[PATCH 3/3] KVM: arm64: selftests: Add vgic IIDR revision test

David Woodhouse
2026-04-07T21:11:23Z

From: David Woodhouse <dwmw@amazon.co.uk>

Test that the GICD_IIDR implementation revision correctly controls
guest-visible behaviour for GICv3:

Revision 1: IGROUPR reads as all-ones (group 1), writes are ignored.
GICR_CTLR.{IR,CES} not advertised.
Revision 2: IGROUPR is guest-configurable (read/write).
GICR_CTLR.{IR,CES} not advertised.
Revision 3: IGROUPR is guest-configurable (read/write).
GICR_CTLR.{IR,CES} advertised.

For each revision, the test sets the IIDR via KVM_DEV_ARM_VGIC_GRP_DIST_REGS
before initializing the vGIC, then runs a guest that verifies the
expected IGROUPR and GICR_CTLR behaviour.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
---
tools/testing/selftests/kvm/Makefile.kvm | 1 +
.../selftests/kvm/arm64/vgic_group_iidr.c | 112 ++++++++++++++++++
2 files changed, 113 insertions(+)
create mode 100644 tools/testing/selftests/kvm/arm64/vgic_group_iidr.c

diff --git a/tools/testing/selftests/kvm/Makefile.kvm b/tools/testing/selftests/kvm/Makefile.kvm
index 6471fa214a9f..df729a70124f 100644
--- a/tools/testing/selftests/kvm/Makefile.kvm
+++ b/tools/testing/selftests/kvm/Makefile.kvm
@@ -177,6 +177,7 @@ TEST_GEN_PROGS_arm64 += arm64/vcpu_width_config
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/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_iidr.c b/tools/testing/selftests/kvm/arm64/vgic_group_iidr.c
new file mode 100644
index 000000000000..d5c20a41162c
--- /dev/null
+++ b/tools/testing/selftests/kvm/arm64/vgic_group_iidr.c
@@ -0,0 +1,112 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * vgic_group_iidr.c - Test IGROUPR behaviour across IIDR revisions
+ *
+ * Validate that the GICD_IIDR implementation revision controls
+ * IGROUPR semantics for GICv3:
+ * Rev 1: IGROUPR reads as all-ones (group 1), writes ignored
+ * Rev 2+: IGROUPR is guest-configurable (read/write)
+ */
+#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 128
+#define SPI_IGROUPR (GICD_IGROUPR + (32 / 32) * 4) /* intids 32-63 */
+
+static volatile uint64_t shared_rev;
+
+static void guest_code(void)
+{
+ uint32_t val;
+
+ val = readl(GICD_BASE_GVA + SPI_IGROUPR);
+
+ if (shared_rev == 1) {
+ /* Rev 1: all group 1 (RAO), writes ignored */
+ GUEST_ASSERT_EQ(val, 0xffffffff);
+ writel(0x0, GICD_BASE_GVA + SPI_IGROUPR);
+ val = readl(GICD_BASE_GVA + SPI_IGROUPR);
+ GUEST_ASSERT_EQ(val, 0xffffffff);
+ } else {
+ /* Rev 2/3: writable, default 0 */
+ writel(0xa5a5a5a5, GICD_BASE_GVA + SPI_IGROUPR);
+ val = readl(GICD_BASE_GVA + SPI_IGROUPR);
+ GUEST_ASSERT_EQ(val, 0xa5a5a5a5);
+ }
+
+ /* Rev 3: GICR_CTLR advertises IR and CES. Rev 1/2: it does not. */
+ val = readl(GICR_BASE_GVA + GICR_CTLR);
+ if (shared_rev >= 3)
+ GUEST_ASSERT(val & (GICR_CTLR_IR | GICR_CTLR_CES));
+ else
+ GUEST_ASSERT(!(val & (GICR_CTLR_IR | GICR_CTLR_CES)));
+
+ GUEST_DONE();
+}
+
+static void run_test(int rev)
+{
+ struct kvm_vcpu *vcpus[1];
+ struct kvm_vm *vm;
+ struct ucall uc;
+ uint32_t iidr;
+ int gic_fd;
+
+ pr_info("Testing IIDR revision %d\n", rev);
+
+ test_disable_default_vgic();
+ vm = vm_create_with_vcpus(1, guest_code, vcpus);
+
+ gic_fd = __vgic_v3_setup(vm, 1, NR_IRQS);
+ TEST_ASSERT(gic_fd >= 0, "Failed to create vGICv3");
+
+ /* Set the requested IIDR revision before init. */
+ kvm_device_attr_get(gic_fd, KVM_DEV_ARM_VGIC_GRP_DIST_REGS,
+ GICD_IIDR, &iidr);
+ iidr &= ~GICD_IIDR_REVISION_MASK;
+ iidr |= rev << GICD_IIDR_REVISION_SHIFT;
+ kvm_device_attr_set(gic_fd, KVM_DEV_ARM_VGIC_GRP_DIST_REGS,
+ GICD_IIDR, &iidr);
+
+ __vgic_v3_init(gic_fd);
+
+ /* Verify the revision was applied. */
+ kvm_device_attr_get(gic_fd, KVM_DEV_ARM_VGIC_GRP_DIST_REGS,
+ GICD_IIDR, &iidr);
+ TEST_ASSERT(((iidr & GICD_IIDR_REVISION_MASK) >> GICD_IIDR_REVISION_SHIFT) == rev,
+ "IIDR revision readback: expected %d, got %d",
+ rev, (iidr & GICD_IIDR_REVISION_MASK) >> GICD_IIDR_REVISION_SHIFT);
+
+ /* Tell the guest which revision we set. */
+ sync_global_to_guest(vm, shared_rev);
+ shared_rev = rev;
+ sync_global_to_guest(vm, shared_rev);
+
+ 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);
+ }
+
+ close(gic_fd);
+ kvm_vm_free(vm);
+}
+
+int main(int argc, char *argv[])
+{
+ run_test(1);
+ run_test(2);
+ run_test(3);
+ return 0;
+}
--
2.51.0