From: Zongyao Chen Date: Fri, 22 May 2026 17:21:50 +0000 (-0700) Subject: KVM: selftests: Test guest_memfd binding overlap without GPA overlap X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=772989854acd17e6cc9b87c54595aba4ff002130;p=thirdparty%2Fkernel%2Flinux.git KVM: selftests: Test guest_memfd binding overlap without GPA overlap The guest_memfd binding overlap test recreates the deleted slot with GPA ranges that overlap the still-live slot. KVM rejects those attempts from the generic memslot overlap check before reaching kvm_gmem_bind(), so the test can pass even if guest_memfd binding overlap detection is broken. Recreate the slot at its original, non-overlapping GPA and use guest_memfd offsets that overlap the front and back halves of the other slot's binding. Expand the guest_memfd so the back-half case remains within the file size. Fixes: 2feabb855df8 ("KVM: selftests: Expand set_memory_region_test to validate guest_memfd()") Signed-off-by: Zongyao Chen Reviewed-by: Ackerley Tng Tested-by: Ackerley Tng [sean: keep the existing GPA overlap testcases] Link: https://patch.msgid.link/20260522172151.3530267-3-seanjc@google.com Signed-off-by: Sean Christopherson --- diff --git a/tools/testing/selftests/kvm/set_memory_region_test.c b/tools/testing/selftests/kvm/set_memory_region_test.c index 9b919a231c937..be99c1ff5a5a9 100644 --- a/tools/testing/selftests/kvm/set_memory_region_test.c +++ b/tools/testing/selftests/kvm/set_memory_region_test.c @@ -510,7 +510,7 @@ static void test_add_overlapping_private_memory_regions(void) vm = vm_create_barebones_type(KVM_X86_SW_PROTECTED_VM); - memfd = vm_create_guest_memfd(vm, MEM_REGION_SIZE * 4, 0); + memfd = vm_create_guest_memfd(vm, MEM_REGION_SIZE * 5, 0); vm_set_user_memory_region2(vm, MEM_REGION_SLOT, KVM_MEM_GUEST_MEMFD, MEM_REGION_GPA, MEM_REGION_SIZE * 2, 0, memfd, 0); @@ -526,7 +526,30 @@ static void test_add_overlapping_private_memory_regions(void) vm_set_user_memory_region2(vm, MEM_REGION_SLOT, KVM_MEM_GUEST_MEMFD, MEM_REGION_GPA, 0, NULL, -1, 0); - /* Overlap the front half of the other slot. */ + /* + * Verify that overlap in the guest_memfd bindings (i.e. in guest_memfd + * file offsets), but _not_ in the GPA space, fails with -EEXIST. + */ + r = __vm_set_user_memory_region2(vm, MEM_REGION_SLOT, KVM_MEM_GUEST_MEMFD, + MEM_REGION_GPA, + MEM_REGION_SIZE * 2, + 0, memfd, MEM_REGION_SIZE); + TEST_ASSERT(r == -1 && errno == EEXIST, + "Overlapping guest_memfd() bindings should fail with EEXIST"); + + /* And now the back half of the other slot's guest_memfd binding. */ + r = __vm_set_user_memory_region2(vm, MEM_REGION_SLOT, KVM_MEM_GUEST_MEMFD, + MEM_REGION_GPA, + MEM_REGION_SIZE * 2, + 0, memfd, MEM_REGION_SIZE * 3); + TEST_ASSERT(r == -1 && errno == EEXIST, + "Overlapping guest_memfd() bindings should fail with EEXIST"); + + /* + * Repeat the overlap tests, but this time with overlap in the memslots + * GPA space. Regardless of where there is overlap, KVM should return + * -EEXIST. + */ r = __vm_set_user_memory_region2(vm, MEM_REGION_SLOT, KVM_MEM_GUEST_MEMFD, MEM_REGION_GPA * 2 - MEM_REGION_SIZE, MEM_REGION_SIZE * 2,