linux-kernel - Re: [RFC PATCH v2 2/9] KVM: arm64: nv: selftests: Add simple test to run guest code in vEL2

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Message-ID: <aEZRnBK7pD4rkgdi@vm4>
Date: Mon, 9 Jun 2025 12:14:36 +0900
From: Itaru Kitayama <itaru.kitayama@...ux.dev>
To: Ganapatrao Kulkarni <gankulkarni@...amperecomputing.com>
Cc: linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.linux.dev,
	linux-kselftest@...r.kernel.org, linux-kernel@...r.kernel.org,
	maz@...nel.org, oliver.upton@...ux.dev, joey.gouly@....com,
	suzuki.poulose@....com, yuzenghui@...wei.com, seanjc@...gle.com,
	darren@...amperecomputing.com
Subject: Re: [RFC PATCH v2 2/9] KVM: arm64: nv: selftests: Add simple test to
 run guest code in vEL2

On Mon, May 12, 2025 at 03:52:44AM -0700, Ganapatrao Kulkarni wrote:
> Add simple test to run guest code with NV enabled. With NV enabled,
> guest code runs in vEL2 context.
> 
> Signed-off-by: Ganapatrao Kulkarni <gankulkarni@...amperecomputing.com>
> ---
>  .../selftests/kvm/arm64/nv_guest_hypervisor.c | 68 +++++++++++++++++++
>  1 file changed, 68 insertions(+)
>  create mode 100644 tools/testing/selftests/kvm/arm64/nv_guest_hypervisor.c
> 
> diff --git a/tools/testing/selftests/kvm/arm64/nv_guest_hypervisor.c b/tools/testing/selftests/kvm/arm64/nv_guest_hypervisor.c
> new file mode 100644
> index 000000000000..7d7b3944e229
> --- /dev/null
> +++ b/tools/testing/selftests/kvm/arm64/nv_guest_hypervisor.c
> @@ -0,0 +1,68 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (c) 2025 Ampere Computing LLC
> + */
> +#include <kvm_util.h>
> +#include <nv_util.h>
> +#include <processor.h>
> +
> +static void guest_code(void)
> +{
> +	if (read_sysreg(CurrentEL) == CurrentEL_EL2)
> +		GUEST_PRINTF("Test PASS\n");
> +	else
> +		GUEST_FAIL("Fail to run in vEL2\n");
> +
> +	GUEST_DONE();
> +}
> +
> +static void guest_undef_handler(struct ex_regs *regs)
> +{
> +	GUEST_FAIL("Unexpected exception far_el1 = 0x%lx", read_sysreg(far_el1));
> +}
> +
> +static void test_run_vcpu(struct kvm_vcpu *vcpu)
> +{
> +	struct ucall uc;
> +
> +	do {
> +		vcpu_run(vcpu);
> +
> +		switch (get_ucall(vcpu, &uc)) {
> +		case UCALL_ABORT:
> +			REPORT_GUEST_ASSERT(uc);
> +			break;
> +		case UCALL_PRINTF:
> +			printf("%s", uc.buffer);
> +			break;
> +		case UCALL_DONE:
> +			break;
> +		default:
> +			TEST_FAIL("Unknown ucall %lu", uc.cmd);
> +		}
> +	} while (uc.cmd != UCALL_DONE);
> +}
> +
> +static void test_nv_guest_hypervisor(void)
> +{
> +	struct kvm_vcpu *vcpu;
> +	struct kvm_vm *vm;
> +	int gic_fd = -1;
> +
> +	vm = nv_vm_create_with_vcpus_gic(1, &vcpu, &gic_fd, guest_code);
> +	vm_init_descriptor_tables(vm);
> +	vcpu_init_descriptor_tables(vcpu);
> +	vm_install_sync_handler(vm, VECTOR_SYNC_CURRENT,
> +				ESR_ELx_EC_UNKNOWN, guest_undef_handler);
> +
> +	test_run_vcpu(vcpu);
> +
> +	vgic_v3_close(gic_fd);
> +	kvm_vm_free(vm);
> +}
> +
> +int main(int argc, char *argv[])
> +{
> +	test_nv_guest_hypervisor();
> +	return 0;
> +}

The kernel this v2 series applied is based off of the latest kvmarm-next 
and tested this on QEMU TCG mode with the kvm-arm.mode=nested option added at boot.

Tested-by: Itaru Kitayama <itaru.kitayama@...itsu.com>

> -- 
> 2.48.1
>