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Message-Id: <20250417-kvm-selftest-sve-signal-v1-1-6330c2f3da0c@kernel.org>
Date: Thu, 17 Apr 2025 00:32:49 +0100
From: Mark Brown <broonie@...nel.org>
To: Paolo Bonzini <pbonzini@...hat.com>, Shuah Khan <shuah@...nel.org>,
Marc Zyngier <maz@...nel.org>, Oliver Upton <oliver.upton@...ux.dev>,
Joey Gouly <joey.gouly@....com>, Suzuki K Poulose <suzuki.poulose@....com>
Cc: Mark Rutland <mark.rutland@....com>, linux-kernel@...r.kernel.org,
kvm@...r.kernel.org, linux-kselftest@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.linux.dev,
Mark Brown <broonie@...nel.org>
Subject: [PATCH] KVM: selftests: add test for SVE host corruption
This test program, originally written by Mark Rutland and lightly modified
by me for upstream, verifies that we do not have the issues with host SVE
state being discarded which were fixed in
fbc7e61195e2 ("KVM: arm64: Unconditionally save+flush host FPSIMD/SVE/SME state")
by running a simple VM while checking the SVE register state for
corruption.
Signed-off-by: Mark Brown <broonie@...nel.org>
---
tools/testing/selftests/kvm/Makefile.kvm | 1 +
tools/testing/selftests/kvm/arm64/host_sve.c | 127 +++++++++++++++++++++++++++
2 files changed, 128 insertions(+)
diff --git a/tools/testing/selftests/kvm/Makefile.kvm b/tools/testing/selftests/kvm/Makefile.kvm
index f62b0a5aba35..d37072054a3d 100644
--- a/tools/testing/selftests/kvm/Makefile.kvm
+++ b/tools/testing/selftests/kvm/Makefile.kvm
@@ -147,6 +147,7 @@ TEST_GEN_PROGS_arm64 = $(TEST_GEN_PROGS_COMMON)
TEST_GEN_PROGS_arm64 += arm64/aarch32_id_regs
TEST_GEN_PROGS_arm64 += arm64/arch_timer_edge_cases
TEST_GEN_PROGS_arm64 += arm64/debug-exceptions
+TEST_GEN_PROGS_arm64 += arm64/host_sve
TEST_GEN_PROGS_arm64 += arm64/hypercalls
TEST_GEN_PROGS_arm64 += arm64/mmio_abort
TEST_GEN_PROGS_arm64 += arm64/page_fault_test
diff --git a/tools/testing/selftests/kvm/arm64/host_sve.c b/tools/testing/selftests/kvm/arm64/host_sve.c
new file mode 100644
index 000000000000..3826772fd470
--- /dev/null
+++ b/tools/testing/selftests/kvm/arm64/host_sve.c
@@ -0,0 +1,127 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+/*
+ * Host SVE: Check FPSIMD/SVE/SME save/restore over KVM_RUN ioctls.
+ *
+ * Copyright 2025 Arm, Ltd
+ */
+
+#include <errno.h>
+#include <signal.h>
+#include <sys/auxv.h>
+#include <asm/kvm.h>
+#include <kvm_util.h>
+
+#include "ucall_common.h"
+
+static void guest_code(void)
+{
+ for (int i = 0; i < 10; i++) {
+ GUEST_UCALL_NONE();
+ }
+
+ GUEST_DONE();
+}
+
+void handle_sigill(int sig, siginfo_t *info, void *ctx)
+{
+ ucontext_t *uctx = ctx;
+
+ printf(" < host signal %d >\n", sig);
+
+ /*
+ * Skip the UDF
+ */
+ uctx->uc_mcontext.pc += 4;
+}
+
+void register_sigill_handler(void)
+{
+ struct sigaction sa = {
+ .sa_sigaction = handle_sigill,
+ .sa_flags = SA_SIGINFO,
+ };
+ sigaction(SIGILL, &sa, NULL);
+}
+
+static void do_sve_roundtrip(void)
+{
+ unsigned long before, after;
+
+ /*
+ * Set all bits in a predicate register, force a save/restore via a
+ * SIGILL (which handle_sigill() will recover from), then report
+ * whether the value has changed.
+ */
+ asm volatile(
+ " .arch_extension sve\n"
+ " ptrue p0.B\n"
+ " cntp %[before], p0, p0.B\n"
+ " udf #0\n"
+ " cntp %[after], p0, p0.B\n"
+ : [before] "=r" (before),
+ [after] "=r" (after)
+ :
+ : "p0"
+ );
+
+ if (before != after) {
+ TEST_FAIL("Signal roundtrip discarded predicate bits (%ld => %ld)\n",
+ before, after);
+ } else {
+ printf("Signal roundtrip preserved predicate bits (%ld => %ld)\n",
+ before, after);
+ }
+}
+
+static void test_run(void)
+{
+ struct kvm_vcpu *vcpu;
+ struct kvm_vm *vm;
+ struct ucall uc;
+ bool guest_done = false;
+
+ register_sigill_handler();
+
+ vm = vm_create_with_one_vcpu(&vcpu, guest_code);
+
+ do_sve_roundtrip();
+
+ while (!guest_done) {
+
+ printf("Running VCPU...\n");
+ vcpu_run(vcpu);
+
+ switch (get_ucall(vcpu, &uc)) {
+ case UCALL_NONE:
+ do_sve_roundtrip();
+ do_sve_roundtrip();
+ break;
+ case UCALL_DONE:
+ guest_done = true;
+ break;
+ case UCALL_ABORT:
+ REPORT_GUEST_ASSERT(uc);
+ break;
+ default:
+ TEST_FAIL("Unexpected guest exit");
+ }
+ }
+
+ kvm_vm_free(vm);
+}
+
+int main(void)
+{
+ /*
+ * This is testing the host environment, we don't care about
+ * guest SVE support.
+ */
+ if (!(getauxval(AT_HWCAP) & HWCAP_SVE)) {
+ printf("SVE not supported\n");
+ return KSFT_SKIP;
+ }
+
+ test_run();
+ return 0;
+}
---
base-commit: 8ffd015db85fea3e15a77027fda6c02ced4d2444
change-id: 20250226-kvm-selftest-sve-signal-1add0d9d716c
Best regards,
--
Mark Brown <broonie@...nel.org>
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