[PATCH v2 5/5] KVM: arm64: selftests: Add GICv2 IGROUPR writability test
David Woodhouse
dwmw2 at infradead.org
Wed Apr 8 04:30:36 PDT 2026
From: David Woodhouse <dwmw at amazon.co.uk>
Test that GICv2 IGROUPR writability is consistently gated by the IIDR
implementation revision for both guest and userspace paths:
Default (no IIDR write): implementation_rev defaults to 3, groups
writable from both guest and userspace.
Rev 1: IGROUPR reads as zero (group 0), writes ignored from both
guest and userspace.
Rev 2: IGROUPR is writable from both guest and userspace.
This test requires GICv2 emulation support (GICv3 with GICv2 compat
CPU interface) and will be skipped on hardware without it.
Signed-off-by: David Woodhouse <dwmw at amazon.co.uk>
---
tools/testing/selftests/kvm/Makefile.kvm | 1 +
.../selftests/kvm/arm64/vgic_group_v2.c | 168 ++++++++++++++++++
2 files changed, 169 insertions(+)
create mode 100644 tools/testing/selftests/kvm/arm64/vgic_group_v2.c
diff --git a/tools/testing/selftests/kvm/Makefile.kvm b/tools/testing/selftests/kvm/Makefile.kvm
index df729a70124f..878d7cb92555 100644
--- a/tools/testing/selftests/kvm/Makefile.kvm
+++ b/tools/testing/selftests/kvm/Makefile.kvm
@@ -178,6 +178,7 @@ TEST_GEN_PROGS_arm64 += arm64/vgic_init
TEST_GEN_PROGS_arm64 += arm64/vgic_irq
TEST_GEN_PROGS_arm64 += arm64/vgic_lpi_stress
TEST_GEN_PROGS_arm64 += arm64/vgic_group_iidr
+TEST_GEN_PROGS_arm64 += arm64/vgic_group_v2
TEST_GEN_PROGS_arm64 += arm64/vpmu_counter_access
TEST_GEN_PROGS_arm64 += arm64/no-vgic-v3
TEST_GEN_PROGS_arm64 += arm64/idreg-idst
diff --git a/tools/testing/selftests/kvm/arm64/vgic_group_v2.c b/tools/testing/selftests/kvm/arm64/vgic_group_v2.c
new file mode 100644
index 000000000000..6d4bad44bae7
--- /dev/null
+++ b/tools/testing/selftests/kvm/arm64/vgic_group_v2.c
@@ -0,0 +1,168 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * vgic_group_v2.c - Test GICv2 IGROUPR behaviour across IIDR revisions
+ *
+ * Validate that the GICD_IIDR implementation revision controls GICv2
+ * IGROUPR writability for both guest and userspace:
+ * Default (no IIDR write): groups writable (implementation_rev defaults to 3)
+ * Rev 1: IGROUPR reads as zero (group 0), writes ignored
+ * Rev 2: IGROUPR is guest and userspace configurable
+ */
+#include <linux/sizes.h>
+
+#include "test_util.h"
+#include "kvm_util.h"
+#include "processor.h"
+#include "gic.h"
+#include "gic_v3.h"
+#include "vgic.h"
+
+#define NR_IRQS 64
+
+#define V2_DIST_BASE 0x8000000ULL
+#define V2_CPU_BASE 0x8010000ULL
+#define V2_DIST_GVA ((volatile void *)V2_DIST_BASE)
+
+#define SPI_IGROUPR (GICD_IGROUPR + (32 / 32) * 4)
+
+static uint64_t shared_rev;
+static uint64_t guest_result;
+
+static void guest_code(void)
+{
+ uint32_t before, after;
+
+ before = readl(V2_DIST_GVA + SPI_IGROUPR);
+ writel(0x5a5a5a5a, V2_DIST_GVA + SPI_IGROUPR);
+ after = readl(V2_DIST_GVA + SPI_IGROUPR);
+
+ guest_result = ((uint64_t)before << 32) | after;
+ GUEST_DONE();
+}
+
+static int create_v2_gic(struct kvm_vm *vm)
+{
+ uint32_t nr_irqs = NR_IRQS;
+ uint64_t addr;
+ int gic_fd;
+
+ gic_fd = __kvm_create_device(vm, KVM_DEV_TYPE_ARM_VGIC_V2);
+ if (gic_fd < 0)
+ return gic_fd;
+
+ addr = V2_DIST_BASE;
+ kvm_device_attr_set(gic_fd, KVM_DEV_ARM_VGIC_GRP_ADDR,
+ KVM_VGIC_V2_ADDR_TYPE_DIST, &addr);
+ addr = V2_CPU_BASE;
+ kvm_device_attr_set(gic_fd, KVM_DEV_ARM_VGIC_GRP_ADDR,
+ KVM_VGIC_V2_ADDR_TYPE_CPU, &addr);
+
+ virt_map(vm, V2_DIST_BASE, V2_DIST_BASE,
+ vm_calc_num_guest_pages(vm->mode, SZ_64K));
+ virt_map(vm, V2_CPU_BASE, V2_CPU_BASE,
+ vm_calc_num_guest_pages(vm->mode, SZ_64K));
+
+ kvm_device_attr_set(gic_fd, KVM_DEV_ARM_VGIC_GRP_NR_IRQS,
+ 0, &nr_irqs);
+ return gic_fd;
+}
+
+static void run_test(int set_iidr_rev)
+{
+ struct kvm_vcpu *vcpus[1];
+ struct kvm_vm *vm;
+ struct ucall uc;
+ uint32_t before, after, igroupr, iidr;
+ int gic_fd;
+ bool expect_writable;
+
+ if (set_iidr_rev >= 0)
+ pr_info("Testing GICv2 IIDR revision %d\n", set_iidr_rev);
+ else
+ pr_info("Testing GICv2 IIDR default (no write)\n");
+
+ test_disable_default_vgic();
+ vm = vm_create_with_vcpus(1, guest_code, vcpus);
+
+ gic_fd = create_v2_gic(vm);
+ TEST_REQUIRE(gic_fd >= 0);
+
+ if (set_iidr_rev >= 0) {
+ kvm_device_attr_get(gic_fd, KVM_DEV_ARM_VGIC_GRP_DIST_REGS,
+ GICD_IIDR, &iidr);
+ iidr &= ~GICD_IIDR_REVISION_MASK;
+ iidr |= set_iidr_rev << GICD_IIDR_REVISION_SHIFT;
+ kvm_device_attr_set(gic_fd, KVM_DEV_ARM_VGIC_GRP_DIST_REGS,
+ GICD_IIDR, &iidr);
+ }
+
+ kvm_device_attr_set(gic_fd, KVM_DEV_ARM_VGIC_GRP_CTRL,
+ KVM_DEV_ARM_VGIC_CTRL_INIT, NULL);
+
+ /*
+ * Default (no IIDR write) gets implementation_rev=3 from vgic_init(),
+ * so groups should be writable. Rev 1 = not writable. Rev 2+ = writable.
+ */
+ expect_writable = (set_iidr_rev != 1);
+
+ /* Test userspace IGROUPR write */
+ igroupr = 0xa5a5a5a5;
+ kvm_device_attr_set(gic_fd, KVM_DEV_ARM_VGIC_GRP_DIST_REGS,
+ SPI_IGROUPR, &igroupr);
+ igroupr = 0;
+ kvm_device_attr_get(gic_fd, KVM_DEV_ARM_VGIC_GRP_DIST_REGS,
+ SPI_IGROUPR, &igroupr);
+
+ if (expect_writable)
+ TEST_ASSERT(igroupr == 0xa5a5a5a5,
+ "Userspace write should succeed: got 0x%08x", igroupr);
+ else
+ TEST_ASSERT(igroupr == 0x00000000,
+ "Userspace write should be ignored: got 0x%08x", igroupr);
+
+ /* Reset IGROUPR to 0 via userspace for rev 2+ before guest test */
+ if (expect_writable) {
+ igroupr = 0;
+ kvm_device_attr_set(gic_fd, KVM_DEV_ARM_VGIC_GRP_DIST_REGS,
+ SPI_IGROUPR, &igroupr);
+ }
+
+ /* Test guest IGROUPR write */
+ sync_global_to_guest(vm, guest_result);
+ vcpu_run(vcpus[0]);
+
+ switch (get_ucall(vcpus[0], &uc)) {
+ case UCALL_ABORT:
+ REPORT_GUEST_ASSERT(uc);
+ break;
+ case UCALL_DONE:
+ break;
+ default:
+ TEST_FAIL("Unexpected ucall %lu", uc.cmd);
+ }
+
+ sync_global_from_guest(vm, guest_result);
+ before = guest_result >> 32;
+ after = guest_result & 0xffffffff;
+
+ TEST_ASSERT(before == 0x00000000,
+ "Initial IGROUPR should be 0 (group 0): got 0x%08x", before);
+
+ if (expect_writable)
+ TEST_ASSERT(after == 0x5a5a5a5a,
+ "Guest write should succeed: got 0x%08x", after);
+ else
+ TEST_ASSERT(after == 0x00000000,
+ "Guest write should be ignored: got 0x%08x", after);
+
+ close(gic_fd);
+ kvm_vm_free(vm);
+}
+
+int main(int argc, char *argv[])
+{
+ run_test(-1); /* default */
+ run_test(1); /* rev 1 */
+ run_test(2); /* rev 2 */
+ return 0;
+}
--
2.51.0
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