linux-kernel - Re: [PATCH v4 3/3] selftests: KVM: SVM: Add vmcall test

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Date:   Thu, 6 Feb 2020 11:39:31 -0600
From:   Wei Huang <wei.huang2@....com>
To:     Eric Auger <eric.auger@...hat.com>
Cc:     eric.auger.pro@...il.com, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org, pbonzini@...hat.com, vkuznets@...hat.com,
        thuth@...hat.com, drjones@...hat.com
Subject: Re: [PATCH v4 3/3] selftests: KVM: SVM: Add vmcall test

On 02/06 11:47, Eric Auger wrote:
> L2 guest calls vmcall and L1 checks the exit status does
> correspond.
> 
> Signed-off-by: Eric Auger <eric.auger@...hat.com>
> Reviewed-by: Vitaly Kuznetsov <vkuznets@...hat.com>
> Reviewed-by: Miaohe Lin <linmiaohe@...wei.com>

I verified this patch with my AMD box, both with nested=1 and nested=0. I
also intentionally changed the assertion of exit_code to a different
value (0x082) and the test complained about it. So the test is good.

# selftests: kvm: svm_vmcall_test
# ==== Test Assertion Failure ====
#   x86_64/svm_vmcall_test.c:64: false
#   pid=2485656 tid=2485656 - Interrupted system call
#      1        0x0000000000401387: main at svm_vmcall_test.c:72
#      2        0x00007fd0978d71a2: ?? ??:0
#      3        0x00000000004013ed: _start at ??:?
#   Failed guest assert: vmcb->control.exit_code == SVM_EXIT_VMMCALL
# Testing guest mode: PA-bits:ANY, VA-bits:48,  4K pages
# Guest physical address width detected: 48
not ok 15 selftests: kvm: svm_vmcall_test # exit=254

> 
> ---
> 
> v3 -> v4:
> - remove useless includes
> - collected Lin's R-b
> 
> v2 -> v3:
> - remove useless comment and add Vitaly's R-b
> ---
>  tools/testing/selftests/kvm/Makefile          |  1 +
>  .../selftests/kvm/x86_64/svm_vmcall_test.c    | 79 +++++++++++++++++++
>  2 files changed, 80 insertions(+)
>  create mode 100644 tools/testing/selftests/kvm/x86_64/svm_vmcall_test.c
> 
> diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
> index 2e770f554cae..b529d3b42c02 100644
> --- a/tools/testing/selftests/kvm/Makefile
> +++ b/tools/testing/selftests/kvm/Makefile
> @@ -26,6 +26,7 @@ TEST_GEN_PROGS_x86_64 += x86_64/vmx_dirty_log_test
>  TEST_GEN_PROGS_x86_64 += x86_64/vmx_set_nested_state_test
>  TEST_GEN_PROGS_x86_64 += x86_64/vmx_tsc_adjust_test
>  TEST_GEN_PROGS_x86_64 += x86_64/xss_msr_test
> +TEST_GEN_PROGS_x86_64 += x86_64/svm_vmcall_test
>  TEST_GEN_PROGS_x86_64 += clear_dirty_log_test
>  TEST_GEN_PROGS_x86_64 += dirty_log_test
>  TEST_GEN_PROGS_x86_64 += kvm_create_max_vcpus
> diff --git a/tools/testing/selftests/kvm/x86_64/svm_vmcall_test.c b/tools/testing/selftests/kvm/x86_64/svm_vmcall_test.c
> new file mode 100644
> index 000000000000..6d3565aab94e
> --- /dev/null
> +++ b/tools/testing/selftests/kvm/x86_64/svm_vmcall_test.c

Probably rename the file to svm_nested_vmcall_test.c. This matches with
the naming convention of VMX's nested tests. Otherwise people might not know
it is a nested one.

Everything else looks good.

> @@ -0,0 +1,79 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * svm_vmcall_test
> + *
> + * Copyright (C) 2020, Red Hat, Inc.
> + *
> + * Nested SVM testing: VMCALL
> + */
> +
> +#include "test_util.h"
> +#include "kvm_util.h"
> +#include "processor.h"
> +#include "svm_util.h"
> +
> +#define VCPU_ID		5
> +
> +static struct kvm_vm *vm;
> +
> +static inline void l2_vmcall(struct svm_test_data *svm)
> +{
> +	__asm__ __volatile__("vmcall");
> +}
> +
> +static void l1_guest_code(struct svm_test_data *svm)
> +{
> +	#define L2_GUEST_STACK_SIZE 64
> +	unsigned long l2_guest_stack[L2_GUEST_STACK_SIZE];
> +	struct vmcb *vmcb = svm->vmcb;
> +
> +	/* Prepare for L2 execution. */
> +	generic_svm_setup(svm, l2_vmcall,
> +			  &l2_guest_stack[L2_GUEST_STACK_SIZE]);
> +
> +	run_guest(vmcb, svm->vmcb_gpa);
> +
> +	GUEST_ASSERT(vmcb->control.exit_code == SVM_EXIT_VMMCALL);
> +	GUEST_DONE();
> +}
> +
> +int main(int argc, char *argv[])
> +{
> +	vm_vaddr_t svm_gva;
> +
> +	nested_svm_check_supported();
> +
> +	vm = vm_create_default(VCPU_ID, 0, (void *) l1_guest_code);
> +	vcpu_set_cpuid(vm, VCPU_ID, kvm_get_supported_cpuid());
> +
> +	vcpu_alloc_svm(vm, &svm_gva);
> +	vcpu_args_set(vm, VCPU_ID, 1, svm_gva);
> +
> +	for (;;) {
> +		volatile struct kvm_run *run = vcpu_state(vm, VCPU_ID);
> +		struct ucall uc;
> +
> +		vcpu_run(vm, VCPU_ID);
> +		TEST_ASSERT(run->exit_reason == KVM_EXIT_IO,
> +			    "Got exit_reason other than KVM_EXIT_IO: %u (%s)\n",
> +			    run->exit_reason,
> +			    exit_reason_str(run->exit_reason));
> +
> +		switch (get_ucall(vm, VCPU_ID, &uc)) {
> +		case UCALL_ABORT:
> +			TEST_ASSERT(false, "%s",
> +				    (const char *)uc.args[0]);
> +			/* NOT REACHED */
> +		case UCALL_SYNC:
> +			break;
> +		case UCALL_DONE:
> +			goto done;
> +		default:
> +			TEST_ASSERT(false,
> +				    "Unknown ucall 0x%x.", uc.cmd);
> +		}
> +	}
> +done:
> +	kvm_vm_free(vm);
> +	return 0;
> +}