Ackerley Tng ackerleytng@google.com writes:
From: Sean Christopherson seanjc@google.com
Accept gmem_flags in vm_mem_add() to be able to create a guest_memfd within vm_mem_add().
When vm_mem_add() is used to set up a guest_memfd for a memslot, set up the provided (or created) gmem_fd as the fd for the user memory region. This makes it available to be mmap()-ed from just like fds from other memory sources. mmap() from guest_memfd using the provided gmem_flags and gmem_offset.
Add a kvm_slot_to_fd() helper to provide convenient access to the file descriptor of a memslot.
Update existing callers of vm_mem_add() to pass 0 for gmem_flags to preserve existing behavior.
Signed-off-by: Sean Christopherson seanjc@google.com [For guest_memfds, mmap() using gmem_offset instead of 0 all the time.] Signed-off-by: Ackerley Tng ackerleytng@google.com
tools/testing/selftests/kvm/include/kvm_util.h | 7 ++++++- tools/testing/selftests/kvm/lib/kvm_util.c | 18 ++++++++++-------- .../kvm/x86/private_mem_conversions_test.c | 2 +- 3 files changed, 17 insertions(+), 10 deletions(-)
[...snip...]
@@ -1050,13 +1049,16 @@ void vm_mem_add(struct kvm_vm *vm, enum vm_mem_backing_src_type src_type, } region->fd = -1;
- if (backing_src_is_shared(src_type))
- if (flags & KVM_MEM_GUEST_MEMFD && gmem_flags & GUEST_MEMFD_FLAG_MMAP)
region->fd = kvm_dup(gmem_fd);- else if (backing_src_is_shared(src_type)) region->fd = kvm_memfd_alloc(region->mmap_size, src_type == VM_MEM_SRC_SHARED_HUGETLB);
Doing this makes it hard to test the legacy dual-backing case.
It actually broke x86/private_mem_conversions_test for the legacy dual-backing case because there's no way to mmap or provide a userspace_address from the memory provider that is not guest_memfd, as determined by src_type.
I didn't test the legacy dual-backing case before posting this RFC and probably should have.
- region->mmap_start = kvm_mmap(region->mmap_size, PROT_READ | PROT_WRITE,
vm_mem_backing_src_alias(src_type)->flag,region->fd);
- mmap_offset = flags & KVM_MEM_GUEST_MEMFD ? gmem_offset : 0;
- region->mmap_start = __kvm_mmap(region->mmap_size, PROT_READ | PROT_WRITE,
vm_mem_backing_src_alias(src_type)->flag,region->fd, mmap_offset);TEST_ASSERT(!is_backing_src_hugetlb(src_type) || region->mmap_start == align_ptr_up(region->mmap_start, backing_src_pagesz), @@ -1117,7 +1119,7 @@ void vm_userspace_mem_region_add(struct kvm_vm *vm, uint64_t gpa, uint32_t slot, uint64_t npages, uint32_t flags) {
- vm_mem_add(vm, src_type, gpa, slot, npages, flags, -1, 0);
- vm_mem_add(vm, src_type, gpa, slot, npages, flags, -1, 0, 0);
} /* diff --git a/tools/testing/selftests/kvm/x86/private_mem_conversions_test.c b/tools/testing/selftests/kvm/x86/private_mem_conversions_test.c index 1969f4ab9b280..41f6b38f04071 100644 --- a/tools/testing/selftests/kvm/x86/private_mem_conversions_test.c +++ b/tools/testing/selftests/kvm/x86/private_mem_conversions_test.c @@ -399,7 +399,7 @@ static void test_mem_conversions(enum vm_mem_backing_src_type src_type, uint32_t for (i = 0; i < nr_memslots; i++) vm_mem_add(vm, src_type, BASE_DATA_GPA + slot_size * i, BASE_DATA_SLOT + i, slot_size / vm->page_size,
KVM_MEM_GUEST_MEMFD, memfd, slot_size * i);
KVM_MEM_GUEST_MEMFD, memfd, slot_size * i, 0);for (i = 0; i < nr_vcpus; i++) { uint64_t gpa = BASE_DATA_GPA + i * per_cpu_size; -- 2.51.0.858.gf9c4a03a3a-goog