linux-kernel - Re: [PATCH 6/6] KVM: selftests: x86: Add test for KVM_PRE_FAULT

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Message-ID: <b7d6bb0c-6ee4-4f93-a1a0-5ee6f49c0c59@intel.com>
Date: Tue, 23 Apr 2024 23:18:01 +0800
From: Xiaoyao Li <xiaoyao.li@...el.com>
To: Paolo Bonzini <pbonzini@...hat.com>, linux-kernel@...r.kernel.org,
 kvm@...r.kernel.org
Cc: isaku.yamahata@...el.com, binbin.wu@...ux.intel.com, seanjc@...gle.com,
 rick.p.edgecombe@...el.com
Subject: Re: [PATCH 6/6] KVM: selftests: x86: Add test for
 KVM_PRE_FAULT_MEMORY

On 4/19/2024 4:59 PM, Paolo Bonzini wrote:

..

> +static void __test_pre_fault_memory(unsigned long vm_type, bool private)
> +{
> +	const struct vm_shape shape = {
> +		.mode = VM_MODE_DEFAULT,
> +		.type = vm_type,
> +	};
> +	struct kvm_vcpu *vcpu;
> +	struct kvm_run *run;
> +	struct kvm_vm *vm;
> +	struct ucall uc;
> +
> +	uint64_t guest_test_phys_mem;
> +	uint64_t guest_test_virt_mem;
> +	uint64_t alignment, guest_page_size;
> +
> +	vm = vm_create_shape_with_one_vcpu(shape, &vcpu, guest_code);
> +
> +	alignment = guest_page_size = vm_guest_mode_params[VM_MODE_DEFAULT].page_size;
> +	guest_test_phys_mem = (vm->max_gfn - TEST_NPAGES) * guest_page_size;
> +#ifdef __s390x__
> +	alignment = max(0x100000UL, guest_page_size);
> +#else
> +	alignment = SZ_2M;
> +#endif
> +	guest_test_phys_mem = align_down(guest_test_phys_mem, alignment);
> +	guest_test_virt_mem = guest_test_phys_mem;

guest_test_virt_mem cannot be assigned as guest_test_phys_mem, which 
leads to following virt_map() fails with

==== Test Assertion Failure ====
   lib/x86_64/processor.c:197: sparsebit_is_set(vm->vpages_valid, (vaddr 
 >> vm->page_shift))
   pid=4773 tid=4773 errno=0 - Success
      1	0x000000000040f55c: __virt_pg_map at processor.c:197
      2	0x000000000040605e: virt_pg_map at kvm_util_base.h:1065
      3	 (inlined by) virt_map at kvm_util.c:1571
      4	0x0000000000402b75: __test_pre_fault_memory at 
pre_fault_memory_test.c:96
      5	0x000000000040246e: test_pre_fault_memory at 
pre_fault_memory_test.c:133 (discriminator 3)
      6	 (inlined by) main at pre_fault_memory_test.c:140 (discriminator 3)
      7	0x00007fcb68429d8f: ?? ??:0
      8	0x00007fcb68429e3f: ?? ??:0
      9	0x00000000004024e4: _start at ??:?
   Invalid virtual address, vaddr: 0xfffffffc00000

> +
> +	vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS,
> +				    guest_test_phys_mem, TEST_SLOT, TEST_NPAGES,
> +				    private ? KVM_MEM_GUEST_MEMFD : 0);
> +	virt_map(vm, guest_test_virt_mem, guest_test_phys_mem, TEST_NPAGES);