| Message ID | 20211222131847.2476835-3-Sergiy_Kibrik@epam.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [1/1] arm/xen: don't use xen DMA ops when the device is protected by an IOMMU | expand |
On Wed, 22 Dec 2021, Sergiy Kibrik wrote: > Only Xen is able to know if a device can safely avoid to use xen-swiotlb. > However since Xen links FDT nodes of protected devices to special dummy > xen-iommu node we can use that information to decide whether > xen-swiotlb is needed. > > Signed-off-by: Sergiy Kibrik <Sergiy_Kibrik@epam.com> > --- > arch/arm/mm/dma-mapping.c | 2 +- > arch/arm/xen/enlighten.c | 9 +++++++++ > arch/arm64/mm/dma-mapping.c | 2 +- > include/xen/swiotlb-xen.h | 1 + > 4 files changed, 12 insertions(+), 2 deletions(-) > > diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c > index c4b8df2ad328..fc875dd16e0e 100644 > --- a/arch/arm/mm/dma-mapping.c > +++ b/arch/arm/mm/dma-mapping.c > @@ -2280,7 +2280,7 @@ void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size, > set_dma_ops(dev, dma_ops); > > #ifdef CONFIG_XEN > - if (xen_initial_domain()) > + if (xen_initial_domain() && !xen_is_protected_device(dev)) > dev->dma_ops = &xen_swiotlb_dma_ops; > #endif > dev->archdata.dma_ops_setup = true; > diff --git a/arch/arm/xen/enlighten.c b/arch/arm/xen/enlighten.c > index 49f566ad9acb..b36659238db3 100644 > --- a/arch/arm/xen/enlighten.c > +++ b/arch/arm/xen/enlighten.c > @@ -66,6 +66,15 @@ static __read_mostly unsigned int xen_events_irq; > uint32_t xen_start_flags; > EXPORT_SYMBOL(xen_start_flags); > > +bool xen_is_protected_device(struct device *dev) > +{ > + struct fwnode_handle *fwnode = > + fwnode_find_reference(dev_fwnode(dev), "iommus", 0) ; > + if (IS_ERR(fwnode)) > + return false; > + return of_device_is_compatible(to_of_node(fwnode), "xen,iommu-el2-v1"); > +} We need to add a description of the "xen,iommu-el2-v1" compatible node under Documentation/devicetree/bindings. Maybe it could be added to Documentation/devicetree/bindings/arm/xen.txt, but it could also be its own new file. > int xen_unmap_domain_gfn_range(struct vm_area_struct *vma, > int nr, struct page **pages) > { > diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c > index 93e87b287556..68248e72e052 100644 > --- a/arch/arm64/mm/dma-mapping.c > +++ b/arch/arm64/mm/dma-mapping.c > @@ -53,7 +53,7 @@ void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size, > iommu_setup_dma_ops(dev, dma_base, size); > > #ifdef CONFIG_XEN > - if (xen_initial_domain()) > + if (xen_initial_domain() && !xen_is_protected_device(dev)) > dev->dma_ops = &xen_swiotlb_dma_ops; This patch needs to be rebased on the latest master. You'll see that now we have a more sophisticated xen_swiotlb_detect(), instead of the simple xen_initial_domain() we used to have. Still, xen_swiotlb_detect() is global, not per device, so I think this change would still apply as is, resulting in: if (xen_swiotlb_detect() && !xen_is_protected_device(dev)) dev->dma_ops = &xen_swiotlb_dma_ops; > #endif > } > diff --git a/include/xen/swiotlb-xen.h b/include/xen/swiotlb-xen.h > index d5eaf9d682b8..00b2782430fb 100644 > --- a/include/xen/swiotlb-xen.h > +++ b/include/xen/swiotlb-xen.h > @@ -8,6 +8,7 @@ void xen_dma_sync_for_cpu(struct device *dev, dma_addr_t handle, > size_t size, enum dma_data_direction dir); > void xen_dma_sync_for_device(struct device *dev, dma_addr_t handle, > size_t size, enum dma_data_direction dir); > +bool xen_is_protected_device(struct device *dev); > > extern int xen_swiotlb_init(int verbose, bool early); > extern const struct dma_map_ops xen_swiotlb_dma_ops;
diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c index c4b8df2ad328..fc875dd16e0e 100644 --- a/arch/arm/mm/dma-mapping.c +++ b/arch/arm/mm/dma-mapping.c @@ -2280,7 +2280,7 @@ void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size, set_dma_ops(dev, dma_ops); #ifdef CONFIG_XEN - if (xen_initial_domain()) + if (xen_initial_domain() && !xen_is_protected_device(dev)) dev->dma_ops = &xen_swiotlb_dma_ops; #endif dev->archdata.dma_ops_setup = true; diff --git a/arch/arm/xen/enlighten.c b/arch/arm/xen/enlighten.c index 49f566ad9acb..b36659238db3 100644 --- a/arch/arm/xen/enlighten.c +++ b/arch/arm/xen/enlighten.c @@ -66,6 +66,15 @@ static __read_mostly unsigned int xen_events_irq; uint32_t xen_start_flags; EXPORT_SYMBOL(xen_start_flags); +bool xen_is_protected_device(struct device *dev) +{ + struct fwnode_handle *fwnode = + fwnode_find_reference(dev_fwnode(dev), "iommus", 0) ; + if (IS_ERR(fwnode)) + return false; + return of_device_is_compatible(to_of_node(fwnode), "xen,iommu-el2-v1"); +} + int xen_unmap_domain_gfn_range(struct vm_area_struct *vma, int nr, struct page **pages) { diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c index 93e87b287556..68248e72e052 100644 --- a/arch/arm64/mm/dma-mapping.c +++ b/arch/arm64/mm/dma-mapping.c @@ -53,7 +53,7 @@ void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size, iommu_setup_dma_ops(dev, dma_base, size); #ifdef CONFIG_XEN - if (xen_initial_domain()) + if (xen_initial_domain() && !xen_is_protected_device(dev)) dev->dma_ops = &xen_swiotlb_dma_ops; #endif } diff --git a/include/xen/swiotlb-xen.h b/include/xen/swiotlb-xen.h index d5eaf9d682b8..00b2782430fb 100644 --- a/include/xen/swiotlb-xen.h +++ b/include/xen/swiotlb-xen.h @@ -8,6 +8,7 @@ void xen_dma_sync_for_cpu(struct device *dev, dma_addr_t handle, size_t size, enum dma_data_direction dir); void xen_dma_sync_for_device(struct device *dev, dma_addr_t handle, size_t size, enum dma_data_direction dir); +bool xen_is_protected_device(struct device *dev); extern int xen_swiotlb_init(int verbose, bool early); extern const struct dma_map_ops xen_swiotlb_dma_ops;
Only Xen is able to know if a device can safely avoid to use xen-swiotlb. However since Xen links FDT nodes of protected devices to special dummy xen-iommu node we can use that information to decide whether xen-swiotlb is needed. Signed-off-by: Sergiy Kibrik <Sergiy_Kibrik@epam.com> --- arch/arm/mm/dma-mapping.c | 2 +- arch/arm/xen/enlighten.c | 9 +++++++++ arch/arm64/mm/dma-mapping.c | 2 +- include/xen/swiotlb-xen.h | 1 + 4 files changed, 12 insertions(+), 2 deletions(-)