[RFC,15/21] xen/arm: vsmmuv3: Emulated SMMUv3 device tree node for dom0less

Commit Message

Rahul Singh Dec. 1, 2022, 4:02 p.m. UTC

XEN will create an Emulated SMMUv3 device tree node in the device tree
to enable the dom0less domains to discover the virtual SMMUv3 during
boot. Emulated SMMUv3 device tree node will only be created when cmdline
option vsmmuv3 is enabled.

Signed-off-by: Rahul Singh <[e-mail]>
---
 xen/arch/arm/domain_build.c           | 52 +++++++++++++++++++++++++++
 xen/include/public/device_tree_defs.h |  1 +
 2 files changed, 53 insertions(+)

Comments

Michal Orzel Dec. 2, 2022, 2:19 p.m. UTC | #1

Hi Rahul,

On 01/12/2022 17:02, Rahul Singh wrote:
> 
> 
> XEN will create an Emulated SMMUv3 device tree node in the device tree
> to enable the dom0less domains to discover the virtual SMMUv3 during
> boot. Emulated SMMUv3 device tree node will only be created when cmdline
> option vsmmuv3 is enabled.
I think you meant viommu option.

In any case, I think that you want to introduce a device-tree property for dom0less domU
e.g. string property viommu = "smmuv3" to control whether to add a virtual IOMMU node or not for a given domU.
You did exactly the same for xl created domUs so you should do the same for dom0less domUs.
Otherwise the behavior will be inconsistent and we will lack per-domain control over virtual IOMMU.

~Michal

Patch

diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
index b82121beb5..29f00b18ec 100644
--- a/xen/arch/arm/domain_build.c
+++ b/xen/arch/arm/domain_build.c
@@ -2322,6 +2322,49 @@  static int make_hwdom_viommu_node(const struct kernel_info *kinfo)
 }
 #endif
 
+#ifdef CONFIG_VIRTUAL_ARM_SMMU_V3
+static int __init make_vsmmuv3_node(const struct kernel_info *kinfo)
+{
+    int res;
+    char buf[24];
+    __be32 reg[GUEST_ROOT_ADDRESS_CELLS + GUEST_ROOT_SIZE_CELLS];
+    __be32 *cells;
+    void *fdt = kinfo->fdt;
+
+    snprintf(buf, sizeof(buf), "iommu@%llx", GUEST_VSMMUV3_BASE);
+
+    res = fdt_begin_node(fdt, buf);
+    if ( res )
+        return res;
+
+    res = fdt_property_string(fdt, "compatible", "arm,smmu-v3");
+    if ( res )
+        return res;
+
+    /* Create reg property */
+    cells = &reg[0];
+    dt_child_set_range(&cells, GUEST_ROOT_ADDRESS_CELLS, GUEST_ROOT_SIZE_CELLS,
+                       GUEST_VSMMUV3_BASE, GUEST_VSMMUV3_SIZE);
+    res = fdt_property(fdt, "reg", reg,
+                       (GUEST_ROOT_ADDRESS_CELLS +
+                       GUEST_ROOT_SIZE_CELLS) * sizeof(*reg));
+    if ( res )
+        return res;
+
+    res = fdt_property_cell(fdt, "phandle", GUEST_PHANDLE_VSMMUV3);
+    if ( res )
+        return res;
+
+    res = fdt_property_cell(fdt, "#iommu-cells", 1);
+    if ( res )
+        return res;
+
+    res = fdt_end_node(fdt);
+
+    return res;
+}
+#endif
+
 int __init map_irq_to_domain(struct domain *d, unsigned int irq,
                              bool need_mapping, const char *devname)
 {
@@ -3395,6 +3438,15 @@  static int __init prepare_dtb_domU(struct domain *d, struct kernel_info *kinfo)
             goto err;
     }
 
+#ifdef CONFIG_VIRTUAL_ARM_SMMU_V3
+    if ( is_viommu_enabled() )
+    {
+        ret = make_vsmmuv3_node(kinfo);
+        if ( ret )
+            goto err;
+    }
+#endif
+
     ret = fdt_end_node(kinfo->fdt);
     if ( ret < 0 )
         goto err;
diff --git a/xen/include/public/device_tree_defs.h b/xen/include/public/device_tree_defs.h
index 9e80d0499d..7846a0425c 100644
--- a/xen/include/public/device_tree_defs.h
+++ b/xen/include/public/device_tree_defs.h
@@ -14,6 +14,7 @@ 
  */
 #define GUEST_PHANDLE_GIC (65000)
 #define GUEST_PHANDLE_IOMMU (GUEST_PHANDLE_GIC + 1)
+#define GUEST_PHANDLE_VSMMUV3 (GUEST_PHANDLE_IOMMU + 1)
 
 #define GUEST_ROOT_ADDRESS_CELLS 2
 #define GUEST_ROOT_SIZE_CELLS 2