linux-kernel - Re: [V2 PATCH 5/8] KVM: selftests: x86: delete svm_vmcall

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Date:   Wed, 21 Sep 2022 14:34:41 -0700
From:   David Matlack <dmatlack@...gle.com>
To:     Vishal Annapurve <vannapurve@...gle.com>
Cc:     x86@...nel.org, kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-kselftest@...r.kernel.org, pbonzini@...hat.com,
        shuah@...nel.org, bgardon@...gle.com, seanjc@...gle.com,
        oupton@...gle.com, peterx@...hat.com, vkuznets@...hat.com
Subject: Re: [V2 PATCH 5/8] KVM: selftests: x86: delete svm_vmcall_test

On Thu, Sep 15, 2022 at 12:04:45AM +0000, Vishal Annapurve wrote:
> svm_vmcall_test is superseded by fix_hypercall_test.

Please provide a more detailed description of why svm_vmcall_test is
being dropped. e.g. What do you mean by "superseded" specifically?

I ask because this will be helpful context for future readers of this
commit. I also ask because it's not clear to me that fix_hypercall_test
is a 1:1 replacement of svm_vmcall_test. e.g. svm_vmcall_test sets up an
L2 while fix_hypercall_test just executes in L1.

> 
> Suggested-by: Sean Christopherson <seanjc@...gle.com>
> Signed-off-by: Vishal Annapurve <vannapurve@...gle.com>
> ---
>  tools/testing/selftests/kvm/.gitignore        |  1 -
>  .../selftests/kvm/x86_64/svm_vmcall_test.c    | 74 -------------------
>  2 files changed, 75 deletions(-)
>  delete mode 100644 tools/testing/selftests/kvm/x86_64/svm_vmcall_test.c
> 
> diff --git a/tools/testing/selftests/kvm/.gitignore b/tools/testing/selftests/kvm/.gitignore
> index d625a3f83780..22e9a5b5488c 100644
> --- a/tools/testing/selftests/kvm/.gitignore
> +++ b/tools/testing/selftests/kvm/.gitignore
> @@ -36,7 +36,6 @@
>  /x86_64/sev_migrate_tests
>  /x86_64/smm_test
>  /x86_64/state_test
> -/x86_64/svm_vmcall_test
>  /x86_64/svm_int_ctl_test
>  /x86_64/svm_nested_soft_inject_test
>  /x86_64/sync_regs_test
> diff --git a/tools/testing/selftests/kvm/x86_64/svm_vmcall_test.c b/tools/testing/selftests/kvm/x86_64/svm_vmcall_test.c
> deleted file mode 100644
> index c3ac45df7483..000000000000
> --- a/tools/testing/selftests/kvm/x86_64/svm_vmcall_test.c
> +++ /dev/null
> @@ -1,74 +0,0 @@
> -// 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"
> -
> -static void l2_guest_code(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_guest_code,
> -			  &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[])
> -{
> -	struct kvm_vcpu *vcpu;
> -	vm_vaddr_t svm_gva;
> -	struct kvm_vm *vm;
> -
> -	TEST_REQUIRE(kvm_cpu_has(X86_FEATURE_SVM));
> -
> -	vm = vm_create_with_one_vcpu(&vcpu, l1_guest_code);
> -
> -	vcpu_alloc_svm(vm, &svm_gva);
> -	vcpu_args_set(vcpu, 1, svm_gva);
> -
> -	for (;;) {
> -		volatile struct kvm_run *run = vcpu->run;
> -		struct ucall uc;
> -
> -		vcpu_run(vcpu);
> -		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(vcpu, &uc)) {
> -		case UCALL_ABORT:
> -			REPORT_GUEST_ASSERT(uc);
> -			/* NOT REACHED */
> -		case UCALL_SYNC:
> -			break;
> -		case UCALL_DONE:
> -			goto done;
> -		default:
> -			TEST_FAIL("Unknown ucall 0x%lx.", uc.cmd);
> -		}
> -	}
> -done:
> -	kvm_vm_free(vm);
> -	return 0;
> -}
> -- 
> 2.37.2.789.g6183377224-goog
>