| Message ID | 20211222131847.2476835-2-Sergiy_Kibrik@epam.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [XEN,1/1] xen/arm: introduce dummy iommu node for dom0 | expand |
On Wed, 22 Dec 2021, 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@epam.com> Hi Sergiy, Thanks for the patch, I like how simple it is. FYI the patch doesn't apply cleanly to staging any longer, you might need to rebase it. > --- > xen/arch/arm/domain_build.c | 44 +++++++++++++++++++++++++++ > xen/include/asm-arm/kernel.h | 3 ++ > xen/include/public/device_tree_defs.h | 1 + > 3 files changed, 48 insertions(+) > > diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c > index 6cfc772e66..951ca0a0cb 100644 > --- a/xen/arch/arm/domain_build.c > +++ b/xen/arch/arm/domain_build.c > @@ -623,6 +623,12 @@ static int __init write_properties(struct domain *d, struct kernel_info *kinfo, > } > } > > + if ( iommu_node && kinfo->phandle_iommu && dt_device_is_protected(node) ) > + { > + res = fdt_property_cell(kinfo->fdt, "iommus", kinfo->phandle_iommu); > + if ( res ) > + return res; > + } > return 0; > } > > @@ -948,6 +954,38 @@ 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 ( !kinfo->phandle_iommu ) > + 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", kinfo->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) > { > @@ -1584,6 +1622,10 @@ 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; > @@ -2177,6 +2219,8 @@ static int __init prepare_dtb_hwdom(struct domain *d, struct kernel_info *kinfo) > ASSERT(dt_host && (dt_host->sibling == NULL)); > > kinfo->phandle_gic = dt_interrupt_controller->phandle; > + if ( is_iommu_enabled(d) ) > + kinfo->phandle_iommu = GUEST_PHANDLE_IOMMU; It doesn't look like we need to save GUEST_PHANDLE_IOMMU under kinfo. GUEST_PHANDLE_IOMMU is static. Instead we can just: if ( !is_iommu_enabled(d) ) return 0; at the beginning of make_iommu_node. Same for write_properties, we can just skip the kinfo->phandle_iommu check and use GUEST_PHANDLE_IOMMU in fdt_property_cell. > fdt = device_tree_flattened; > > new_size = fdt_totalsize(fdt) + DOM0_FDT_EXTRA_SIZE; > diff --git a/xen/include/asm-arm/kernel.h b/xen/include/asm-arm/kernel.h > index 874aa108a7..efe09cd1e0 100644 > --- a/xen/include/asm-arm/kernel.h > +++ b/xen/include/asm-arm/kernel.h > @@ -39,6 +39,9 @@ struct kernel_info { > /* GIC phandle */ > uint32_t phandle_gic; > > + /* dummy iommu phandle */ > + uint32_t phandle_iommu; > + > /* loader to use for this kernel */ > void (*load)(struct kernel_info *info); > /* loader specific state */ > 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 > >
diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c index 6cfc772e66..951ca0a0cb 100644 --- a/xen/arch/arm/domain_build.c +++ b/xen/arch/arm/domain_build.c @@ -623,6 +623,12 @@ static int __init write_properties(struct domain *d, struct kernel_info *kinfo, } } + if ( iommu_node && kinfo->phandle_iommu && dt_device_is_protected(node) ) + { + res = fdt_property_cell(kinfo->fdt, "iommus", kinfo->phandle_iommu); + if ( res ) + return res; + } return 0; } @@ -948,6 +954,38 @@ 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 ( !kinfo->phandle_iommu ) + 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", kinfo->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) { @@ -1584,6 +1622,10 @@ 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; @@ -2177,6 +2219,8 @@ static int __init prepare_dtb_hwdom(struct domain *d, struct kernel_info *kinfo) ASSERT(dt_host && (dt_host->sibling == NULL)); kinfo->phandle_gic = dt_interrupt_controller->phandle; + if ( is_iommu_enabled(d) ) + kinfo->phandle_iommu = GUEST_PHANDLE_IOMMU; fdt = device_tree_flattened; new_size = fdt_totalsize(fdt) + DOM0_FDT_EXTRA_SIZE; diff --git a/xen/include/asm-arm/kernel.h b/xen/include/asm-arm/kernel.h index 874aa108a7..efe09cd1e0 100644 --- a/xen/include/asm-arm/kernel.h +++ b/xen/include/asm-arm/kernel.h @@ -39,6 +39,9 @@ struct kernel_info { /* GIC phandle */ uint32_t phandle_gic; + /* dummy iommu phandle */ + uint32_t phandle_iommu; + /* loader to use for this kernel */ void (*load)(struct kernel_info *info); /* loader specific state */ 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
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@epam.com> --- xen/arch/arm/domain_build.c | 44 +++++++++++++++++++++++++++ xen/include/asm-arm/kernel.h | 3 ++ xen/include/public/device_tree_defs.h | 1 + 3 files changed, 48 insertions(+)