From nobody Tue Dec 2 00:25:24 2025 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 53639332900; Tue, 25 Nov 2025 18:39:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764095959; cv=none; b=YOyoPlIrs/Pc+bSDMtFDSO7ymPmlO6YUKMtkYCHPcELVWVKA+dJaoPXFuMlKdBJ33eOzmHL8Nug6rt1vaSue3oR16c+N2VdmD165ghslJHh03kKIkUVZTxPHQLrbV4quJFxfdEtRNT6tkDpbHxzfD5U6KfMmrbJ9ykA/nsOQ0Jo= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764095959; c=relaxed/simple; bh=h8iM1V294GwM0YHrw7ozBTpi1JGWrn7/s48f8890vrE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=genjoyuN2jdBj4FGTv4mKvNIQuGGgnbkdfslWrg1WYA3rUcwPrHSuVVhpJsl7VBEOivXJofXAr5XRJd/qUCBihJR4THMDVF1fVpf7QkiGi4WWsyWiMimfL7RCfqUDH0T7zR3suZe6dNkqQww5GKL5xPQz1UWlkqdLxnd1jpNxtA= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=KpDwkVxx; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="KpDwkVxx" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 95AD5C4CEF1; Tue, 25 Nov 2025 18:39:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1764095958; bh=h8iM1V294GwM0YHrw7ozBTpi1JGWrn7/s48f8890vrE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=KpDwkVxxtG+c/qJ0jcnelffGjd9pZ8i28l7m24NCzRasNoczK4TLJUiC4FHrUVaCw AMm2bkuOsfFwGpAZXg7G1uz4FFGTXpegz25u6UWhwWAnGyt3SmmtayEZX9gcNA7iIs CchiL5Gq2x1uxopNFkGoDUHpdoyske5ZnY4SJjarxxF5Wqb/U15YQyXu1s2fTN5FxD m4rDkPMt5n+5oAMJ8eK5Ynyyhze9OzC8iHSXholCKVJ2nY4VQ3enOtW8kKu4pNkA5t +3vdhqEYDVoRkY27/+boIyypSnPNhybF118rh3aEMFTfx+DPijTJan3lagof8ge2Aa SE50WKNpTSC2A== From: Mike Rapoport To: linux-mm@kvack.org Cc: Andrea Arcangeli , Andrew Morton , Axel Rasmussen , Baolin Wang , David Hildenbrand , Hugh Dickins , James Houghton , "Liam R. Howlett" , Lorenzo Stoakes , Michal Hocko , Mike Rapoport , Nikita Kalyazin , Paolo Bonzini , Peter Xu , Sean Christopherson , Shuah Khan , Suren Baghdasaryan , Vlastimil Babka , linux-kernel@vger.kernel.org, kvm@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: [PATCH v2 5/5] KVM: selftests: test userfaultfd minor for guest_memfd Date: Tue, 25 Nov 2025 20:38:40 +0200 Message-ID: <20251125183840.2368510-6-rppt@kernel.org> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20251125183840.2368510-1-rppt@kernel.org> References: <20251125183840.2368510-1-rppt@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Nikita Kalyazin The test demonstrates that a minor userfaultfd event in guest_memfd can be resolved via a memcpy followed by a UFFDIO_CONTINUE ioctl. Signed-off-by: Nikita Kalyazin Co-developed-by: Mike Rapoport (Microsoft) Signed-off-by: Mike Rapoport (Microsoft) Acked-by: Liam R. Howlett --- .../testing/selftests/kvm/guest_memfd_test.c | 103 ++++++++++++++++++ 1 file changed, 103 insertions(+) diff --git a/tools/testing/selftests/kvm/guest_memfd_test.c b/tools/testing= /selftests/kvm/guest_memfd_test.c index e7d9aeb418d3..a5d3ed21d7bb 100644 --- a/tools/testing/selftests/kvm/guest_memfd_test.c +++ b/tools/testing/selftests/kvm/guest_memfd_test.c @@ -10,13 +10,17 @@ #include #include #include +#include =20 #include #include #include +#include #include #include #include +#include +#include =20 #include "kvm_util.h" #include "test_util.h" @@ -254,6 +258,104 @@ static void test_guest_memfd_flags(struct kvm_vm *vm) } } =20 +struct fault_args { + char *addr; + volatile char value; +}; + +static void *fault_thread_fn(void *arg) +{ + struct fault_args *args =3D arg; + + /* Trigger page fault */ + args->value =3D *args->addr; + return NULL; +} + +static void test_uffd_minor(int fd, size_t total_size) +{ + struct uffdio_api uffdio_api =3D { + .api =3D UFFD_API, + .features =3D UFFD_FEATURE_MINOR_GENERIC, + }; + struct uffdio_register uffd_reg; + struct uffdio_continue uffd_cont; + struct uffd_msg msg; + struct fault_args args; + pthread_t fault_thread; + void *mem, *mem_nofault, *buf =3D NULL; + int uffd, ret; + off_t offset =3D page_size; + void *fault_addr; + + ret =3D posix_memalign(&buf, page_size, total_size); + TEST_ASSERT_EQ(ret, 0); + + memset(buf, 0xaa, total_size); + + uffd =3D syscall(__NR_userfaultfd, O_CLOEXEC); + TEST_ASSERT(uffd !=3D -1, "userfaultfd creation should succeed"); + + ret =3D ioctl(uffd, UFFDIO_API, &uffdio_api); + TEST_ASSERT(ret !=3D -1, "ioctl(UFFDIO_API) should succeed"); + + mem =3D mmap(NULL, total_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0); + TEST_ASSERT(mem !=3D MAP_FAILED, "mmap should succeed"); + + mem_nofault =3D mmap(NULL, total_size, PROT_READ | PROT_WRITE, MAP_SHARED= , fd, 0); + TEST_ASSERT(mem_nofault !=3D MAP_FAILED, "mmap should succeed"); + + uffd_reg.range.start =3D (unsigned long)mem; + uffd_reg.range.len =3D total_size; + uffd_reg.mode =3D UFFDIO_REGISTER_MODE_MINOR; + ret =3D ioctl(uffd, UFFDIO_REGISTER, &uffd_reg); + TEST_ASSERT(ret !=3D -1, "ioctl(UFFDIO_REGISTER) should succeed"); + + ret =3D fallocate(fd, FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE, + offset, page_size); + TEST_ASSERT(!ret, "fallocate(PUNCH_HOLE) should succeed"); + + fault_addr =3D mem + offset; + args.addr =3D fault_addr; + + ret =3D pthread_create(&fault_thread, NULL, fault_thread_fn, &args); + TEST_ASSERT(ret =3D=3D 0, "pthread_create should succeed"); + + ret =3D read(uffd, &msg, sizeof(msg)); + TEST_ASSERT(ret !=3D -1, "read from userfaultfd should succeed"); + TEST_ASSERT(msg.event =3D=3D UFFD_EVENT_PAGEFAULT, "event type should be = pagefault"); + TEST_ASSERT((void *)(msg.arg.pagefault.address & ~(page_size - 1)) =3D=3D= fault_addr, + "pagefault should occur at expected address"); + + memcpy(mem_nofault + offset, buf + offset, page_size); + + uffd_cont.range.start =3D (unsigned long)fault_addr; + uffd_cont.range.len =3D page_size; + uffd_cont.mode =3D 0; + ret =3D ioctl(uffd, UFFDIO_CONTINUE, &uffd_cont); + TEST_ASSERT(ret !=3D -1, "ioctl(UFFDIO_CONTINUE) should succeed"); + + /* + * wait for fault_thread to finish to make sure fault happened and was + * resolved before we verify the values + */ + ret =3D pthread_join(fault_thread, NULL); + TEST_ASSERT(ret =3D=3D 0, "pthread_join should succeed"); + + TEST_ASSERT(args.value =3D=3D *(char *)(mem_nofault + offset), + "memory should contain the value that was copied"); + TEST_ASSERT(args.value =3D=3D *(char *)(mem + offset), + "no further fault is expected"); + + ret =3D munmap(mem_nofault, total_size); + TEST_ASSERT(!ret, "munmap should succeed"); + + ret =3D munmap(mem, total_size); + TEST_ASSERT(!ret, "munmap should succeed"); + free(buf); + close(uffd); +} + #define gmem_test(__test, __vm, __flags) \ do { \ int fd =3D vm_create_guest_memfd(__vm, page_size * 4, __flags); \ @@ -273,6 +375,7 @@ static void __test_guest_memfd(struct kvm_vm *vm, uint6= 4_t flags) if (flags & GUEST_MEMFD_FLAG_INIT_SHARED) { gmem_test(mmap_supported, vm, flags); gmem_test(fault_overflow, vm, flags); + gmem_test(uffd_minor, vm, flags); } else { gmem_test(fault_private, vm, flags); } --=20 2.50.1