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Tue, 2 Sep 2025 11:20:16 +0000 (UTC) X-Farcaster-Flow-ID: 0dc98258-151a-46cc-81b3-dce1ed47247b Received: from EX19D022EUC002.ant.amazon.com (10.252.51.137) by EX19MTAEUB002.ant.amazon.com (10.252.51.59) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA) id 15.2.2562.17; Tue, 2 Sep 2025 11:20:16 +0000 Received: from EX19D022EUC002.ant.amazon.com (10.252.51.137) by EX19D022EUC002.ant.amazon.com (10.252.51.137) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA) id 15.2.2562.20; Tue, 2 Sep 2025 11:20:15 +0000 Received: from EX19D022EUC002.ant.amazon.com ([fe80::bd:307b:4d3a:7d80]) by EX19D022EUC002.ant.amazon.com ([fe80::bd:307b:4d3a:7d80%3]) with mapi id 15.02.2562.020; Tue, 2 Sep 2025 11:20:15 +0000 From: "Kalyazin, Nikita" To: "pbonzini@redhat.com" , "shuah@kernel.org" CC: "kvm@vger.kernel.org" , "linux-kselftest@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "michael.day@amd.com" , "david@redhat.com" , "jthoughton@google.com" , "Roy, Patrick" , "Thomson, Jack" , "Manwaring, Derek" , "Cali, Marco" , "Kalyazin, Nikita" Subject: [PATCH v5 2/2] KVM: selftests: update guest_memfd write tests Thread-Topic: [PATCH v5 2/2] KVM: selftests: update guest_memfd write tests Thread-Index: AQHcG/uOPOuTx3pVLkmJVq9l2Ktv1Q== Date: Tue, 2 Sep 2025 11:20:15 +0000 Message-ID: <20250902111951.58315-3-kalyazin@amazon.com> References: <20250902111951.58315-1-kalyazin@amazon.com> In-Reply-To: <20250902111951.58315-1-kalyazin@amazon.com> Accept-Language: en-GB, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: Content-Transfer-Encoding: quoted-printable Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" From: Nikita Kalyazin This is to reflect that the write syscall is now implemented for guest_memfd. Signed-off-by: Nikita Kalyazin --- .../testing/selftests/kvm/guest_memfd_test.c | 86 +++++++++++++++++-- 1 file changed, 80 insertions(+), 6 deletions(-) diff --git a/tools/testing/selftests/kvm/guest_memfd_test.c b/tools/testing= /selftests/kvm/guest_memfd_test.c index b3ca6737f304..1236e31f5041 100644 --- a/tools/testing/selftests/kvm/guest_memfd_test.c +++ b/tools/testing/selftests/kvm/guest_memfd_test.c @@ -24,18 +24,91 @@ #include "test_util.h" #include "ucall_common.h" =20 -static void test_file_read_write(int fd) +static void test_file_read(int fd) { char buf[64]; =20 TEST_ASSERT(read(fd, buf, sizeof(buf)) < 0, "read on a guest_mem fd should fail"); - TEST_ASSERT(write(fd, buf, sizeof(buf)) < 0, - "write on a guest_mem fd should fail"); TEST_ASSERT(pread(fd, buf, sizeof(buf), 0) < 0, "pread on a guest_mem fd should fail"); - TEST_ASSERT(pwrite(fd, buf, sizeof(buf), 0) < 0, - "pwrite on a guest_mem fd should fail"); +} + +static void test_file_write(int fd, size_t total_size) +{ + size_t page_size =3D getpagesize(); + void *buf =3D NULL; + int ret; + + ret =3D posix_memalign(&buf, page_size, total_size); + TEST_ASSERT_EQ(ret, 0); + + /* Check arguments correctness checks work as expected */ + + ret =3D pwrite(fd, buf, page_size - 1, 0); + TEST_ASSERT(ret =3D=3D -1, "write unaligned count on a guest_mem fd shoul= d fail"); + TEST_ASSERT_EQ(errno, EINVAL); + + ret =3D pwrite(fd, buf, page_size, 1); + TEST_ASSERT(ret =3D=3D -1, "write unaligned offset on a guest_mem fd shou= ld fail"); + TEST_ASSERT_EQ(errno, EINVAL); + + ret =3D pwrite(fd, buf, page_size, total_size); + TEST_ASSERT(ret =3D=3D -1, "writing past the file size on a guest_mem fd = should fail"); + TEST_ASSERT_EQ(errno, EINVAL); + + ret =3D pwrite(fd, NULL, page_size, 0); + TEST_ASSERT(ret =3D=3D -1, "supplying a NULL buffer when writing a guest_= mem fd should fail"); + TEST_ASSERT_EQ(errno, EFAULT); + + /* Check double population is not allowed */ + + ret =3D pwrite(fd, buf, page_size, 0); + TEST_ASSERT(ret =3D=3D page_size, "page-aligned write on a guest_mem fd s= hould succeed"); + + ret =3D pwrite(fd, buf, page_size, 0); + TEST_ASSERT(ret =3D=3D -1, "write on already populated guest_mem fd shoul= d fail"); + TEST_ASSERT_EQ(errno, ENOSPC); + + ret =3D fallocate(fd, FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE, 0, page= _size); + TEST_ASSERT(!ret, "fallocate(PUNCH_HOLE) should succeed"); + + /* Check population is allowed again after punching a hole */ + + ret =3D pwrite(fd, buf, page_size, 0); + TEST_ASSERT(ret =3D=3D page_size, + "page-aligned write on a punched guest_mem fd should succeed"); + + ret =3D fallocate(fd, FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE, 0, page= _size); + TEST_ASSERT(!ret, "fallocate(PUNCH_HOLE) should succeed"); + + /* Check population of already allocated memory is allowed */ + + ret =3D fallocate(fd, FALLOC_FL_KEEP_SIZE, 0, page_size); + TEST_ASSERT(!ret, "fallocate with aligned offset and size should succeed"= ); + + ret =3D pwrite(fd, buf, page_size, 0); + TEST_ASSERT(ret =3D=3D page_size, "write on a preallocated guest_mem fd s= hould succeed"); + + ret =3D fallocate(fd, FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE, 0, page= _size); + TEST_ASSERT(!ret, "fallocate(PUNCH_HOLE) should succeed"); + + /* Check population works until an already populated page is encountered = */ + + ret =3D pwrite(fd, buf, total_size, 0); + TEST_ASSERT(ret =3D=3D total_size, "page-aligned write on a guest_mem fd = should succeed"); + + ret =3D fallocate(fd, FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE, 0, page= _size); + TEST_ASSERT(!ret, "fallocate(PUNCH_HOLE) should succeed"); + + ret =3D pwrite(fd, buf, total_size, 0); + TEST_ASSERT(ret =3D=3D page_size, "write on a guest_mem fd should not ove= rwrite data"); + + ret =3D fallocate(fd, FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE, 0, tota= l_size); + TEST_ASSERT(!ret, "fallocate(PUNCH_HOLE) should succeed"); + + + free(buf); } =20 static void test_mmap_supported(int fd, size_t page_size, size_t total_siz= e) @@ -281,7 +354,8 @@ static void test_guest_memfd(unsigned long vm_type) =20 fd =3D vm_create_guest_memfd(vm, total_size, flags); =20 - test_file_read_write(fd); + test_file_read(fd); + test_file_write(fd, total_size); =20 if (flags & GUEST_MEMFD_FLAG_MMAP) { test_mmap_supported(fd, page_size, total_size); --=20 2.50.1