From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 5F381CC6B01 for ; Thu, 2 Apr 2026 04:13:52 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id BF8D16B00AD; Thu, 2 Apr 2026 00:13:51 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id BD0F46B00AF; Thu, 2 Apr 2026 00:13:51 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id B0D726B00B0; Thu, 2 Apr 2026 00:13:51 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id A37B46B00AD for ; Thu, 2 Apr 2026 00:13:51 -0400 (EDT) Received: from smtpin25.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay05.hostedemail.com (Postfix) with ESMTP id 4468D58A9C for ; Thu, 2 Apr 2026 04:13:51 +0000 (UTC) X-FDA: 84612297462.25.4FF69C2 Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf13.hostedemail.com (Postfix) with ESMTP id 875CD20007 for ; Thu, 2 Apr 2026 04:13:49 +0000 (UTC) Authentication-Results: imf13.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=J3swZE2Y; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf13.hostedemail.com: domain of rppt@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=rppt@kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1775103229; a=rsa-sha256; cv=none; b=agQWnymEECcyhdZv/qr1KZIchtjz5oxvN98RdDe3IVmx5yyVyRHat840lPHfUrigk9kV0O hZMgW35dJFsQzPa+30r1U9edTfcYjYmzkYmQgLHLqp9eEjDKDdFVZ7JSTW434ksfDzEi/R cPsJwYLVtjIjFBQL2OtLixA7aB5Il9A= ARC-Authentication-Results: i=1; imf13.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=J3swZE2Y; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf13.hostedemail.com: domain of rppt@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=rppt@kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1775103229; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=awGkkm2OWaLy5ex/oeihGcD8JB0EhmX9CKfQ3dh92HI=; b=5dFouzX8X+Qj7/vlRKI4doVtKoE6SfEWLQ5vMN0W8507FIh5hsvykvxAxKvDPOTj4pdG6N QJ+pzRBkuyv8YMyRO5cKNgHr71Pm9GGxV7yhUYq4MeQl8oqJWnH6GIi+dw4WfRaD78Kjup R/uShdNXvTlwjddqS8xysnkr7WAMv3M= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id 96FBD43DF9; Thu, 2 Apr 2026 04:13:48 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 37256C19423; Thu, 2 Apr 2026 04:13:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1775103228; bh=z+HQ68nm/PN2NlXH0rkdfjkI55JODdIviAntTrnHsgk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=J3swZE2YyH+2pVU1N5DjDD0TDSZ1KNCz6a4Nu7f6LjmQzi0SwxCUvgzT5USIMVc9X BgSZs0ognCJH2fM7GMkGPxOQ6ozAUdeZZOM4Im2vQOWQp5udB+LyEss9fBrJeZ2+N+ kvzlxOjYOJh/UAmNuJMoF02Gu4ey/B6DEVvfzWqpsdPBjIRBEIu09fEE7Zt7xmtiEA olaAmOrM1jgq5/OIe3GLLQ6FIS4cqOgT+KTV8MOy09Wi0YfV6WVZvX52QkSC6tNn3+ PEObeLaOxTOGniECbLzDzzPSmCul9xI4ymX3Aacbun+ZL5oyTFkO+T9imVEdL+WUZh BToHP/KPtvuyQ== From: Mike Rapoport To: Andrew Morton Cc: Andrea Arcangeli , Andrei Vagin , Axel Rasmussen , Baolin Wang , David Hildenbrand , Harry Yoo , Hugh Dickins , James Houghton , "Liam R. Howlett" , "Lorenzo Stoakes (Oracle)" , "Matthew Wilcox (Oracle)" , Michal Hocko , Mike Rapoport , Muchun Song , Nikita Kalyazin , Oscar Salvador , Paolo Bonzini , Peter Xu , Sean Christopherson , Shuah Khan , Suren Baghdasaryan , Vlastimil Babka , kvm@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH v4 15/15] KVM: selftests: test userfaultfd missing for guest_memfd Date: Thu, 2 Apr 2026 07:11:56 +0300 Message-ID: <20260402041156.1377214-16-rppt@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260402041156.1377214-1-rppt@kernel.org> References: <20260402041156.1377214-1-rppt@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Stat-Signature: sba8a5idixd9ud6wd95zbqirkpw4wsrb X-Rspamd-Queue-Id: 875CD20007 X-Rspam-User: X-Rspamd-Server: rspam03 X-HE-Tag: 1775103229-135893 X-HE-Meta: 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 8cPFSvnF Z/qiIvzqQy9r2/A0AgJcGKjXQaijens59fuOSVVmvgafvsWeiHEYQXELILfPE05rc16CA77mRPCE2U69EmBBeDaqSlIWl6FUQ9dFpP3lBLL/sCQ/uXbXuKvnhgtHJ3t3vsxtAYeQ+LJ2BNcZFl3Xk2Kp2t9xVeaowxRSZ+z33wOAZ5fRIItaO8wsrY/tGa/3TS2cNSzStEyDRVD09PjwFDrddRfgMz0IRsFWRWTmMt69RgFtUQcX7cDe2jBFd2oiYSySUnkXTg7bzPksTVdgLTR+G0BBUGBATdQKO9h0XkOruW3zUNtZsxTI0Ow== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: From: Nikita Kalyazin The test demonstrates that a missing userfaultfd event in guest_memfd can be resolved via a UFFDIO_COPY ioctl. Signed-off-by: Nikita Kalyazin Signed-off-by: Mike Rapoport (Microsoft) --- .../testing/selftests/kvm/guest_memfd_test.c | 80 ++++++++++++++++++- 1 file changed, 79 insertions(+), 1 deletion(-) diff --git a/tools/testing/selftests/kvm/guest_memfd_test.c b/tools/testing/selftests/kvm/guest_memfd_test.c index 29f8d686c09f..eb29ee5d2991 100644 --- a/tools/testing/selftests/kvm/guest_memfd_test.c +++ b/tools/testing/selftests/kvm/guest_memfd_test.c @@ -439,6 +439,82 @@ static void test_uffd_minor(int fd, size_t total_size) close(uffd); } +static void test_uffd_missing(int fd, size_t total_size) +{ + struct uffdio_register uffd_reg; + struct uffdio_copy uffd_copy; + struct uffd_msg msg; + struct fault_args args; + pthread_t fault_thread; + void *mem, *buf = NULL; + int uffd, ret; + off_t offset = page_size; + void *fault_addr; + const char test_val = 0xab; + + ret = posix_memalign(&buf, page_size, total_size); + TEST_ASSERT_EQ(ret, 0); + memset(buf, test_val, total_size); + + uffd = syscall(__NR_userfaultfd, O_CLOEXEC); + TEST_ASSERT(uffd != -1, "userfaultfd creation should succeed"); + + struct uffdio_api uffdio_api = { + .api = UFFD_API, + .features = 0, + }; + ret = ioctl(uffd, UFFDIO_API, &uffdio_api); + TEST_ASSERT(ret != -1, "ioctl(UFFDIO_API) should succeed"); + + mem = mmap(NULL, total_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0); + TEST_ASSERT(mem != MAP_FAILED, "mmap should succeed"); + + uffd_reg.range.start = (unsigned long)mem; + uffd_reg.range.len = total_size; + uffd_reg.mode = UFFDIO_REGISTER_MODE_MISSING; + ret = ioctl(uffd, UFFDIO_REGISTER, &uffd_reg); + TEST_ASSERT(ret != -1, "ioctl(UFFDIO_REGISTER) should succeed"); + + fault_addr = mem + offset; + args.addr = fault_addr; + + ret = pthread_create(&fault_thread, NULL, fault_thread_fn, &args); + TEST_ASSERT(ret == 0, "pthread_create should succeed"); + + ret = read(uffd, &msg, sizeof(msg)); + TEST_ASSERT(ret != -1, "read from userfaultfd should succeed"); + TEST_ASSERT(msg.event == UFFD_EVENT_PAGEFAULT, "event type should be pagefault"); + TEST_ASSERT((void *)(msg.arg.pagefault.address & ~(page_size - 1)) == fault_addr, + "pagefault should occur at expected address"); + TEST_ASSERT(!(msg.arg.pagefault.flags & UFFD_PAGEFAULT_FLAG_WP), + "pagefault should not be write-protect"); + + uffd_copy.dst = (unsigned long)fault_addr; + uffd_copy.src = (unsigned long)(buf + offset); + uffd_copy.len = page_size; + uffd_copy.mode = 0; + ret = ioctl(uffd, UFFDIO_COPY, &uffd_copy); + TEST_ASSERT(ret != -1, "ioctl(UFFDIO_COPY) should succeed"); + + /* Wait for the faulting thread to complete - this provides the memory barrier */ + ret = pthread_join(fault_thread, NULL); + TEST_ASSERT(ret == 0, "pthread_join should succeed"); + + /* + * Now it's safe to check args.value - the thread has completed + * and memory is synchronized + */ + TEST_ASSERT(args.value == test_val, + "memory should contain the value that was copied"); + TEST_ASSERT(*(char *)(mem + offset) == test_val, + "no further fault is expected"); + + ret = munmap(mem, total_size); + TEST_ASSERT(!ret, "munmap should succeed"); + free(buf); + close(uffd); +} + static void test_guest_memfd_flags(struct kvm_vm *vm) { uint64_t valid_flags = vm_check_cap(vm, KVM_CAP_GUEST_MEMFD_FLAGS); @@ -494,8 +570,10 @@ static void __test_guest_memfd(struct kvm_vm *vm, uint64_t flags) gmem_test(fallocate, vm, flags); gmem_test(invalid_punch_hole, vm, flags); - if (flags & GUEST_MEMFD_FLAG_INIT_SHARED) + if (flags & GUEST_MEMFD_FLAG_INIT_SHARED) { gmem_test(uffd_minor, vm, flags); + gmem_test(uffd_missing, vm, flags); + } } static void test_guest_memfd(unsigned long vm_type) -- 2.53.0