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* [PATCH v8 15/24] hw/arm: virt: cleanly fail on attempt to use the platform vGIC together with ITS
@ 2025-10-16 18:44 Mohamed Mediouni
  2025-10-16 18:44 ` [PATCH v8 16/24] docs: arm: update virt machine model description Mohamed Mediouni
                   ` (8 more replies)
  0 siblings, 9 replies; 10+ messages in thread
From: Mohamed Mediouni @ 2025-10-16 18:44 UTC (permalink / raw)
  To: qemu-devel
  Cc: qemu-arm, Philippe Mathieu-Daudé, Paolo Bonzini,
	Peter Maydell, Phil Dennis-Jordan, Cameron Esfahani,
	Alexander Graf, Mohamed Mediouni, Mads Ynddal, Pedro Barbuda

Switch its to a tristate.

Windows Hypervisor Platform's vGIC doesn't support ITS.
Deal with this by reporting to the user and exiting.

Regular configuration: GICv3 + ITS
New default configuration with WHPX: GICv3 with GICv2m
And its=off explicitly for the newest machine version: GICv3 + GICv2m

Signed-off-by: Mohamed Mediouni <mohamed@unpredictable.fr>
---
 hw/arm/virt-acpi-build.c | 15 +++++++------
 hw/arm/virt.c            | 46 +++++++++++++++++++++++++++++++---------
 include/hw/arm/virt.h    |  4 +++-
 3 files changed, 47 insertions(+), 18 deletions(-)

diff --git a/hw/arm/virt-acpi-build.c b/hw/arm/virt-acpi-build.c
index 0a6ec74aa0..8e730731ca 100644
--- a/hw/arm/virt-acpi-build.c
+++ b/hw/arm/virt-acpi-build.c
@@ -472,7 +472,7 @@ build_iort(GArray *table_data, BIOSLinker *linker, VirtMachineState *vms)
         nb_nodes = num_smmus + 1; /* RC and SMMUv3 */
         rc_mapping_count = rc_smmu_idmaps_len;
 
-        if (vms->its) {
+        if (virt_is_its_enabled(vms)) {
             /*
              * Knowing the ID ranges from the RC to the SMMU, it's possible to
              * determine the ID ranges from RC that go directly to ITS.
@@ -483,7 +483,7 @@ build_iort(GArray *table_data, BIOSLinker *linker, VirtMachineState *vms)
             rc_mapping_count += rc_its_idmaps->len;
         }
     } else {
-        if (vms->its) {
+        if (virt_is_its_enabled(vms)) {
             nb_nodes = 2; /* RC and ITS */
             rc_mapping_count = 1; /* Direct map to ITS */
         } else {
@@ -498,7 +498,7 @@ build_iort(GArray *table_data, BIOSLinker *linker, VirtMachineState *vms)
     build_append_int_noprefix(table_data, IORT_NODE_OFFSET, 4);
     build_append_int_noprefix(table_data, 0, 4); /* Reserved */
 
-    if (vms->its) {
+    if (virt_is_its_enabled(vms)) {
         /* Table 12 ITS Group Format */
         build_append_int_noprefix(table_data, 0 /* ITS Group */, 1); /* Type */
         node_size =  20 /* fixed header size */ + 4 /* 1 GIC ITS Identifier */;
@@ -517,7 +517,7 @@ build_iort(GArray *table_data, BIOSLinker *linker, VirtMachineState *vms)
         int smmu_mapping_count, offset_to_id_array;
         int irq = sdev->irq;
 
-        if (vms->its) {
+        if (virt_is_its_enabled(vms)) {
             smmu_mapping_count = 1; /* ITS Group node */
             offset_to_id_array = SMMU_V3_ENTRY_SIZE; /* Just after the header */
         } else {
@@ -610,7 +610,7 @@ build_iort(GArray *table_data, BIOSLinker *linker, VirtMachineState *vms)
             }
         }
 
-        if (vms->its) {
+        if (virt_is_its_enabled(vms)) {
             /*
              * Map bypassed (don't go through the SMMU) RIDs (input) to
              * ITS Group node directly: RC -> ITS.
@@ -945,7 +945,7 @@ build_madt(GArray *table_data, BIOSLinker *linker, VirtMachineState *vms)
                                           memmap[VIRT_HIGH_GIC_REDIST2].size);
         }
 
-        if (vms->its) {
+        if (virt_is_its_enabled(vms)) {
             /*
              * ACPI spec, Revision 6.0 Errata A
              * (original 6.0 definition has invalid Length)
@@ -961,7 +961,8 @@ build_madt(GArray *table_data, BIOSLinker *linker, VirtMachineState *vms)
         }
     }
 
-    if (!(vms->gic_version != VIRT_GIC_VERSION_2 && vms->its) && !vms->no_gicv3_with_gicv2m) {
+    if (!(vms->gic_version != VIRT_GIC_VERSION_2 && virt_is_its_enabled(vms))
+     && !vms->no_gicv3_with_gicv2m) {
         const uint16_t spi_base = vms->irqmap[VIRT_GIC_V2M] + ARM_SPI_BASE;
 
         /* 5.2.12.16 GIC MSI Frame Structure */
diff --git a/hw/arm/virt.c b/hw/arm/virt.c
index 9121eb37eb..dbf9a28b8d 100644
--- a/hw/arm/virt.c
+++ b/hw/arm/virt.c
@@ -735,7 +735,7 @@ static void create_its(VirtMachineState *vms)
 {
     DeviceState *dev;
 
-    assert(vms->its);
+    assert(virt_is_its_enabled(vms));
     if (!kvm_irqchip_in_kernel() && !vms->tcg_its) {
         /*
          * Do nothing if ITS is neither supported by the host nor emulated by
@@ -744,6 +744,15 @@ static void create_its(VirtMachineState *vms)
         return;
     }
 
+    if (whpx_enabled() && vms->tcg_its) {
+        /*
+         * Signal to the user when ITS is neither supported by the host
+         * nor emulated by the machine.
+         */
+        info_report("ITS not supported on WHPX.");
+        exit(1);
+    }
+
     dev = qdev_new(its_class_name());
 
     object_property_set_link(OBJECT(dev), "parent-gicv3", OBJECT(vms->gic),
@@ -955,7 +964,7 @@ static void create_gic(VirtMachineState *vms, MemoryRegion *mem)
 
     fdt_add_gic_node(vms);
 
-    if (vms->gic_version != VIRT_GIC_VERSION_2 && vms->its) {
+    if (vms->gic_version != VIRT_GIC_VERSION_2 && virt_is_its_enabled(vms)) {
         create_its(vms);
     } else if (vms->gic_version != VIRT_GIC_VERSION_2 && !vms->no_gicv3_with_gicv2m) {
         create_v2m(vms);
@@ -2705,18 +2714,34 @@ static void virt_set_highmem_mmio_size(Object *obj, Visitor *v,
     extended_memmap[VIRT_HIGH_PCIE_MMIO].size = size;
 }
 
-static bool virt_get_its(Object *obj, Error **errp)
+bool virt_is_its_enabled(VirtMachineState *vms)
+{
+    if (vms->its == ON_OFF_AUTO_OFF) {
+        return false;
+    }
+    if (vms->its == ON_OFF_AUTO_AUTO) {
+        if (whpx_enabled()) {
+            return false;
+        }
+    }
+    return true;
+}
+
+static void virt_get_its(Object *obj, Visitor *v, const char *name,
+                          void *opaque, Error **errp)
 {
     VirtMachineState *vms = VIRT_MACHINE(obj);
+    OnOffAuto its = vms->its;
 
-    return vms->its;
+    visit_type_OnOffAuto(v, name, &its, errp);
 }
 
-static void virt_set_its(Object *obj, bool value, Error **errp)
+static void virt_set_its(Object *obj, Visitor *v, const char *name,
+                          void *opaque, Error **errp)
 {
     VirtMachineState *vms = VIRT_MACHINE(obj);
 
-    vms->its = value;
+    visit_type_OnOffAuto(v, name, &vms->its, errp);
 }
 
 static bool virt_get_dtb_randomness(Object *obj, Error **errp)
@@ -3426,8 +3451,9 @@ static void virt_machine_class_init(ObjectClass *oc, const void *data)
                                           "guest CPU which implements the ARM "
                                           "Memory Tagging Extension");
 
-    object_class_property_add_bool(oc, "its", virt_get_its,
-                                   virt_set_its);
+    object_class_property_add(oc, "its", "OnOffAuto",
+        virt_get_its, virt_set_its,
+        NULL, NULL);
     object_class_property_set_description(oc, "its",
                                           "Set on/off to enable/disable "
                                           "ITS instantiation");
@@ -3487,8 +3513,8 @@ static void virt_instance_init(Object *obj)
     vms->highmem_mmio = true;
     vms->highmem_redists = true;
 
-    /* Default allows ITS instantiation */
-    vms->its = true;
+    /* Default allows ITS instantiation if available */
+    vms->its = ON_OFF_AUTO_AUTO;
     /* Allow ITS emulation if the machine version supports it */
     vms->tcg_its = !vmc->no_tcg_its;
     vms->no_gicv3_with_gicv2m = false;
diff --git a/include/hw/arm/virt.h b/include/hw/arm/virt.h
index d31348dd61..997dd51678 100644
--- a/include/hw/arm/virt.h
+++ b/include/hw/arm/virt.h
@@ -149,7 +149,7 @@ struct VirtMachineState {
     bool highmem_ecam;
     bool highmem_mmio;
     bool highmem_redists;
-    bool its;
+    OnOffAuto its;
     bool tcg_its;
     bool virt;
     bool ras;
@@ -218,4 +218,6 @@ static inline int virt_gicv3_redist_region_count(VirtMachineState *vms)
             vms->highmem_redists) ? 2 : 1;
 }
 
+bool virt_is_its_enabled(VirtMachineState *vms);
+
 #endif /* QEMU_ARM_VIRT_H */
-- 
2.50.1 (Apple Git-155)



^ permalink raw reply related	[flat|nested] 10+ messages in thread
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Thread overview: 10+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2025-10-16 18:44 [PATCH v8 15/24] hw/arm: virt: cleanly fail on attempt to use the platform vGIC together with ITS Mohamed Mediouni
2025-10-16 18:44 ` [PATCH v8 16/24] docs: arm: update virt machine model description Mohamed Mediouni
2025-10-16 18:44 ` [PATCH v8 17/24] whpx: arm64: clamp down IPA size Mohamed Mediouni
2025-10-16 18:44 ` [PATCH v8 18/24] hw/arm, accel/hvf, whpx: unify get_physical_address_range between WHPX and HVF Mohamed Mediouni
2025-10-16 18:44 ` [PATCH v8 19/24] whpx: arm64: implement -cpu host Mohamed Mediouni
2025-10-16 18:44 ` [PATCH v8 20/24] target/arm: whpx: instantiate GIC early Mohamed Mediouni
2025-10-16 18:44 ` [PATCH v8 21/24] whpx: arm64: gicv3: add migration blocker Mohamed Mediouni
2025-10-16 18:44 ` [PATCH v8 22/24] whpx: enable arm64 builds Mohamed Mediouni
2025-10-16 18:44 ` [PATCH v8 23/24] MAINTAINERS: update maintainers for WHPX Mohamed Mediouni
2025-10-16 18:44 ` [PATCH v8 24/24] whpx: apic: use non-deprecated APIs to control interrupt controller state Mohamed Mediouni

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