Messages in this thread | | | Subject | Re: [PATCH v7 06/23] iommu: Introduce bind/unbind_guest_msi | From | Robin Murphy <> | Date | Wed, 8 May 2019 14:59:38 +0100 |
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On 08/04/2019 13:18, Eric Auger wrote: > On ARM, MSI are translated by the SMMU. An IOVA is allocated > for each MSI doorbell. If both the host and the guest are exposed > with SMMUs, we end up with 2 different IOVAs allocated by each. > guest allocates an IOVA (gIOVA) to map onto the guest MSI > doorbell (gDB). The Host allocates another IOVA (hIOVA) to map > onto the physical doorbell (hDB). > > So we end up with 2 untied mappings: > S1 S2 > gIOVA -> gDB > hIOVA -> hDB > > Currently the PCI device is programmed by the host with hIOVA > as MSI doorbell. So this does not work. > > This patch introduces an API to pass gIOVA/gDB to the host so > that gIOVA can be reused by the host instead of re-allocating > a new IOVA. So the goal is to create the following nested mapping: > > S1 S2 > gIOVA -> gDB -> hDB > > and program the PCI device with gIOVA MSI doorbell. > > In case we have several devices attached to this nested domain > (devices belonging to the same group), they cannot be isolated > on guest side either. So they should also end up in the same domain > on guest side. We will enforce that all the devices attached to > the host iommu domain use the same physical doorbell and similarly > a single virtual doorbell mapping gets registered (1 single > virtual doorbell is used on guest as well). > > Signed-off-by: Eric Auger <eric.auger@redhat.com> > > --- > v6 -> v7: > - remove the device handle parameter. > - Add comments saying there can only be a single MSI binding > registered per iommu_domain > v5 -> v6: > -fix compile issue when IOMMU_API is not set > > v3 -> v4: > - add unbind > > v2 -> v3: > - add a struct device handle > --- > drivers/iommu/iommu.c | 37 +++++++++++++++++++++++++++++++++++++ > include/linux/iommu.h | 23 +++++++++++++++++++++++ > 2 files changed, 60 insertions(+) > > diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c > index 6d6cb4005ca5..0d160bbd6f81 100644 > --- a/drivers/iommu/iommu.c > +++ b/drivers/iommu/iommu.c > @@ -1575,6 +1575,43 @@ static void __iommu_detach_device(struct iommu_domain *domain, > trace_detach_device_from_domain(dev); > } > > +/** > + * iommu_bind_guest_msi - Passes the stage1 GIOVA/GPA mapping of a > + * virtual doorbell > + * > + * @domain: iommu domain the stage 1 mapping will be attached to > + * @iova: iova allocated by the guest > + * @gpa: guest physical address of the virtual doorbell > + * @size: granule size used for the mapping > + * > + * The associated IOVA can be reused by the host to create a nested > + * stage2 binding mapping translating into the physical doorbell used > + * by the devices attached to the domain. > + * > + * All devices within the domain must share the same physical doorbell. > + * A single MSI GIOVA/GPA mapping can be attached to an iommu_domain. > + */ > + > +int iommu_bind_guest_msi(struct iommu_domain *domain, > + dma_addr_t giova, phys_addr_t gpa, size_t size) > +{ > + if (unlikely(!domain->ops->bind_guest_msi)) > + return -ENODEV; > + > + return domain->ops->bind_guest_msi(domain, giova, gpa, size); > +} > +EXPORT_SYMBOL_GPL(iommu_bind_guest_msi); > + > +void iommu_unbind_guest_msi(struct iommu_domain *domain, > + dma_addr_t iova) > +{ > + if (unlikely(!domain->ops->unbind_guest_msi)) > + return; > + > + domain->ops->unbind_guest_msi(domain, iova); > +} > +EXPORT_SYMBOL_GPL(iommu_unbind_guest_msi); > + > void iommu_detach_device(struct iommu_domain *domain, struct device *dev) > { > struct iommu_group *group; > diff --git a/include/linux/iommu.h b/include/linux/iommu.h > index 7c7c6bad1420..a2f3f964ead2 100644 > --- a/include/linux/iommu.h > +++ b/include/linux/iommu.h > @@ -192,6 +192,8 @@ struct iommu_resv_region { > * @attach_pasid_table: attach a pasid table > * @detach_pasid_table: detach the pasid table > * @cache_invalidate: invalidate translation caches > + * @bind_guest_msi: provides a stage1 giova/gpa MSI doorbell mapping > + * @unbind_guest_msi: withdraw a stage1 giova/gpa MSI doorbell mapping > * @pgsize_bitmap: bitmap of all possible supported page sizes > */ > struct iommu_ops { > @@ -243,6 +245,10 @@ struct iommu_ops { > int (*cache_invalidate)(struct iommu_domain *domain, struct device *dev, > struct iommu_cache_invalidate_info *inv_info); > > + int (*bind_guest_msi)(struct iommu_domain *domain, > + dma_addr_t giova, phys_addr_t gpa, size_t size); > + void (*unbind_guest_msi)(struct iommu_domain *domain, dma_addr_t giova); > + > unsigned long pgsize_bitmap; > }; > > @@ -356,6 +362,11 @@ extern void iommu_detach_pasid_table(struct iommu_domain *domain); > extern int iommu_cache_invalidate(struct iommu_domain *domain, > struct device *dev, > struct iommu_cache_invalidate_info *inv_info); > +extern int iommu_bind_guest_msi(struct iommu_domain *domain, > + dma_addr_t giova, phys_addr_t gpa, size_t size); > +extern void iommu_unbind_guest_msi(struct iommu_domain *domain, > + dma_addr_t giova); > + > extern struct iommu_domain *iommu_get_domain_for_dev(struct device *dev); > extern struct iommu_domain *iommu_get_dma_domain(struct device *dev); > extern int iommu_map(struct iommu_domain *domain, unsigned long iova, > @@ -812,6 +823,18 @@ iommu_cache_invalidate(struct iommu_domain *domain, > return -ENODEV; > } > > +static inline > +int iommu_bind_guest_msi(struct iommu_domain *domain, > + dma_addr_t giova, phys_addr_t gpa, size_t size) > +{ > + return -ENODEV; > +} > +static inline > +int iommu_unbind_guest_msi(struct iommu_domain *domain, dma_addr_t giova) > +{ > + return -ENODEV;
It's less of a problem than mismatching the other way round, but for consistency this should return void like the real version.
Robin.
> +} > + > #endif /* CONFIG_IOMMU_API */ > > #ifdef CONFIG_IOMMU_DEBUGFS >
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