From patchwork Wed Jan 2 15:15:41 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stefan Hajnoczi X-Patchwork-Id: 209057 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id 0A8B92C0086 for ; Thu, 3 Jan 2013 02:16:51 +1100 (EST) Received: from localhost ([::1]:41957 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TqQ3k-0000Pb-S7 for incoming@patchwork.ozlabs.org; Wed, 02 Jan 2013 10:16:48 -0500 Received: from eggs.gnu.org ([208.118.235.92]:42450) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TqQ3H-0008V3-Mi for qemu-devel@nongnu.org; Wed, 02 Jan 2013 10:16:26 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1TqQ3B-0005Zf-Tc for qemu-devel@nongnu.org; Wed, 02 Jan 2013 10:16:19 -0500 Received: from mx1.redhat.com ([209.132.183.28]:26712) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TqQ3B-0005ZX-ML for qemu-devel@nongnu.org; Wed, 02 Jan 2013 10:16:13 -0500 Received: from int-mx11.intmail.prod.int.phx2.redhat.com (int-mx11.intmail.prod.int.phx2.redhat.com [10.5.11.24]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id r02FGDEm031925 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Wed, 2 Jan 2013 10:16:13 -0500 Received: from localhost (ovpn-112-16.ams2.redhat.com [10.36.112.16]) by int-mx11.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id r02FGB9K032109; Wed, 2 Jan 2013 10:16:12 -0500 From: Stefan Hajnoczi To: Date: Wed, 2 Jan 2013 16:15:41 +0100 Message-Id: <1357139756-11951-4-git-send-email-stefanha@redhat.com> In-Reply-To: <1357139756-11951-1-git-send-email-stefanha@redhat.com> References: <1357139756-11951-1-git-send-email-stefanha@redhat.com> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.24 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x X-Received-From: 209.132.183.28 Cc: Anthony Liguori , Stefan Hajnoczi Subject: [Qemu-devel] [PATCH 03/18] dataplane: add host memory mapping code X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org The data plane thread needs to map guest physical addresses to host pointers. Normally this is done with cpu_physical_memory_map() but the function assumes the global mutex is held. The data plane thread does not touch the global mutex and therefore needs a thread-safe memory mapping mechanism. Hostmem registers a MemoryListener similar to how vhost collects and pushes memory region information into the kernel. There is a fine-grained lock on the regions list which is held during lookup and when installing a new regions list. When the physical memory map changes the MemoryListener callbacks are invoked. They build up a new list of memory regions which is finally installed when the list has been completed. Signed-off-by: Stefan Hajnoczi --- hw/Makefile.objs | 2 +- hw/dataplane/Makefile.objs | 3 + hw/dataplane/hostmem.c | 176 +++++++++++++++++++++++++++++++++++++++++++++ hw/dataplane/hostmem.h | 57 +++++++++++++++ 4 files changed, 237 insertions(+), 1 deletion(-) create mode 100644 hw/dataplane/Makefile.objs create mode 100644 hw/dataplane/hostmem.c create mode 100644 hw/dataplane/hostmem.h diff --git a/hw/Makefile.objs b/hw/Makefile.objs index d75f2f0..5ac4913 100644 --- a/hw/Makefile.objs +++ b/hw/Makefile.objs @@ -1,4 +1,4 @@ -common-obj-y = usb/ ide/ pci/ +common-obj-y = usb/ ide/ pci/ dataplane/ common-obj-y += loader.o common-obj-$(CONFIG_VIRTIO) += virtio-console.o common-obj-$(CONFIG_VIRTIO) += virtio-rng.o diff --git a/hw/dataplane/Makefile.objs b/hw/dataplane/Makefile.objs new file mode 100644 index 0000000..8c8dea1 --- /dev/null +++ b/hw/dataplane/Makefile.objs @@ -0,0 +1,3 @@ +ifeq ($(CONFIG_VIRTIO), y) +common-obj-$(CONFIG_VIRTIO_BLK_DATA_PLANE) += hostmem.o +endif diff --git a/hw/dataplane/hostmem.c b/hw/dataplane/hostmem.c new file mode 100644 index 0000000..380537e --- /dev/null +++ b/hw/dataplane/hostmem.c @@ -0,0 +1,176 @@ +/* + * Thread-safe guest to host memory mapping + * + * Copyright 2012 Red Hat, Inc. and/or its affiliates + * + * Authors: + * Stefan Hajnoczi + * + * This work is licensed under the terms of the GNU GPL, version 2 or later. + * See the COPYING file in the top-level directory. + * + */ + +#include "exec/address-spaces.h" +#include "hostmem.h" + +static int hostmem_lookup_cmp(const void *phys_, const void *region_) +{ + hwaddr phys = *(const hwaddr *)phys_; + const HostMemRegion *region = region_; + + if (phys < region->guest_addr) { + return -1; + } else if (phys >= region->guest_addr + region->size) { + return 1; + } else { + return 0; + } +} + +/** + * Map guest physical address to host pointer + */ +void *hostmem_lookup(HostMem *hostmem, hwaddr phys, hwaddr len, bool is_write) +{ + HostMemRegion *region; + void *host_addr = NULL; + hwaddr offset_within_region; + + qemu_mutex_lock(&hostmem->current_regions_lock); + region = bsearch(&phys, hostmem->current_regions, + hostmem->num_current_regions, + sizeof(hostmem->current_regions[0]), + hostmem_lookup_cmp); + if (!region) { + goto out; + } + if (is_write && region->readonly) { + goto out; + } + offset_within_region = phys - region->guest_addr; + if (len <= region->size - offset_within_region) { + host_addr = region->host_addr + offset_within_region; + } +out: + qemu_mutex_unlock(&hostmem->current_regions_lock); + + return host_addr; +} + +/** + * Install new regions list + */ +static void hostmem_listener_commit(MemoryListener *listener) +{ + HostMem *hostmem = container_of(listener, HostMem, listener); + + qemu_mutex_lock(&hostmem->current_regions_lock); + g_free(hostmem->current_regions); + hostmem->current_regions = hostmem->new_regions; + hostmem->num_current_regions = hostmem->num_new_regions; + qemu_mutex_unlock(&hostmem->current_regions_lock); + + /* Reset new regions list */ + hostmem->new_regions = NULL; + hostmem->num_new_regions = 0; +} + +/** + * Add a MemoryRegionSection to the new regions list + */ +static void hostmem_append_new_region(HostMem *hostmem, + MemoryRegionSection *section) +{ + void *ram_ptr = memory_region_get_ram_ptr(section->mr); + size_t num = hostmem->num_new_regions; + size_t new_size = (num + 1) * sizeof(hostmem->new_regions[0]); + + hostmem->new_regions = g_realloc(hostmem->new_regions, new_size); + hostmem->new_regions[num] = (HostMemRegion){ + .host_addr = ram_ptr + section->offset_within_region, + .guest_addr = section->offset_within_address_space, + .size = section->size, + .readonly = section->readonly, + }; + hostmem->num_new_regions++; +} + +static void hostmem_listener_append_region(MemoryListener *listener, + MemoryRegionSection *section) +{ + HostMem *hostmem = container_of(listener, HostMem, listener); + + /* Ignore non-RAM regions, we may not be able to map them */ + if (!memory_region_is_ram(section->mr)) { + return; + } + + /* Ignore regions with dirty logging, we cannot mark them dirty */ + if (memory_region_is_logging(section->mr)) { + return; + } + + hostmem_append_new_region(hostmem, section); +} + +/* We don't implement most MemoryListener callbacks, use these nop stubs */ +static void hostmem_listener_dummy(MemoryListener *listener) +{ +} + +static void hostmem_listener_section_dummy(MemoryListener *listener, + MemoryRegionSection *section) +{ +} + +static void hostmem_listener_eventfd_dummy(MemoryListener *listener, + MemoryRegionSection *section, + bool match_data, uint64_t data, + EventNotifier *e) +{ +} + +static void hostmem_listener_coalesced_mmio_dummy(MemoryListener *listener, + MemoryRegionSection *section, + hwaddr addr, hwaddr len) +{ +} + +void hostmem_init(HostMem *hostmem) +{ + memset(hostmem, 0, sizeof(*hostmem)); + + qemu_mutex_init(&hostmem->current_regions_lock); + + hostmem->listener = (MemoryListener){ + .begin = hostmem_listener_dummy, + .commit = hostmem_listener_commit, + .region_add = hostmem_listener_append_region, + .region_del = hostmem_listener_section_dummy, + .region_nop = hostmem_listener_append_region, + .log_start = hostmem_listener_section_dummy, + .log_stop = hostmem_listener_section_dummy, + .log_sync = hostmem_listener_section_dummy, + .log_global_start = hostmem_listener_dummy, + .log_global_stop = hostmem_listener_dummy, + .eventfd_add = hostmem_listener_eventfd_dummy, + .eventfd_del = hostmem_listener_eventfd_dummy, + .coalesced_mmio_add = hostmem_listener_coalesced_mmio_dummy, + .coalesced_mmio_del = hostmem_listener_coalesced_mmio_dummy, + .priority = 10, + }; + + memory_listener_register(&hostmem->listener, &address_space_memory); + if (hostmem->num_new_regions > 0) { + hostmem_listener_commit(&hostmem->listener); + } +} + +void hostmem_finalize(HostMem *hostmem) +{ + memory_listener_unregister(&hostmem->listener); + g_free(hostmem->new_regions); + g_free(hostmem->current_regions); + qemu_mutex_destroy(&hostmem->current_regions_lock); +} diff --git a/hw/dataplane/hostmem.h b/hw/dataplane/hostmem.h new file mode 100644 index 0000000..b2cf093 --- /dev/null +++ b/hw/dataplane/hostmem.h @@ -0,0 +1,57 @@ +/* + * Thread-safe guest to host memory mapping + * + * Copyright 2012 Red Hat, Inc. and/or its affiliates + * + * Authors: + * Stefan Hajnoczi + * + * This work is licensed under the terms of the GNU GPL, version 2 or later. + * See the COPYING file in the top-level directory. + * + */ + +#ifndef HOSTMEM_H +#define HOSTMEM_H + +#include "exec/memory.h" +#include "qemu/thread.h" + +typedef struct { + void *host_addr; + hwaddr guest_addr; + uint64_t size; + bool readonly; +} HostMemRegion; + +typedef struct { + /* The listener is invoked when regions change and a new list of regions is + * built up completely before they are installed. + */ + MemoryListener listener; + HostMemRegion *new_regions; + size_t num_new_regions; + + /* Current regions are accessed from multiple threads either to lookup + * addresses or to install a new list of regions. The lock protects the + * pointer and the regions. + */ + QemuMutex current_regions_lock; + HostMemRegion *current_regions; + size_t num_current_regions; +} HostMem; + +void hostmem_init(HostMem *hostmem); +void hostmem_finalize(HostMem *hostmem); + +/** + * Map a guest physical address to a pointer + * + * Note that there is map/unmap mechanism here. The caller must ensure that + * mapped memory is no longer used across events like hot memory unplug. This + * can be done with other mechanisms like bdrv_drain_all() that quiesce + * in-flight I/O. + */ +void *hostmem_lookup(HostMem *hostmem, hwaddr phys, hwaddr len, bool is_write); + +#endif /* HOSTMEM_H */