From patchwork Tue May 16 19:21:49 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stefano Stabellini X-Patchwork-Id: 9729581 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 4D1A260387 for ; Tue, 16 May 2017 19:23:07 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 3DB78289CB for ; Tue, 16 May 2017 19:23:07 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 32AF1289FB; Tue, 16 May 2017 19:23:07 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 1FDD7289CB for ; Tue, 16 May 2017 19:23:05 +0000 (UTC) Received: from localhost ([::1]:43621 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dAi3k-0003LL-C7 for patchwork-qemu-devel@patchwork.kernel.org; Tue, 16 May 2017 15:23:04 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:47287) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dAi2h-0003Kf-Gk for qemu-devel@nongnu.org; Tue, 16 May 2017 15:22:00 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dAi2e-0007nQ-9J for qemu-devel@nongnu.org; Tue, 16 May 2017 15:21:59 -0400 Received: from mail.kernel.org ([198.145.29.99]:50504) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1dAi2e-0007n8-0I for qemu-devel@nongnu.org; Tue, 16 May 2017 15:21:56 -0400 Received: from localhost.localdomain (unknown [99.165.194.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id AE628239CC; Tue, 16 May 2017 19:21:54 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org AE628239CC Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=sstabellini@kernel.org From: Stefano Stabellini To: peter.maydell@linaro.org, stefanha@gmail.com Date: Tue, 16 May 2017 12:21:49 -0700 Message-Id: <1494962512-4831-1-git-send-email-sstabellini@kernel.org> X-Mailer: git-send-email 1.9.1 In-Reply-To: References: X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 198.145.29.99 Subject: [Qemu-devel] [PULL 1/4] xen/mapcache: store dma information in revmapcache entries for debugging X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: anthony.perard@citrix.com, xen-devel@lists.xenproject.org, sstabellini@kernel.org, qemu-devel@nongnu.org, stefanha@redhat.com Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" X-Virus-Scanned: ClamAV using ClamSMTP The Xen mapcache is able to create long term mappings, they are called "locked" mappings. The third parameter of the xen_map_cache call specifies if a mapping is a "locked" mapping. >From the QEMU point of view there are two kinds of long term mappings: [a] device memory mappings, such as option roms and video memory [b] dma mappings, created by dma_memory_map & friends After certain operations, ballooning a VM in particular, Xen asks QEMU kindly to destroy all mappings. However, certainly [a] mappings are present and cannot be removed. That's not a problem as they are not affected by balloonning. The *real* problem is that if there are any mappings of type [b], any outstanding dma operations could fail. This is a known shortcoming. In other words, when Xen asks QEMU to destroy all mappings, it is an error if any [b] mappings exist. However today we have no way of distinguishing [a] from [b]. Because of that, we cannot even print a decent warning. This patch introduces a new "dma" bool field to MapCacheRev entires, to remember if a given mapping is for dma or is a long term device memory mapping. When xen_invalidate_map_cache is called, we print a warning if any [b] mappings exist. We ignore [a] mappings. Mappings created by qemu_map_ram_ptr are assumed to be [a], while mappings created by address_space_map->qemu_ram_ptr_length are assumed to be [b]. The goal of the patch is to make debugging and system understanding easier. Signed-off-by: Stefano Stabellini Acked-by: Paolo Bonzini Acked-by: Anthony PERARD --- exec.c | 8 ++++---- hw/i386/xen/xen-mapcache.c | 15 ++++++++++----- include/sysemu/xen-mapcache.h | 5 +++-- 3 files changed, 17 insertions(+), 11 deletions(-) diff --git a/exec.c b/exec.c index eac6085..85769e1 100644 --- a/exec.c +++ b/exec.c @@ -2084,10 +2084,10 @@ void *qemu_map_ram_ptr(RAMBlock *ram_block, ram_addr_t addr) * In that case just map until the end of the page. */ if (block->offset == 0) { - return xen_map_cache(addr, 0, 0); + return xen_map_cache(addr, 0, 0, false); } - block->host = xen_map_cache(block->offset, block->max_length, 1); + block->host = xen_map_cache(block->offset, block->max_length, 1, false); } return ramblock_ptr(block, addr); } @@ -2117,10 +2117,10 @@ static void *qemu_ram_ptr_length(RAMBlock *ram_block, ram_addr_t addr, * In that case just map the requested area. */ if (block->offset == 0) { - return xen_map_cache(addr, *size, 1); + return xen_map_cache(addr, *size, 1, true); } - block->host = xen_map_cache(block->offset, block->max_length, 1); + block->host = xen_map_cache(block->offset, block->max_length, 1, true); } return ramblock_ptr(block, addr); diff --git a/hw/i386/xen/xen-mapcache.c b/hw/i386/xen/xen-mapcache.c index 31debdf..e60156c 100644 --- a/hw/i386/xen/xen-mapcache.c +++ b/hw/i386/xen/xen-mapcache.c @@ -62,6 +62,7 @@ typedef struct MapCacheRev { hwaddr paddr_index; hwaddr size; QTAILQ_ENTRY(MapCacheRev) next; + bool dma; } MapCacheRev; typedef struct MapCache { @@ -202,7 +203,7 @@ static void xen_remap_bucket(MapCacheEntry *entry, } static uint8_t *xen_map_cache_unlocked(hwaddr phys_addr, hwaddr size, - uint8_t lock) + uint8_t lock, bool dma) { MapCacheEntry *entry, *pentry = NULL; hwaddr address_index; @@ -289,6 +290,7 @@ tryagain: if (lock) { MapCacheRev *reventry = g_malloc0(sizeof(MapCacheRev)); entry->lock++; + reventry->dma = dma; reventry->vaddr_req = mapcache->last_entry->vaddr_base + address_offset; reventry->paddr_index = mapcache->last_entry->paddr_index; reventry->size = entry->size; @@ -300,12 +302,12 @@ tryagain: } uint8_t *xen_map_cache(hwaddr phys_addr, hwaddr size, - uint8_t lock) + uint8_t lock, bool dma) { uint8_t *p; mapcache_lock(); - p = xen_map_cache_unlocked(phys_addr, size, lock); + p = xen_map_cache_unlocked(phys_addr, size, lock, dma); mapcache_unlock(); return p; } @@ -426,8 +428,11 @@ void xen_invalidate_map_cache(void) mapcache_lock(); QTAILQ_FOREACH(reventry, &mapcache->locked_entries, next) { - DPRINTF("There should be no locked mappings at this time, " - "but "TARGET_FMT_plx" -> %p is present\n", + if (!reventry->dma) { + continue; + } + fprintf(stderr, "Locked DMA mapping while invalidating mapcache!" + " "TARGET_FMT_plx" -> %p is present\n", reventry->paddr_index, reventry->vaddr_req); } diff --git a/include/sysemu/xen-mapcache.h b/include/sysemu/xen-mapcache.h index b8c93b9..01daaad 100644 --- a/include/sysemu/xen-mapcache.h +++ b/include/sysemu/xen-mapcache.h @@ -17,7 +17,7 @@ typedef hwaddr (*phys_offset_to_gaddr_t)(hwaddr start_addr, void xen_map_cache_init(phys_offset_to_gaddr_t f, void *opaque); uint8_t *xen_map_cache(hwaddr phys_addr, hwaddr size, - uint8_t lock); + uint8_t lock, bool dma); ram_addr_t xen_ram_addr_from_mapcache(void *ptr); void xen_invalidate_map_cache_entry(uint8_t *buffer); void xen_invalidate_map_cache(void); @@ -31,7 +31,8 @@ static inline void xen_map_cache_init(phys_offset_to_gaddr_t f, static inline uint8_t *xen_map_cache(hwaddr phys_addr, hwaddr size, - uint8_t lock) + uint8_t lock, + bool dma) { abort(); }