From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f201.google.com (mail-pl1-f201.google.com [209.85.214.201]) (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 3FEF825A2DE for ; Mon, 29 Sep 2025 18:35:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1759170911; cv=none; b=kJ/FQ15Q4bpID7KtGQBvE+gG/j2ni1SvPTAJA2F/OiXK6ZKxiC9WXyujnxiCBUTPyIDFvCD+Zf0Py5/+w9Sl/DcjHegivzRceNaDgjYiljcCCbpxkI7VxzJ1+FE5NeVfLBJfPnS1+ofniJ0pFdMDrT0GFcmjdDaOhLvO7krMqsk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1759170911; c=relaxed/simple; bh=fIIb2twrTp+ee3/m37i+hJz/W7LPccSw9IAoxQfZLoY=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=o+HJzGUfpR4LfKx7hXY1ncq+8/V0jrMWpf583ip+dj8HygNJqMEhmWsaqLtAjhd+PsnK33sZi33W4adudTzJYwEjfXBO6H7FfBABn4m/i7/ONAfui7sNnxu0pLnZzL3DFLr+W7qNZ6QNnBnlyGQVty0hZzaMKJWPqKWXFNlMrSY= 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=KbG4o0W7; arc=none smtp.client-ip=209.85.214.201 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="KbG4o0W7" Received: by mail-pl1-f201.google.com with SMTP id d9443c01a7336-277f0ea6ee6so62522885ad.0 for ; Mon, 29 Sep 2025 11:35:09 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1759170908; x=1759775708; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=cXfUqpKd6dHxyOJQiTneWF8LWJFxDmdIGTP3Vx6zlJg=; b=KbG4o0W7WwmgZDQU8+KVf3EvYxvjfG1TtzcbGxe1n+OVl4u5seagQxpxcjQjO3mKht yqwNZxGXvqrEWED6YjJD2272lhqpr3aif1aOHE0AASeb763yO6MCaj0/qrYEyuJNTB/c TgBbPHxFolJihb0JI2I7GUJWwAm9FQeCpN7nBtb7O/7hHW/TYJ6quBcRe9xoRMrl9xqk TDUNkAW9wwcbhuO5nmnsd+vnPcl6W8lnLTMMIRB097jZe3SZd5W/LZr1wqWs97dkf1GP OZv8KZl1TffOyIH36liCxW6ysJpgZZJ5nB65TRgh7U2dch+LA86WeVeu7bKFw3DXCGUt V2xw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1759170908; x=1759775708; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=cXfUqpKd6dHxyOJQiTneWF8LWJFxDmdIGTP3Vx6zlJg=; b=ECyFieRtBgR+MlePBWC/M7vLC1YIfRr7iJ6slFHmdIYnLNVAVT6HBzmozVSBjcnI2/ 6TWRdL9aBZvXqI/Dr+JQCA5PpLPcUvOXQcrxgvUDXqgoFGLnDaGhU8D7Jbt1wFZ5TcQI c5RPjUZLGFcFlmmiceaQjvbnwTDAOKMM1ORzUxoh4eCFhVsbo6NfAaqUvDcNIzIIwQmb /PGaOxVOS635tznflDnSQL0fG64+dU/nFaZofDOZ7Qmb8bhjEDBm5XJdAKBz3Lzyvnq6 3tdFzcJEGbaPkWhYFqSodl2+gLsoyQS+oeXl7hVcKoNcXHHV3gQMmc1NyljAF4+61BAq DwHA== X-Forwarded-Encrypted: i=1; AJvYcCUVIk611sCQfUfnzcpnxVQJL9tv6fq6renGhBimJ09RQTfczCOofTyNihWKZRpjfd2BmvTNlVLKjdCgOO4=@vger.kernel.org X-Gm-Message-State: AOJu0YxrDiYk3s5PXnQfUpVrYv77/onaF2TXGNiHqdsj2+69KPQnwQEY Y5ztA4R7fJTbmAJaIsUjBwiWHX3dzVI5RQUcTKqqV9UdhQ6RBZFwtMgMX1N8SVE0twsS7hJIDEt 3igGOJw== X-Google-Smtp-Source: AGHT+IH981e6NsQ3ClHJ6uiza+16E4T3EA3bY2V9J26shLo1MnL8u3/WqbuFvZSBRvr4YgYDuKyVG4B9ukA= X-Received: from plje8.prod.google.com ([2002:a17:902:ed88:b0:269:b756:8e38]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a17:903:19ce:b0:249:1234:9f7c with SMTP id d9443c01a7336-27ed4ac6238mr157088135ad.60.1759170908478; Mon, 29 Sep 2025 11:35:08 -0700 (PDT) Date: Mon, 29 Sep 2025 11:35:07 -0700 In-Reply-To: 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> <20250926163114.2626257-7-seanjc@google.com> Message-ID: Subject: Re: [PATCH 6/6] KVM: selftests: Verify that faulting in private guest_memfd memory fails From: Sean Christopherson To: Ackerley Tng Cc: Paolo Bonzini , Christian Borntraeger , Janosch Frank , Claudio Imbrenda , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, David Hildenbrand , Fuad Tabba Content-Type: text/plain; charset="us-ascii" On Mon, Sep 29, 2025, Sean Christopherson wrote: > How's this look? > > static void test_fault_sigbus(int fd, size_t accessible_size, size_t mmap_size) > { > struct sigaction sa_old, sa_new = { > .sa_handler = fault_sigbus_handler, > }; > const uint8_t val = 0xaa; > uint8_t *mem; > size_t i; > > mem = kvm_mmap(mmap_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd); > > sigaction(SIGBUS, &sa_new, &sa_old); > if (sigsetjmp(jmpbuf, 1) == 0) { > memset(mem, val, mmap_size); > TEST_FAIL("memset() should have triggered SIGBUS"); > } > if (sigsetjmp(jmpbuf, 1) == 0) { > (void)READ_ONCE(mem[accessible_size]); > TEST_FAIL("load at first unaccessible byte should have triggered SIGBUS"); > } > sigaction(SIGBUS, &sa_old, NULL); > > for (i = 0; i < accessible_size; i++) > TEST_ASSERT_EQ(READ_ONCE(mem[i]), val); > > kvm_munmap(mem, mmap_size); > } > > static void test_fault_overflow(int fd, size_t total_size) > { > test_fault_sigbus(fd, total_size, total_size * 4); > } > > static void test_fault_private(int fd, size_t total_size) > { > test_fault_sigbus(fd, 0, total_size); > } And if I don't wantonly change variable names/types, the diff is much cleaner: diff --git a/tools/testing/selftests/kvm/guest_memfd_test.c b/tools/testing/selftests/kvm/guest_memfd_test.c index 8ed08be72c43..8e375de2d7d8 100644 --- a/tools/testing/selftests/kvm/guest_memfd_test.c +++ b/tools/testing/selftests/kvm/guest_memfd_test.c @@ -83,12 +83,11 @@ void fault_sigbus_handler(int signum) siglongjmp(jmpbuf, 1); } -static void test_fault_overflow(int fd, size_t total_size) +static void test_fault_sigbus(int fd, size_t accessible_size, size_t map_size) { struct sigaction sa_old, sa_new = { .sa_handler = fault_sigbus_handler, }; - size_t map_size = total_size * 4; const char val = 0xaa; char *mem; size_t i; @@ -102,12 +101,22 @@ static void test_fault_overflow(int fd, size_t total_size) } sigaction(SIGBUS, &sa_old, NULL); - for (i = 0; i < total_size; i++) + for (i = 0; i < accessible_size; i++) TEST_ASSERT_EQ(READ_ONCE(mem[i]), val); kvm_munmap(mem, map_size); } +static void test_fault_overflow(int fd, size_t total_size) +{ + test_fault_sigbus(fd, total_size, total_size * 4); +} + +static void test_fault_private(int fd, size_t total_size) +{ + test_fault_sigbus(fd, 0, total_size); +} + static void test_mmap_not_supported(int fd, size_t total_size) { char *mem; @@ -279,10 +288,13 @@ static void __test_guest_memfd(struct kvm_vm *vm, uint64_t flags) gmem_test(file_read_write, vm, flags); - 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(mmap_cow, 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); } @@ -300,9 +312,11 @@ static void test_guest_memfd(unsigned long vm_type) __test_guest_memfd(vm, 0); - 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); + } kvm_vm_free(vm); }