From patchwork Wed Feb 12 13:42:50 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Hildenbrand X-Patchwork-Id: 11378615 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id C5C61138D for ; Wed, 12 Feb 2020 13:55:49 +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 9C72B2082F for ; Wed, 12 Feb 2020 13:55:49 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="Dm3c9poY" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9C72B2082F 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+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Received: from localhost ([::1]:38266 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1j1sUW-0003Fu-RL for patchwork-qemu-devel@patchwork.kernel.org; Wed, 12 Feb 2020 08:55:48 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:39480) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1j1sJH-0007tV-5N for qemu-devel@nongnu.org; Wed, 12 Feb 2020 08:44:12 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1j1sJF-0004bl-Pu for qemu-devel@nongnu.org; Wed, 12 Feb 2020 08:44:11 -0500 Received: from us-smtp-2.mimecast.com ([207.211.31.81]:33943 helo=us-smtp-delivery-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1j1sJF-0004bT-M8 for qemu-devel@nongnu.org; Wed, 12 Feb 2020 08:44:09 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1581515049; 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=LnJzdyGqoAQKx+1rnNUMeCg39x2uBiI+oIICFGxMjgU=; b=Dm3c9poYRwF6xEmz2Z4uuV5UnsEfGKuRiuqZcrAks4NMNDE06VC+yAlf8WbFnaoJgDoCF5 0mdrksPGrOoMUf6U4OesGW1v4t3RhyfDQMkdDxtfgEgA1tAtFLlCMsNRQGmdFZTfEJkhhx mglIDrpxQePDIm/pEgLln01rGtvyNH0= 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-151-yX8BHRaIOYup158mDf75Yg-1; Wed, 12 Feb 2020 08:44:06 -0500 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 50651190D340; Wed, 12 Feb 2020 13:44:04 +0000 (UTC) Received: from t480s.redhat.com (ovpn-117-92.ams2.redhat.com [10.36.117.92]) by smtp.corp.redhat.com (Postfix) with ESMTP id 7552F1001281; Wed, 12 Feb 2020 13:43:54 +0000 (UTC) From: David Hildenbrand To: qemu-devel@nongnu.org Subject: [PATCH v2 fixed 12/16] util/mmap-alloc: Implement resizable mmaps Date: Wed, 12 Feb 2020 14:42:50 +0100 Message-Id: <20200212134254.11073-13-david@redhat.com> In-Reply-To: <20200212134254.11073-1-david@redhat.com> References: <20200212134254.11073-1-david@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-MC-Unique: yX8BHRaIOYup158mDf75Yg-1 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 207.211.31.81 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: Igor Kotrasinski , Eduardo Habkost , "Michael S . Tsirkin" , David Hildenbrand , Richard Henderson , "Dr . David Alan Gilbert" , Greg Kurz , Murilo Opsfelder Araujo , Igor Mammedov , Paolo Bonzini , Richard Henderson Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" Implement resizable mmaps. For now, the actual resizing is not wired up. Introduce qemu_ram_mmap_resizable() and qemu_ram_mmap_resize(). Make qemu_ram_mmap() a wrapper of qemu_ram_mmap_resizable(). Cc: Richard Henderson Cc: Igor Kotrasinski Cc: Murilo Opsfelder Araujo Cc: "Michael S. Tsirkin" Cc: Greg Kurz Cc: Eduardo Habkost Cc: "Dr. David Alan Gilbert" Cc: Igor Mammedov Signed-off-by: David Hildenbrand --- include/qemu/mmap-alloc.h | 21 ++++++++++++-------- util/mmap-alloc.c | 42 ++++++++++++++++++++++++++++----------- 2 files changed, 43 insertions(+), 20 deletions(-) diff --git a/include/qemu/mmap-alloc.h b/include/qemu/mmap-alloc.h index e786266b92..3a219721e3 100644 --- a/include/qemu/mmap-alloc.h +++ b/include/qemu/mmap-alloc.h @@ -7,11 +7,13 @@ size_t qemu_fd_getpagesize(int fd); size_t qemu_mempath_getpagesize(const char *mem_path); /** - * qemu_ram_mmap: mmap the specified file or device. + * qemu_ram_mmap_resizable: reserve a memory region of @max_size to mmap the + * specified file or device and mmap @size of it. * * Parameters: * @fd: the file or the device to mmap * @size: the number of bytes to be mmaped + * @max_size: the number of bytes to be reserved * @align: if not zero, specify the alignment of the starting mapping address; * otherwise, the alignment in use will be determined by QEMU. * @shared: map has RAM_SHARED flag. @@ -21,12 +23,15 @@ size_t qemu_mempath_getpagesize(const char *mem_path); * On success, return a pointer to the mapped area. * On failure, return MAP_FAILED. */ -void *qemu_ram_mmap(int fd, - size_t size, - size_t align, - bool shared, - bool is_pmem); - -void qemu_ram_munmap(int fd, void *ptr, size_t size); +void *qemu_ram_mmap_resizable(int fd, size_t size, size_t max_size, + size_t align, bool shared, bool is_pmem); +bool qemu_ram_mmap_resize(void *ptr, int fd, size_t old_size, size_t new_size, + bool shared, bool is_pmem); +static inline void *qemu_ram_mmap(int fd, size_t size, size_t align, + bool shared, bool is_pmem) +{ + return qemu_ram_mmap_resizable(fd, size, size, align, shared, is_pmem); +} +void qemu_ram_munmap(int fd, void *ptr, size_t max_size); #endif diff --git a/util/mmap-alloc.c b/util/mmap-alloc.c index fb7ef588fe..164b88a088 100644 --- a/util/mmap-alloc.c +++ b/util/mmap-alloc.c @@ -173,23 +173,22 @@ static inline size_t mmap_pagesize(int fd) #endif } -void *qemu_ram_mmap(int fd, - size_t size, - size_t align, - bool shared, - bool is_pmem) +void *qemu_ram_mmap_resizable(int fd, size_t size, size_t max_size, + size_t align, bool shared, bool is_pmem) { const size_t pagesize = mmap_pagesize(fd); size_t offset, total; void *ptr, *guardptr; g_assert(QEMU_IS_ALIGNED(size, pagesize)); + g_assert(QEMU_IS_ALIGNED(max_size, pagesize)); /* * Note: this always allocates at least one extra page of virtual address - * space, even if size is already aligned. + * space, even if the size is already aligned. We will reserve an area of + * at least max_size, but only populate the requested part of it. */ - total = size + align; + total = max_size + align; guardptr = mmap_reserve(0, total, fd); if (guardptr == MAP_FAILED) { @@ -217,21 +216,40 @@ void *qemu_ram_mmap(int fd, * a guard page guarding against potential buffer overflows. */ total -= offset; - if (total > size + pagesize) { - munmap(ptr + size + pagesize, total - size - pagesize); + if (total > max_size + pagesize) { + munmap(ptr + max_size + pagesize, total - max_size - pagesize); } return ptr; } -void qemu_ram_munmap(int fd, void *ptr, size_t size) +bool qemu_ram_mmap_resize(void *ptr, int fd, size_t old_size, size_t new_size, + bool shared, bool is_pmem) { const size_t pagesize = mmap_pagesize(fd); - g_assert(QEMU_IS_ALIGNED(size, pagesize)); + g_assert(QEMU_IS_ALIGNED(old_size, pagesize)); + g_assert(QEMU_IS_ALIGNED(new_size, pagesize)); + + if (old_size < new_size) { + /* populate the missing piece into the reserved area */ + ptr = mmap_populate(ptr + old_size, new_size - old_size, fd, old_size, + shared, is_pmem); + } else if (old_size > new_size) { + /* discard this piece, marking it reserved */ + ptr = mmap_reserve(ptr + new_size, old_size - new_size, fd); + } + return ptr != MAP_FAILED; +} + +void qemu_ram_munmap(int fd, void *ptr, size_t max_size) +{ + const size_t pagesize = mmap_pagesize(fd); + + g_assert(QEMU_IS_ALIGNED(max_size, pagesize)); if (ptr) { /* Unmap both the RAM block and the guard page */ - munmap(ptr, size + pagesize); + munmap(ptr, max_size + pagesize); } }