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KVM: arm64: selftest: Add standalone test checking for KVM's own UUID

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Tinkering with UUIDs is a perilious task, and the KVM UUID gets
broken at times. In order to spot this early enough, add a selftest
that will shout if the expected value isn't found.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Sebastian Ott <sebott@redhat.com>
Link: https://lore.kernel.org/r/20250721130558.50823-1-jackabt.amazon@gmail.com
Link: https://lore.kernel.org/r/20250806171341.1521210-1-maz@kernel.org
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
This commit is contained in:
Marc Zyngier 2025-08-06 18:13:41 +01:00 committed by Oliver Upton
parent f1edb15920
commit 85acc29f90
2 changed files with 71 additions and 0 deletions
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1
tools/testing/selftests/kvm/Makefile.kvm
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@ -167,6 +167,7 @@ TEST_GEN_PROGS_arm64 += arm64/vgic_irq
TEST_GEN_PROGS_arm64 += arm64/vgic_lpi_stress
TEST_GEN_PROGS_arm64 += arm64/vpmu_counter_access
TEST_GEN_PROGS_arm64 += arm64/no-vgic-v3
TEST_GEN_PROGS_arm64 += arm64/kvm-uuid
TEST_GEN_PROGS_arm64 += access_tracking_perf_test
TEST_GEN_PROGS_arm64 += arch_timer
TEST_GEN_PROGS_arm64 += coalesced_io_test

70
tools/testing/selftests/kvm/arm64/kvm-uuid.c Normal file
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@ -0,0 +1,70 @@
// SPDX-License-Identifier: GPL-2.0
// Check that nobody has tampered with KVM's UID
#include <errno.h>
#include <linux/arm-smccc.h>
#include <asm/kvm.h>
#include <kvm_util.h>
#include "processor.h"
/*
* Do NOT redefine these constants, or try to replace them with some
* "common" version. They are hardcoded here to detect any potential
* breakage happening in the rest of the kernel.
*
* KVM UID value: 28b46fb6-2ec5-11e9-a9ca-4b564d003a74
*/
#define ARM_SMCCC_VENDOR_HYP_UID_KVM_REG_0 0xb66fb428U
#define ARM_SMCCC_VENDOR_HYP_UID_KVM_REG_1 0xe911c52eU
#define ARM_SMCCC_VENDOR_HYP_UID_KVM_REG_2 0x564bcaa9U
#define ARM_SMCCC_VENDOR_HYP_UID_KVM_REG_3 0x743a004dU
static void guest_code(void)
{
struct arm_smccc_res res = {};
smccc_hvc(ARM_SMCCC_VENDOR_HYP_CALL_UID_FUNC_ID, 0, 0, 0, 0, 0, 0, 0, &res);
__GUEST_ASSERT(res.a0 == ARM_SMCCC_VENDOR_HYP_UID_KVM_REG_0 &&
res.a1 == ARM_SMCCC_VENDOR_HYP_UID_KVM_REG_1 &&
res.a2 == ARM_SMCCC_VENDOR_HYP_UID_KVM_REG_2 &&
res.a3 == ARM_SMCCC_VENDOR_HYP_UID_KVM_REG_3,
"Unexpected KVM-specific UID %lx %lx %lx %lx\n", res.a0, res.a1, res.a2, res.a3);
GUEST_DONE();
}
int main (int argc, char *argv[])
{
struct kvm_vcpu *vcpu;
struct kvm_vm *vm;
struct ucall uc;
bool guest_done = false;
vm = vm_create_with_one_vcpu(&vcpu, guest_code);
while (!guest_done) {
vcpu_run(vcpu);
switch (get_ucall(vcpu, &uc)) {
case UCALL_SYNC:
break;
case UCALL_DONE:
guest_done = true;
break;
case UCALL_ABORT:
REPORT_GUEST_ASSERT(uc);
break;
case UCALL_PRINTF:
printf("%s", uc.buffer);
break;
default:
TEST_FAIL("Unexpected guest exit");
}
}
kvm_vm_free(vm);
return 0;
}