linux-kernel - Re: [RFC PATCH v5 23/29] KVM: selftests: TDX: Add shared memory test

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Date: Wed, 6 Mar 2024 09:20:35 +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 23/29] KVM: selftests: TDX: Add shared memory test

> +int verify_shared_mem(void)
> +{
> +	struct kvm_vm *vm;
> +	struct kvm_vcpu *vcpu;
> +
> +	vm_vaddr_t test_mem_private_gva;
> +	uint32_t *test_mem_hva;
> +
> +	vm = td_create();
> +	td_initialize(vm, VM_MEM_SRC_ANONYMOUS, 0);
> +	vcpu = td_vcpu_add(vm, 0, guest_shared_mem);
> +
> +	/*
> +	 * Set up shared memory page for testing by first allocating as private
> +	 * and then mapping the same GPA again as shared. This way, the TD does
> +	 * not have to remap its page tables at runtime.
> +	 */
> +	test_mem_private_gva = vm_vaddr_alloc(vm, vm->page_size,
> +					      TDX_SHARED_MEM_TEST_PRIVATE_GVA);
> +	TEST_ASSERT_EQ(test_mem_private_gva, TDX_SHARED_MEM_TEST_PRIVATE_GVA);
> +
> +	test_mem_hva = addr_gva2hva(vm, test_mem_private_gva);
> +	TEST_ASSERT(test_mem_hva != NULL,
> +		    "Guest address not found in guest memory regions\n");
> +
> +	test_mem_private_gpa = addr_gva2gpa(vm, test_mem_private_gva);
> +	virt_pg_map_shared(vm, TDX_SHARED_MEM_TEST_SHARED_GVA,
> +			   test_mem_private_gpa);
> +
> +	test_mem_shared_gpa = test_mem_private_gpa | BIT_ULL(vm->pa_bits - 1);
Why not use vm->arch.s_bit?

> +	sync_global_to_guest(vm, test_mem_private_gpa);
test_mem_private_gpa is not used in guest. No need to sync.

> +	sync_global_to_guest(vm, test_mem_shared_gpa);
> +
> +	td_finalize(vm);
> +
> +	printf("Verifying shared memory accesses for TDX\n");
> +
> +	/* Begin guest execution; guest writes to shared memory. */
> +	printf("\t ... Starting guest execution\n");
> +
> +	/* Handle map gpa as shared */
> +	td_vcpu_run(vcpu);
> +	TDX_TEST_CHECK_GUEST_FAILURE(vcpu);
> +
> +	td_vcpu_run(vcpu);
> +	TDX_TEST_ASSERT_IO(vcpu, TDX_SHARED_MEM_TEST_INFO_PORT, 4,
> +			   TDG_VP_VMCALL_INSTRUCTION_IO_WRITE);
> +	TEST_ASSERT_EQ(*test_mem_hva, TDX_SHARED_MEM_TEST_GUEST_WRITE_VALUE);
> +
> +	*test_mem_hva = TDX_SHARED_MEM_TEST_HOST_WRITE_VALUE;
> +	td_vcpu_run(vcpu);
> +	TDX_TEST_ASSERT_IO(vcpu, TDX_SHARED_MEM_TEST_INFO_PORT, 4,
> +			   TDG_VP_VMCALL_INSTRUCTION_IO_WRITE);
> +	TEST_ASSERT_EQ(
> +		*(uint32_t *)((void *)vcpu->run + vcpu->run->io.data_offset),
> +		TDX_SHARED_MEM_TEST_HOST_WRITE_VALUE);
> +
> +	printf("\t ... PASSED\n");
> +
> +	kvm_vm_free(vm);
> +
> +	return 0;
> +}