From nobody Wed Oct 1 23:32:09 2025 Received: from mail-pj1-f73.google.com (mail-pj1-f73.google.com [209.85.216.73]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DD51C2FB97D for ; Fri, 26 Sep 2025 16:31:31 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.216.73 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758904293; cv=none; b=PWomg7ZMWTyUaNvvK5puCU6J+kzugnfP/ljOPVGqYmsJSyVdUaDrGLx2p/Boan7ISoBgK/ssfk6FOnvMmsMPINYrU1keKuRBqJ+M0KoL6rnguhe18Mhs1eovEslmlBtsB26EGOpHwL0fw6z2xvK7Af+2SiTmwWW6qu1CorStX4M= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758904293; c=relaxed/simple; bh=DenFYgCl3E/nB8eGrwdfhtBbP3Ex8K/c68ZGtk2IY8w=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=bpN5PBsa8M6JDicT6RDELrdSjJeQdGyDoWAly5qig8u2wgXCm0EUkOah3HwV+5AfTExX+w1xdZjTZPBe1snNBX032aHKnmhVAfEvclmB324THPfejj8ZpRM+sFOrVss8IwTzKzV9k18PPlm6V5UItLVS6KSFr+QgIHHyXa9knf0= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=oj/3rMa7; arc=none smtp.client-ip=209.85.216.73 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="oj/3rMa7" Received: by mail-pj1-f73.google.com with SMTP id 98e67ed59e1d1-32df881dce2so2746370a91.2 for ; Fri, 26 Sep 2025 09:31:31 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1758904291; x=1759509091; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:from:to:cc:subject:date:message-id:reply-to; bh=NCJm+oneDJ5rwsc/098MYrhburwn9yZWwqWNnrNvoPY=; b=oj/3rMa7BQsnZekp8ZYyQ4IjlQppnoRs6VjL7MEkqoMxXD1XnUsi74PjbgZFjC3W+2 kkZu5c3gTxXU8fZXlmYdQSOS9HSdpNG+YA0MeqVsi3KcVPe5mct8zuXkHMb3piybjUIf f/wSAs2yoYFadqO1h6KM57rhdgoXDKyASIslQlHaQPNZrMo1r6YRlAXSrxGB/xhfzP8y RJFBpivc/eZ+6Uj7No3pzMg306PzUjm4gSXjNyssGzcftAmW6MHzCsHjREKFNItT96K6 yHdXjcqfRrVAAZ3xdgvOti+cTvxodvgfwJP/N/OCEAk1i+UekrsOWYd79iaN+4+MCt84 c8Eg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1758904291; x=1759509091; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=NCJm+oneDJ5rwsc/098MYrhburwn9yZWwqWNnrNvoPY=; b=uWYoKt/fWHnoPy3FPRIdyojAloJnEIAI06/EmAO9FdGQL1OvbYG/oXHQL0KQpUkLpJ YN6BNzCGhFvIFMRv2LIkZL5oDA+70MhEcU/NqripH6sDiR1I46QVGpylcTiiK9ZUb2er qhdS41aoRpBIRzs1k1S5kJt+lKH3YFR02oTSJzgLD+LFs0+FHijk8tGvAgI0UCHsEBib 5iDkxr1q4IH4QG9g28KBe+6fTnbbY2ucA1869vGz+/ruU5n2SUX6d7eNIgIJM3SbURIT izVYfe6+VqdVRq+oUSo+ByANlID5Sbkg2jKFKmEKnPvE9yz/TBwwEiRN0DMQlbtjAXJV sKgw== X-Forwarded-Encrypted: i=1; AJvYcCUgJzLcjyUdSj9t+NosLCMz5IMmD/UtWwy/kNfi5BT7Vo3SXliNTpnuKHjvbYTCIUis0oWvoRi5wmyLUGU=@vger.kernel.org X-Gm-Message-State: AOJu0Yx6vjqb7DXoyWzmiztfXdFL517gC3lOHbpZFYM/76hEe17VfQKH opDZPqyVtT/R+BZ0KKgU/tuWhnxf5BmwIQej45jXTRfQnTr/wKP+d4Y0asN90kmmpRsOPDQJNu+ wF9WEsg== X-Google-Smtp-Source: AGHT+IEcjS8XYUaIxvLwGVIG6V9ayVItEqtASIL24S1Lw4LUyDHuVM8ZHEEBRAHizK6NEBTV8/u3Tvd2yLk= X-Received: from pjhk88.prod.google.com ([2002:a17:90a:4ce1:b0:323:25d2:22db]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a17:90b:38ca:b0:335:2a00:6836 with SMTP id 98e67ed59e1d1-3352a00692bmr4201028a91.18.1758904291403; Fri, 26 Sep 2025 09:31:31 -0700 (PDT) Reply-To: Sean Christopherson Date: Fri, 26 Sep 2025 09:31:07 -0700 In-Reply-To: <20250926163114.2626257-1-seanjc@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20250926163114.2626257-1-seanjc@google.com> X-Mailer: git-send-email 2.51.0.536.g15c5d4f767-goog Message-ID: <20250926163114.2626257-7-seanjc@google.com> Subject: [PATCH 6/6] KVM: selftests: Verify that faulting in private guest_memfd memory fails From: Sean Christopherson To: Paolo Bonzini , Christian Borntraeger , Janosch Frank , Claudio Imbrenda Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, David Hildenbrand , Fuad Tabba , Sean Christopherson , Ackerley Tng Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Add a guest_memfd testcase to verify that faulting in private memory gets a SIGBUS. For now, test only the case where memory is private by default since KVM doesn't yet support in-place conversion. Cc: Ackerley Tng Signed-off-by: Sean Christopherson Reviewed-by: Ackerley Tng Reviewed-by: David Hildenbrand Reviewed-by: Fuad Tabba Tested-by: Fuad Tabba --- .../testing/selftests/kvm/guest_memfd_test.c | 62 ++++++++++++++----- 1 file changed, 46 insertions(+), 16 deletions(-) diff --git a/tools/testing/selftests/kvm/guest_memfd_test.c b/tools/testing= /selftests/kvm/guest_memfd_test.c index 5dd40b77dc07..b5a631aca933 100644 --- a/tools/testing/selftests/kvm/guest_memfd_test.c +++ b/tools/testing/selftests/kvm/guest_memfd_test.c @@ -40,17 +40,26 @@ static void test_file_read_write(int fd, size_t total_s= ize) "pwrite on a guest_mem fd should fail"); } =20 -static void test_mmap_supported(int fd, size_t total_size) +static void *test_mmap_common(int fd, size_t size) { - const char val =3D 0xaa; - char *mem; - size_t i; - int ret; + void *mem; =20 - mem =3D mmap(NULL, total_size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0= ); + mem =3D mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0); TEST_ASSERT(mem =3D=3D MAP_FAILED, "Copy-on-write not allowed by guest_me= mfd."); =20 - mem =3D kvm_mmap(total_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd); + mem =3D kvm_mmap(size, PROT_READ | PROT_WRITE, MAP_SHARED, fd); + + return mem; +} + +static void test_mmap_supported(int fd, size_t total_size) +{ + const char val =3D 0xaa; + char *mem; + size_t i; + int ret; + + mem =3D test_mmap_common(fd, total_size); =20 memset(mem, val, total_size); for (i =3D 0; i < total_size; i++) @@ -78,31 +87,47 @@ void fault_sigbus_handler(int signum) siglongjmp(jmpbuf, 1); } =20 -static void test_fault_overflow(int fd, size_t total_size) +static void *test_fault_sigbus(int fd, size_t size) { struct sigaction sa_old, sa_new =3D { .sa_handler =3D fault_sigbus_handler, }; - size_t map_size =3D total_size * 4; - const char val =3D 0xaa; - char *mem; - size_t i; + void *mem; =20 - mem =3D kvm_mmap(map_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd); + mem =3D test_mmap_common(fd, size); =20 sigaction(SIGBUS, &sa_new, &sa_old); if (sigsetjmp(jmpbuf, 1) =3D=3D 0) { - memset(mem, 0xaa, map_size); + memset(mem, 0xaa, size); TEST_ASSERT(false, "memset() should have triggered SIGBUS."); } sigaction(SIGBUS, &sa_old, NULL); =20 + return mem; +} + +static void test_fault_overflow(int fd, size_t total_size) +{ + size_t map_size =3D total_size * 4; + const char val =3D 0xaa; + char *mem; + size_t i; + + mem =3D test_fault_sigbus(fd, map_size); + for (i =3D 0; i < total_size; i++) TEST_ASSERT_EQ(READ_ONCE(mem[i]), val); =20 kvm_munmap(mem, map_size); } =20 +static void test_fault_private(int fd, size_t total_size) +{ + void *mem =3D test_fault_sigbus(fd, total_size); + + kvm_munmap(mem, total_size); +} + static void test_mmap_not_supported(int fd, size_t total_size) { char *mem; @@ -274,9 +299,12 @@ static void __test_guest_memfd(struct kvm_vm *vm, uint= 64_t flags) =20 gmem_test(file_read_write, vm, flags); =20 - if (flags & GUEST_MEMFD_FLAG_MMAP) { + if (flags & GUEST_MEMFD_FLAG_MMAP && + flags & GUEST_MEMFD_FLAG_DEFAULT_SHARED) { gmem_test(mmap_supported, vm, flags); gmem_test(fault_overflow, vm, flags); + } else if (flags & GUEST_MEMFD_FLAG_MMAP) { + gmem_test(fault_private, vm, flags); } else { gmem_test(mmap_not_supported, vm, flags); } @@ -294,9 +322,11 @@ static void test_guest_memfd(unsigned long vm_type) =20 __test_guest_memfd(vm, 0); =20 - if (vm_check_cap(vm, KVM_CAP_GUEST_MEMFD_MMAP)) + if (vm_check_cap(vm, KVM_CAP_GUEST_MEMFD_MMAP)) { + __test_guest_memfd(vm, GUEST_MEMFD_FLAG_MMAP); __test_guest_memfd(vm, GUEST_MEMFD_FLAG_MMAP | GUEST_MEMFD_FLAG_DEFAULT_SHARED); + } =20 kvm_vm_free(vm); } --=20 2.51.0.536.g15c5d4f767-goog