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 X-Spam-Level: X-Spam-Status: No, score=-13.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 12BBEC4361B for ; Mon, 14 Dec 2020 11:03:52 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 3FCAC207B0 for ; Mon, 14 Dec 2020 11:03:50 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3FCAC207B0 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:38886 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1koldt-0005q1-W0 for qemu-devel@archiver.kernel.org; Mon, 14 Dec 2020 06:03:50 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:50732) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kolcK-0005Mw-Rf for qemu-devel@nongnu.org; Mon, 14 Dec 2020 06:02:12 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:37906) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1kolcG-0006DO-9r for qemu-devel@nongnu.org; Mon, 14 Dec 2020 06:02:10 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1607943726; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=4qKeBdQAVaRLp0OddqZbG5LYByApk1UJjkcKbD4bJwQ=; b=XBG8Xe1f/Iyv57aGOZ0cO6wV0eBfruliRGMLbnk5vLPW36/gwWgEY7a1km1qaqU8qzBqgY FQiAIx5dmbXIb7/+HANcNyDoMRqkx98KIaSJfXZl6WoswuK2Fhgxk5F7dtlqWtuoJzGjAK WVvU1Sro+LKpTMYoYIxCVs/WNiS24eI= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-482-Fm7S-6ZbPVCy9QcaExctSA-1; Mon, 14 Dec 2020 06:02:01 -0500 X-MC-Unique: Fm7S-6ZbPVCy9QcaExctSA-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 636C2192CC41; Mon, 14 Dec 2020 11:02:00 +0000 (UTC) Received: from localhost (unknown [10.40.208.9]) by smtp.corp.redhat.com (Postfix) with ESMTP id 6D5205D9D0; Mon, 14 Dec 2020 11:01:51 +0000 (UTC) Date: Mon, 14 Dec 2020 12:01:49 +0100 From: Igor Mammedov To: Stefan Hajnoczi Subject: Re: [PATCH v2 1/3] memory: add readonly support to memory_region_init_ram_from_file() Message-ID: <20201214120149.4fb0835f@redhat.com> In-Reply-To: <20200916095150.755714-2-stefanha@redhat.com> References: <20200916095150.755714-1-stefanha@redhat.com> <20200916095150.755714-2-stefanha@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=imammedo@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Received-SPF: pass client-ip=63.128.21.124; envelope-from=imammedo@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=-0.01, RCVD_IN_MSPIKE_WL=-0.01, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Eduardo Habkost , "Michael S. Tsirkin" , Julio Montes , Xiao Guangrong , qemu-devel@nongnu.org, eric.g.ernst@gmail.com, Paolo Bonzini , Philippe =?UTF-8?B?TWF0aGlldS1EYXVkw4PCqQ==?= , Richard Henderson Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Wed, 16 Sep 2020 10:51:48 +0100 Stefan Hajnoczi wrote: > There is currently no way to open(O_RDONLY) and mmap(PROT_READ) when > creating a memory region from a file. This functionality is needed since > the underlying host file may not allow writing. >=20 > Add a bool readonly argument to memory_region_init_ram_from_file() and > the APIs it calls. >=20 > Extend memory_region_init_ram_from_file() rather than introducing a > memory_region_init_rom_from_file() API so that callers can easily make a > choice between read/write and read-only at runtime without calling > different APIs. >=20 > No new RAMBlock flag is introduced for read-only because it's unclear > whether RAMBlocks need to know that they are read-only. Pass a bool > readonly argument instead. >=20 > Both of these design decisions can be changed in the future. It just > seemed like the simplest approach to me. >=20 > Acked-by: Michael S. Tsirkin > Reviewed-by: Philippe Mathieu-Daud=C3=83=C2=A9 > Signed-off-by: Stefan Hajnoczi Reviewed-by: Igor Mammedov > --- > include/exec/memory.h | 2 ++ > include/exec/ram_addr.h | 5 +++-- > include/qemu/mmap-alloc.h | 2 ++ > backends/hostmem-file.c | 2 +- > exec.c | 18 +++++++++++------- > softmmu/memory.c | 7 +++++-- > util/mmap-alloc.c | 10 ++++++---- > util/oslib-posix.c | 2 +- > 8 files changed, 31 insertions(+), 17 deletions(-) >=20 > diff --git a/include/exec/memory.h b/include/exec/memory.h > index f1bb2a7df5..a81fa26165 100644 > --- a/include/exec/memory.h > +++ b/include/exec/memory.h > @@ -879,6 +879,7 @@ void memory_region_init_resizeable_ram(MemoryRegion *= mr, > * - RAM_PMEM: the memory is persistent memory > * Other bits are ignored now. > * @path: the path in which to allocate the RAM. > + * @readonly: true to open @path for reading, false for read/write. > * @errp: pointer to Error*, to store an error if it happens. > * > * Note that this function does not do anything to cause the data in the > @@ -891,6 +892,7 @@ void memory_region_init_ram_from_file(MemoryRegion *m= r, > uint64_t align, > uint32_t ram_flags, > const char *path, > + bool readonly, > Error **errp); > =20 > /** > diff --git a/include/exec/ram_addr.h b/include/exec/ram_addr.h > index 3ef729a23c..2a0360a0f2 100644 > --- a/include/exec/ram_addr.h > +++ b/include/exec/ram_addr.h > @@ -110,6 +110,7 @@ long qemu_maxrampagesize(void); > * - RAM_PMEM: the backend @mem_path or @fd is persistent m= emory > * Other bits are ignored. > * @mem_path or @fd: specify the backing file or device > + * @readonly: true to open @path for reading, false for read/write. > * @errp: pointer to Error*, to store an error if it happens > * > * Return: > @@ -118,9 +119,9 @@ long qemu_maxrampagesize(void); > */ > RAMBlock *qemu_ram_alloc_from_file(ram_addr_t size, MemoryRegion *mr, > uint32_t ram_flags, const char *mem_p= ath, > - Error **errp); > + bool readonly, Error **errp); > RAMBlock *qemu_ram_alloc_from_fd(ram_addr_t size, MemoryRegion *mr, > - uint32_t ram_flags, int fd, > + uint32_t ram_flags, int fd, bool readon= ly, > Error **errp); > =20 > RAMBlock *qemu_ram_alloc_from_ptr(ram_addr_t size, void *host, > diff --git a/include/qemu/mmap-alloc.h b/include/qemu/mmap-alloc.h > index e786266b92..8b7a5c70f3 100644 > --- a/include/qemu/mmap-alloc.h > +++ b/include/qemu/mmap-alloc.h > @@ -14,6 +14,7 @@ size_t qemu_mempath_getpagesize(const char *mem_path); > * @size: the number of bytes to be mmaped > * @align: if not zero, specify the alignment of the starting mapping a= ddress; > * otherwise, the alignment in use will be determined by QEMU. > + * @readonly: true for a read-only mapping, false for read/write. > * @shared: map has RAM_SHARED flag. > * @is_pmem: map has RAM_PMEM flag. > * > @@ -24,6 +25,7 @@ size_t qemu_mempath_getpagesize(const char *mem_path); > void *qemu_ram_mmap(int fd, > size_t size, > size_t align, > + bool readonly, > bool shared, > bool is_pmem); > =20 > diff --git a/backends/hostmem-file.c b/backends/hostmem-file.c > index a3b2e8209e..dffdf142e0 100644 > --- a/backends/hostmem-file.c > +++ b/backends/hostmem-file.c > @@ -58,7 +58,7 @@ file_backend_memory_alloc(HostMemoryBackend *backend, E= rror **errp) > backend->size, fb->align, > (backend->share ? RAM_SHARED : 0) | > (fb->is_pmem ? RAM_PMEM : 0), > - fb->mem_path, errp); > + fb->mem_path, false, errp); > g_free(name); > #endif > } > diff --git a/exec.c b/exec.c > index e34b602bdf..f1e82dad7a 100644 > --- a/exec.c > +++ b/exec.c > @@ -1770,6 +1770,7 @@ static int64_t get_file_align(int fd) > =20 > static int file_ram_open(const char *path, > const char *region_name, > + bool readonly, > bool *created, > Error **errp) > { > @@ -1780,7 +1781,7 @@ static int file_ram_open(const char *path, > =20 > *created =3D false; > for (;;) { > - fd =3D open(path, O_RDWR); > + fd =3D open(path, readonly ? O_RDONLY : O_RDWR); > if (fd >=3D 0) { > /* @path names an existing file, use it */ > break; > @@ -1832,6 +1833,7 @@ static int file_ram_open(const char *path, > static void *file_ram_alloc(RAMBlock *block, > ram_addr_t memory, > int fd, > + bool readonly, > bool truncate, > Error **errp) > { > @@ -1882,7 +1884,7 @@ static void *file_ram_alloc(RAMBlock *block, > perror("ftruncate"); > } > =20 > - area =3D qemu_ram_mmap(fd, memory, block->mr->align, > + area =3D qemu_ram_mmap(fd, memory, block->mr->align, readonly, > block->flags & RAM_SHARED, block->flags & RAM_P= MEM); > if (area =3D=3D MAP_FAILED) { > error_setg_errno(errp, errno, > @@ -2314,7 +2316,7 @@ static void ram_block_add(RAMBlock *new_block, Erro= r **errp, bool shared) > =20 > #ifdef CONFIG_POSIX > RAMBlock *qemu_ram_alloc_from_fd(ram_addr_t size, MemoryRegion *mr, > - uint32_t ram_flags, int fd, > + uint32_t ram_flags, int fd, bool readon= ly, > Error **errp) > { > RAMBlock *new_block; > @@ -2368,7 +2370,8 @@ RAMBlock *qemu_ram_alloc_from_fd(ram_addr_t size, M= emoryRegion *mr, > new_block->used_length =3D size; > new_block->max_length =3D size; > new_block->flags =3D ram_flags; > - new_block->host =3D file_ram_alloc(new_block, size, fd, !file_size, = errp); > + new_block->host =3D file_ram_alloc(new_block, size, fd, readonly, > + !file_size, errp); > if (!new_block->host) { > g_free(new_block); > return NULL; > @@ -2387,18 +2390,19 @@ RAMBlock *qemu_ram_alloc_from_fd(ram_addr_t size,= MemoryRegion *mr, > =20 > RAMBlock *qemu_ram_alloc_from_file(ram_addr_t size, MemoryRegion *mr, > uint32_t ram_flags, const char *mem_p= ath, > - Error **errp) > + bool readonly, Error **errp) > { > int fd; > bool created; > RAMBlock *block; > =20 > - fd =3D file_ram_open(mem_path, memory_region_name(mr), &created, err= p); > + fd =3D file_ram_open(mem_path, memory_region_name(mr), readonly, &cr= eated, > + errp); > if (fd < 0) { > return NULL; > } > =20 > - block =3D qemu_ram_alloc_from_fd(size, mr, ram_flags, fd, errp); > + block =3D qemu_ram_alloc_from_fd(size, mr, ram_flags, fd, readonly, = errp); > if (!block) { > if (created) { > unlink(mem_path); > diff --git a/softmmu/memory.c b/softmmu/memory.c > index d030eb6f7c..1b0d1d42c6 100644 > --- a/softmmu/memory.c > +++ b/softmmu/memory.c > @@ -1553,15 +1553,18 @@ void memory_region_init_ram_from_file(MemoryRegio= n *mr, > uint64_t align, > uint32_t ram_flags, > const char *path, > + bool readonly, > Error **errp) > { > Error *err =3D NULL; > memory_region_init(mr, owner, name, size); > mr->ram =3D true; > + mr->readonly =3D readonly; > mr->terminates =3D true; > mr->destructor =3D memory_region_destructor_ram; > mr->align =3D align; > - mr->ram_block =3D qemu_ram_alloc_from_file(size, mr, ram_flags, path= , &err); > + mr->ram_block =3D qemu_ram_alloc_from_file(size, mr, ram_flags, path= , > + readonly, &err); > mr->dirty_log_mask =3D tcg_enabled() ? (1 << DIRTY_MEMORY_CODE) : 0; > if (err) { > mr->size =3D int128_zero(); > @@ -1585,7 +1588,7 @@ void memory_region_init_ram_from_fd(MemoryRegion *m= r, > mr->destructor =3D memory_region_destructor_ram; > mr->ram_block =3D qemu_ram_alloc_from_fd(size, mr, > share ? RAM_SHARED : 0, > - fd, &err); > + fd, false, &err); > mr->dirty_log_mask =3D tcg_enabled() ? (1 << DIRTY_MEMORY_CODE) : 0; > if (err) { > mr->size =3D int128_zero(); > diff --git a/util/mmap-alloc.c b/util/mmap-alloc.c > index 27dcccd8ec..890fda6a35 100644 > --- a/util/mmap-alloc.c > +++ b/util/mmap-alloc.c > @@ -85,9 +85,11 @@ size_t qemu_mempath_getpagesize(const char *mem_path) > void *qemu_ram_mmap(int fd, > size_t size, > size_t align, > + bool readonly, > bool shared, > bool is_pmem) > { > + int prot; > int flags; > int map_sync_flags =3D 0; > int guardfd; > @@ -146,8 +148,9 @@ void *qemu_ram_mmap(int fd, > =20 > offset =3D QEMU_ALIGN_UP((uintptr_t)guardptr, align) - (uintptr_t)gu= ardptr; > =20 > - ptr =3D mmap(guardptr + offset, size, PROT_READ | PROT_WRITE, > - flags | map_sync_flags, fd, 0); > + prot =3D PROT_READ | (readonly ? 0 : PROT_WRITE); > + > + ptr =3D mmap(guardptr + offset, size, prot, flags | map_sync_flags, = fd, 0); > =20 > if (ptr =3D=3D MAP_FAILED && map_sync_flags) { > if (errno =3D=3D ENOTSUP) { > @@ -171,8 +174,7 @@ void *qemu_ram_mmap(int fd, > * if map failed with MAP_SHARED_VALIDATE | MAP_SYNC, > * we will remove these flags to handle compatibility. > */ > - ptr =3D mmap(guardptr + offset, size, PROT_READ | PROT_WRITE, > - flags, fd, 0); > + ptr =3D mmap(guardptr + offset, size, prot, flags, fd, 0); > } > =20 > if (ptr =3D=3D MAP_FAILED) { > diff --git a/util/oslib-posix.c b/util/oslib-posix.c > index ad8001a4ad..236b3a88c1 100644 > --- a/util/oslib-posix.c > +++ b/util/oslib-posix.c > @@ -227,7 +227,7 @@ void *qemu_memalign(size_t alignment, size_t size) > void *qemu_anon_ram_alloc(size_t size, uint64_t *alignment, bool shared) > { > size_t align =3D QEMU_VMALLOC_ALIGN; > - void *ptr =3D qemu_ram_mmap(-1, size, align, shared, false); > + void *ptr =3D qemu_ram_mmap(-1, size, align, false, shared, false); > =20 > if (ptr =3D=3D MAP_FAILED) { > return NULL;