[PATCH 12/12] KVM: arm64: Add selftest checking how the absence of GICv3 is handled

Marc Zyngier
2024-08-20T10:06:21Z

Given how tortuous and fragile the whole lack-of-GICv3 story is,
add a selftest checking that we don't regress it.

Signed-off-by: Marc Zyngier <maz@kernel.org>
---
tools/testing/selftests/kvm/Makefile | 1 +
.../selftests/kvm/aarch64/no-vgic-v3.c | 170 ++++++++++++++++++
2 files changed, 171 insertions(+)
create mode 100644 tools/testing/selftests/kvm/aarch64/no-vgic-v3.c

diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
index 48d32c5aa3eb..f66b37acc0b0 100644
--- a/tools/testing/selftests/kvm/Makefile
+++ b/tools/testing/selftests/kvm/Makefile
@@ -163,6 +163,7 @@ TEST_GEN_PROGS_aarch64 += aarch64/vgic_init
TEST_GEN_PROGS_aarch64 += aarch64/vgic_irq
TEST_GEN_PROGS_aarch64 += aarch64/vgic_lpi_stress
TEST_GEN_PROGS_aarch64 += aarch64/vpmu_counter_access
+TEST_GEN_PROGS_aarch64 += aarch64/no-vgic-v3
TEST_GEN_PROGS_aarch64 += access_tracking_perf_test
TEST_GEN_PROGS_aarch64 += arch_timer
TEST_GEN_PROGS_aarch64 += demand_paging_test
diff --git a/tools/testing/selftests/kvm/aarch64/no-vgic-v3.c b/tools/testing/selftests/kvm/aarch64/no-vgic-v3.c
new file mode 100644
index 000000000000..27169afc94c6
--- /dev/null
+++ b/tools/testing/selftests/kvm/aarch64/no-vgic-v3.c
@@ -0,0 +1,170 @@
+// SPDX-License-Identifier: GPL-2.0
+
+// Check that, on a GICv3 system, not configuring GICv3 correctly
+// results in all of the sysregs generating an UNDEF exception.
+
+#include <test_util.h>
+#include <kvm_util.h>
+#include <processor.h>
+
+static volatile bool handled;
+
+#define __check_sr_read(r) \
+ do { \
+ uint64_t val; \
+ \
+ handled = false; \
+ dsb(sy); \
+ val = read_sysreg_s(SYS_ ## r); \
+ (void)val; \
+ } while(0)
+
+#define __check_sr_write(r) \
+ do { \
+ handled = false; \
+ dsb(sy); \
+ write_sysreg_s(0, SYS_ ## r); \
+ isb(); \
+ } while(0)
+
+/* Fatal checks */
+#define check_sr_read(r) \
+ do { \
+ __check_sr_read(r); \
+ __GUEST_ASSERT(handled, #r " no read trap"); \
+ } while(0)
+
+#define check_sr_write(r) \
+ do { \
+ __check_sr_write(r); \
+ __GUEST_ASSERT(handled, #r " no write trap"); \
+ } while(0)
+
+#define check_sr_rw(r) \
+ do { \
+ check_sr_read(r); \
+ check_sr_write(r); \
+ } while(0)
+
+/* Non-fatal checks */
+#define check_sr_read_maybe(r) \
+ do { \
+ __check_sr_read(r); \
+ if (!handled) \
+ GUEST_PRINTF(#r " read not trapping (OK)\n"); \
+ } while(0)
+
+#define check_sr_write_maybe(r) \
+ do { \
+ __check_sr_write(r); \
+ if (!handled) \
+ GUEST_PRINTF(#r " write not trapping (OK)\n"); \
+ } while(0)
+
+static void guest_code(void)
+{
+ /*
+ * Check that we advertise that ID_AA64PFR0_EL1.GIC == 0, having
+ * hidden the feature at runtime without any other userspace action.
+ */
+ __GUEST_ASSERT(FIELD_GET(ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_GIC),
+ read_sysreg(id_aa64pfr0_el1)) == 0,
+ "GICv3 wrongly advertised");
+
+ /*
+ * Access all GICv3 registers, and fail if we don't get an UNDEF.
+ * Note that we happily access all the APxRn registers without
+ * checking their existance, as all we want to see is a failure.
+ */
+ check_sr_rw(ICC_PMR_EL1);
+ check_sr_read(ICC_IAR0_EL1);
+ check_sr_write(ICC_EOIR0_EL1);
+ check_sr_rw(ICC_HPPIR0_EL1);
+ check_sr_rw(ICC_BPR0_EL1);
+ check_sr_rw(ICC_AP0R0_EL1);
+ check_sr_rw(ICC_AP0R1_EL1);
+ check_sr_rw(ICC_AP0R2_EL1);
+ check_sr_rw(ICC_AP0R3_EL1);
+ check_sr_rw(ICC_AP1R0_EL1);
+ check_sr_rw(ICC_AP1R1_EL1);
+ check_sr_rw(ICC_AP1R2_EL1);
+ check_sr_rw(ICC_AP1R3_EL1);
+ check_sr_write(ICC_DIR_EL1);
+ check_sr_read(ICC_RPR_EL1);
+ check_sr_write(ICC_SGI1R_EL1);
+ check_sr_write(ICC_ASGI1R_EL1);
+ check_sr_write(ICC_SGI0R_EL1);
+ check_sr_read(ICC_IAR1_EL1);
+ check_sr_write(ICC_EOIR1_EL1);
+ check_sr_rw(ICC_HPPIR1_EL1);
+ check_sr_rw(ICC_BPR1_EL1);
+ check_sr_rw(ICC_CTLR_EL1);
+ check_sr_rw(ICC_IGRPEN0_EL1);
+ check_sr_rw(ICC_IGRPEN1_EL1);
+
+ /*
+ * ICC_SRE_EL1 may not be trappable, as ICC_SRE_EL2.Enable can
+ * be RAO/WI
+ */
+ check_sr_read_maybe(ICC_SRE_EL1);
+ check_sr_write_maybe(ICC_SRE_EL1);
+
+ GUEST_DONE();
+}
+
+static void guest_undef_handler(struct ex_regs *regs)
+{
+ /* Success, we've gracefully exploded! */
+ handled = true;
+ regs->pc += 4;
+}
+
+static void test_guest_no_gicv3(void)
+{
+ struct kvm_vcpu *vcpu;
+ struct kvm_vm *vm;
+ struct ucall uc;
+
+ /* Create a VM without a GICv3 */
+ vm = vm_create_with_one_vcpu(&vcpu, guest_code);
+
+ vm_init_descriptor_tables(vm);
+ vcpu_init_descriptor_tables(vcpu);
+
+ vm_install_sync_handler(vm, VECTOR_SYNC_CURRENT,
+ ESR_EC_UNKNOWN, guest_undef_handler);
+again:
+ vcpu_run(vcpu);
+
+ switch (get_ucall(vcpu, &uc)) {
+ case UCALL_ABORT:
+ REPORT_GUEST_ASSERT(uc);
+ break;
+ case UCALL_PRINTF:
+ printf("%s", uc.buffer);
+ goto again;
+ case UCALL_DONE:
+ break;
+ default:
+ TEST_FAIL("Unknown ucall %lu", uc.cmd);
+ }
+
+ kvm_vm_free(vm);
+}
+
+int main(int argc, char *argv[])
+{
+ struct kvm_vcpu *vcpu;
+ struct kvm_vm *vm;
+ uint64_t pfr0;
+
+ vm = vm_create_with_one_vcpu(&vcpu, NULL);
+ vcpu_get_reg(vcpu, KVM_ARM64_SYS_REG(SYS_ID_AA64PFR0_EL1), &pfr0);
+ __TEST_REQUIRE(FIELD_GET(ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_GIC), pfr0),
+ "GICv3 not supported.");
+ kvm_vm_free(vm);
+
+ test_guest_no_gicv3();
+
+ return 0;
+}
--
2.39.2