe_device,
.probe_finalize = viommu_probe_finalize,
--
2.36.1
Robin Murphy
2022-Jul-14 12:01 UTC
[PATCH] iommu/virtio: Advertise IOMMU_CAP_CACHE_COHERENCY
On 2022-07-14 12:11, Jean-Philippe Brucker wrote:> Fix virtio-iommu interaction with VFIO, as VFIO now requires > IOMMU_CAP_CACHE_COHERENCY. virtio-iommu does not support non-cacheable > mappings, and always expects to be called with IOMMU_CACHE.Can we know this is actually true though? What if the virtio-iommu implementation is backed by something other than VFIO, and the underlying hardware isn't coherent? AFAICS the spec doesn't disallow that. Thanks, Robin.> Fixes: e8ae0e140c05 ("vfio: Require that devices support DMA cache coherence") > Signed-off-by: Jean-Philippe Brucker <jean-philippe at linaro.org> > --- > drivers/iommu/virtio-iommu.c | 11 +++++++++++ > 1 file changed, 11 insertions(+) > > diff --git a/drivers/iommu/virtio-iommu.c b/drivers/iommu/virtio-iommu.c > index 25be4b822aa0..bf340d779c10 100644 > --- a/drivers/iommu/virtio-iommu.c > +++ b/drivers/iommu/virtio-iommu.c > @@ -1006,7 +1006,18 @@ static int viommu_of_xlate(struct device *dev, struct of_phandle_args *args) > return iommu_fwspec_add_ids(dev, args->args, 1); > } > > +static bool viommu_capable(enum iommu_cap cap) > +{ > + switch (cap) { > + case IOMMU_CAP_CACHE_COHERENCY: > + return true; > + default: > + return false; > + } > +} > + > static struct iommu_ops viommu_ops = { > + .capable = viommu_capable, > .domain_alloc = viommu_domain_alloc, > .probe_device = viommu_probe_device, > .probe_finalize = viommu_probe_finalize,