linux-kernel - Re: [RFC PATCH v5 15/29] KVM: selftests: TDX: Add TDX MSR read/write tests

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Message-ID: <ZeZltsBoMbclr4yX@yzhao56-desk.sh.intel.com>
Date: Tue, 5 Mar 2024 08:22:14 +0800
From: Yan Zhao <yan.y.zhao@...el.com>
To: Sagi Shahar <sagis@...gle.com>
CC: <linux-kselftest@...r.kernel.org>, Ackerley Tng <ackerleytng@...gle.com>,
	Ryan Afranji <afranji@...gle.com>, Erdem Aktas <erdemaktas@...gle.com>,
	"Isaku Yamahata" <isaku.yamahata@...el.com>, Sean Christopherson
	<seanjc@...gle.com>, Paolo Bonzini <pbonzini@...hat.com>, Shuah Khan
	<shuah@...nel.org>, "Peter Gonda" <pgonda@...gle.com>, Haibo Xu
	<haibo1.xu@...el.com>, Chao Peng <chao.p.peng@...ux.intel.com>, Vishal
 Annapurve <vannapurve@...gle.com>, Roger Wang <runanwang@...gle.com>, Vipin
 Sharma <vipinsh@...gle.com>, <jmattson@...gle.com>, <dmatlack@...gle.com>,
	<linux-kernel@...r.kernel.org>, <kvm@...r.kernel.org>, <linux-mm@...ck.org>
Subject: Re: [RFC PATCH v5 15/29] KVM: selftests: TDX: Add TDX MSR read/write
 tests

> +void verify_guest_msr_writes(void)
> +{
> +	struct kvm_vcpu *vcpu;
> +	struct kvm_vm *vm;
> +
> +	uint64_t data;
> +	int ret;
> +
> +	vm = td_create();
> +	td_initialize(vm, VM_MEM_SRC_ANONYMOUS, 0);
> +
> +	/*
> +	 * Set explicit MSR filter map to control access to the MSR registers
> +	 * used in the test.
> +	 */
> +	printf("\t ... Setting test MSR filter\n");
> +	ret = kvm_check_cap(KVM_CAP_X86_USER_SPACE_MSR);
> +	TEST_ASSERT(ret, "KVM_CAP_X86_USER_SPACE_MSR is unavailable");
> +	vm_enable_cap(vm, KVM_CAP_X86_USER_SPACE_MSR, KVM_MSR_EXIT_REASON_FILTER);
> +
> +	ret = kvm_check_cap(KVM_CAP_X86_MSR_FILTER);
> +	TEST_ASSERT(ret, "KVM_CAP_X86_MSR_FILTER is unavailable");
> +
> +	ret = ioctl(vm->fd, KVM_X86_SET_MSR_FILTER, &tdx_msr_test_filter);
> +	TEST_ASSERT(ret == 0,
> +		    "KVM_X86_SET_MSR_FILTER failed, ret: %i errno: %i (%s)",
> +		    ret, errno, strerror(errno));
> +
> +	vcpu = td_vcpu_add(vm, 0, guest_msr_write);
> +	td_finalize(vm);
> +
> +	printf("Verifying guest msr writes:\n");
> +
> +	printf("\t ... Running guest\n");
> +	/* Only the write to MSR_IA32_MISC_ENABLE should trigger an exit */
> +	td_vcpu_run(vcpu);
> +	TDX_TEST_CHECK_GUEST_FAILURE(vcpu);
> +	data = tdx_test_read_64bit_report_from_guest(vcpu);
> +	TEST_ASSERT_EQ(data, TDG_VP_VMCALL_INVALID_OPERAND);
> +
> +	td_vcpu_run(vcpu);
> +	TDX_TEST_ASSERT_SUCCESS(vcpu);
> +
> +	printf("\t ... Verifying MSR values writen by guest\n");
> +
> +	TEST_ASSERT_EQ(vcpu_get_msr(vcpu, MSR_X2APIC_APIC_ICR), 4);
> +	TEST_ASSERT_EQ(vcpu_get_msr(vcpu, MSR_IA32_MISC_ENABLE), 0x1800);
It's not staightforward to assert MSR_IA32_MISC_ENABLE is 0x1800.
Rather than assume MSR_IA32_MISC_ENABLE is reset to
(MSR_IA32_MISC_ENABLE_PEBS_UNAVAIL | MSR_IA32_MISC_ENABLE_BTS_UNAVAIL)
which is 0x1800, why not call vcpu_get_msr() before guest write and compare
the saved value here?

> +	TEST_ASSERT_EQ(vcpu_get_msr(vcpu, MSR_IA32_POWER_CTL), 6);
> +
> +	kvm_vm_free(vm);
> +	printf("\t ... PASSED\n");
> +}
> +
> +
>  int main(int argc, char **argv)
>  {
>  	setbuf(stdout, NULL);
> @@ -531,6 +738,8 @@ int main(int argc, char **argv)
>  	run_in_new_process(&verify_get_td_vmcall_info);
>  	run_in_new_process(&verify_guest_writes);
>  	run_in_new_process(&verify_guest_reads);
> +	run_in_new_process(&verify_guest_msr_writes);
> +	run_in_new_process(&verify_guest_msr_reads);
>  
>  	return 0;
>  }
> -- 
> 2.43.0.472.g3155946c3a-goog
> 
>