Commit a4187c9b authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
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KVM: selftests: Split out helper to allocate guest mem via memfd 



Extract the code for allocating guest memory via memfd out of
vm_userspace_mem_region_add() and into a new helper, kvm_memfd_alloc().
A future selftest to populate a guest with the maximum amount of guest
memory will abuse KVM's memslots to alias guest memory regions to a
single memfd-backed host region, i.e. needs to back a guest with memfd
memory without a 1:1 association between a memslot and a memfd instance.

No functional change intended.

Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
Message-Id: <20220226001546.360188-27-seanjc@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 3d7d6043

tools/testing/selftests/kvm/include/kvm_util_base.h

+1 −0
Original line number Diff line number Diff line
@@ -123,6 +123,7 @@ int kvm_memcmp_hva_gva(void *hva, struct kvm_vm *vm, const vm_vaddr_t gva, 
		       size_t len);



void kvm_vm_elf_load(struct kvm_vm *vm, const char *filename);

int kvm_memfd_alloc(size_t size, bool hugepages);



void vm_dump(FILE *stream, struct kvm_vm *vm, uint8_t indent);

tools/testing/selftests/kvm/lib/kvm_util.c

+24 −18
Original line number Diff line number Diff line
@@ -718,6 +718,27 @@ void kvm_vm_free(struct kvm_vm *vmp) 
	free(vmp);

}



int kvm_memfd_alloc(size_t size, bool hugepages)

{

	int memfd_flags = MFD_CLOEXEC;

	int fd, r;



	if (hugepages)

		memfd_flags |= MFD_HUGETLB;



	fd = memfd_create("kvm_selftest", memfd_flags);

	TEST_ASSERT(fd != -1, "memfd_create() failed, errno: %i (%s)",

		    errno, strerror(errno));



	r = ftruncate(fd, size);

	TEST_ASSERT(!r, "ftruncate() failed, errno: %i (%s)", errno, strerror(errno));



	r = fallocate(fd, FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE, 0, size);

	TEST_ASSERT(!r, "fallocate() failed, errno: %i (%s)", errno, strerror(errno));



	return fd;

}



/*

 * Memory Compare, host virtual to guest virtual

 *
@@ -970,24 +991,9 @@ void vm_userspace_mem_region_add(struct kvm_vm *vm, 
		region->mmap_size += alignment;



	region->fd = -1;

	if (backing_src_is_shared(src_type)) {

		int memfd_flags = MFD_CLOEXEC;



		if (src_type == VM_MEM_SRC_SHARED_HUGETLB)

			memfd_flags |= MFD_HUGETLB;



		region->fd = memfd_create("kvm_selftest", memfd_flags);

		TEST_ASSERT(region->fd != -1,

			    "memfd_create failed, errno: %i", errno);



		ret = ftruncate(region->fd, region->mmap_size);

		TEST_ASSERT(ret == 0, "ftruncate failed, errno: %i", errno);



		ret = fallocate(region->fd,

				FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE, 0,

				region->mmap_size);

		TEST_ASSERT(ret == 0, "fallocate failed, errno: %i", errno);

	}

	if (backing_src_is_shared(src_type))

		region->fd = kvm_memfd_alloc(region->mmap_size,

					     src_type == VM_MEM_SRC_SHARED_HUGETLB);



	region->mmap_start = mmap(NULL, region->mmap_size,

				  PROT_READ | PROT_WRITE,