Commit 85acc29f authored by Marc Zyngier's avatar Marc Zyngier Committed by Oliver Upton
Browse files

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



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: default avatarMarc Zyngier <maz@kernel.org>
Reviewed-by: default avatarSebastian 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: default avatarOliver Upton <oliver.upton@linux.dev>
parent f1edb159

tools/testing/selftests/kvm/Makefile.kvm

+1 −0
Original line number Diff line number Diff line
@@ -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

tools/testing/selftests/kvm/arm64/kvm-uuid.c

0 → 100644
+70 −0
Original line number Diff line number Diff line 
// 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;

}