[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [XEN PATCH v3] xen/arm: introduce dummy iommu node for dom0
On Tue, 11 Jan 2022, Sergiy Kibrik wrote: > Currently no IOMMU properties are exposed to dom0, thus kernel by default > assumes no protection and enables swiotlb-xen, which leads to costly and > unnecessary buffers bouncing. > > To let kernel know which device is behing IOMMU and hence needs no swiotlb > services we introduce dummy xen-iommu node in FDT and link protected device > nodes to it, using here device tree iommu bindings. > > Signed-off-by: Sergiy Kibrik <Sergiy_Kibrik@xxxxxxxx> I think the patch looks good. I have no further comments on the code: Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx> Before committing it to the Xen tree, I'd like to wait that the Linux side, especially the change to Documentation/devicetree/bindings/arm/xen.txt, is acked. > --- > Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx> > Cc: Julien Grall <julien@xxxxxxx> > Cc: Oleksandr Tyshchenko <olekstysh@xxxxxxxxx> > Cc: Andrii Anisov <Andrii_Anisov@xxxxxxxx> > > > Changelog: > > v3: rebased over staging & remove redundand phandle_iommu attribute, > discussion: > > https://lists.xenproject.org/archives/html/xen-devel/2021-12/msg01753.html > > v2: re-use common iommu dt bindings to let guests know which devices are > protected: > > https://lists.xenproject.org/archives/html/xen-devel/2021-10/msg00073.html > > xen/arch/arm/domain_build.c | 42 +++++++++++++++++++++++++++ > xen/include/public/device_tree_defs.h | 1 + > 2 files changed, 43 insertions(+) > > diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c > index 6931c022a2..b82ba72fac 100644 > --- a/xen/arch/arm/domain_build.c > +++ b/xen/arch/arm/domain_build.c > @@ -845,6 +845,12 @@ static int __init write_properties(struct domain *d, > struct kernel_info *kinfo, > } > } > > + if ( iommu_node && is_iommu_enabled(d) && dt_device_is_protected(node) ) > + { > + res = fdt_property_cell(kinfo->fdt, "iommus", GUEST_PHANDLE_IOMMU); > + if ( res ) > + return res; > + } > return 0; > } > > @@ -1479,6 +1485,38 @@ static int __init make_cpus_node(const struct domain > *d, void *fdt) > return res; > } > > +static int __init make_iommu_node(const struct domain *d, > + const struct kernel_info *kinfo) > +{ > + const char compat[] = "xen,iommu-el2-v1"; > + int res; > + > + if ( !is_iommu_enabled(d) ) > + return 0; > + > + dt_dprintk("Create iommu node\n"); > + > + res = fdt_begin_node(kinfo->fdt, "xen-iommu"); > + if ( res ) > + return res; > + > + res = fdt_property(kinfo->fdt, "compatible", compat, sizeof(compat)); > + if ( res ) > + return res; > + > + res = fdt_property_cell(kinfo->fdt, "#iommu-cells", 0); > + if ( res ) > + return res; > + > + res = fdt_property_cell(kinfo->fdt, "phandle", GUEST_PHANDLE_IOMMU); > + > + res = fdt_end_node(kinfo->fdt); > + if ( res ) > + return res; > + > + return res; > +} > + > static int __init make_gic_node(const struct domain *d, void *fdt, > const struct dt_device_node *node) > { > @@ -2127,6 +2165,10 @@ static int __init handle_node(struct domain *d, struct > kernel_info *kinfo, > if ( res ) > return res; > > + res = make_iommu_node(d, kinfo); > + if ( res ) > + return res; > + > res = make_memory_node(d, kinfo->fdt, addrcells, sizecells, > &kinfo->mem); > if ( res ) > return res; > diff --git a/xen/include/public/device_tree_defs.h > b/xen/include/public/device_tree_defs.h > index 209d43de3f..df58944bd0 100644 > --- a/xen/include/public/device_tree_defs.h > +++ b/xen/include/public/device_tree_defs.h > @@ -7,6 +7,7 @@ > * onwards. Reserve a high value for the GIC phandle. > */ > #define GUEST_PHANDLE_GIC (65000) > +#define GUEST_PHANDLE_IOMMU (GUEST_PHANDLE_GIC + 1) > > #define GUEST_ROOT_ADDRESS_CELLS 2 > #define GUEST_ROOT_SIZE_CELLS 2 > -- > 2.25.1 >
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