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

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Date:   Thu, 6 Feb 2020 11:08:28 -0800
From:   Krish Sadhukhan <krish.sadhukhan@...cle.com>
To:     Wei Huang <wei.huang2@....com>, 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 2/6/20 9:39 AM, Wei Huang wrote:
> 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.

Is it better to give this file a generic name, say, nsvm_tests or 
something like that, and place all future nested SVM tests in it, rather 
than creating a separate file for each nested test ?
>
> 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;
>> +}
>