From patchwork Wed Jul 20 17:59:00 2011 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sasha Levin X-Patchwork-Id: 992832 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by demeter1.kernel.org (8.14.4/8.14.4) with ESMTP id p6KI0F7g016710 for ; Wed, 20 Jul 2011 18:00:16 GMT Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751877Ab1GTSAL (ORCPT ); Wed, 20 Jul 2011 14:00:11 -0400 Received: from mail-wy0-f174.google.com ([74.125.82.174]:47230 "EHLO mail-wy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751765Ab1GTSAK (ORCPT ); Wed, 20 Jul 2011 14:00:10 -0400 Received: by wyg8 with SMTP id 8so345468wyg.19 for ; Wed, 20 Jul 2011 11:00:09 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=from:to:cc:subject:date:message-id:x-mailer; bh=ZThip0FXfhjdUffz7m2tAxbvYyaovO/0Nhd9MWu9XhE=; b=WpRr3Ip0r9QIq/10eYiCwRGx3BDWIfHpaHKjmgYm7jSvdS9GJ+aVjhdREUgCoWX6o3 UpxjwwmoknblwjdLh04qG6LOxUVljYaL9uO/WEEJVB4moSPeudisHMQWYXHiYdZlxyeO WLmtT6jpzduw1a4DTu7ESXQDdlDpnxZRV1DNs= Received: by 10.227.147.67 with SMTP id k3mr4312682wbv.6.1311184809157; Wed, 20 Jul 2011 11:00:09 -0700 (PDT) Received: from localhost.localdomain (bzq-84-108-124-69.cablep.bezeqint.net [84.108.124.69]) by mx.google.com with ESMTPS id fo2sm379405wbb.65.2011.07.20.11.00.06 (version=TLSv1/SSLv3 cipher=OTHER); Wed, 20 Jul 2011 11:00:08 -0700 (PDT) From: Sasha Levin To: kvm@vger.kernel.org Cc: Sasha Levin , Avi Kivity , Marcelo Tosatti Subject: [PATCH v4] MMIO: Make coalesced mmio use a device per zone Date: Wed, 20 Jul 2011 20:59:00 +0300 Message-Id: <1311184740-14256-1-git-send-email-levinsasha928@gmail.com> X-Mailer: git-send-email 1.7.6 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org X-Greylist: IP, sender and recipient auto-whitelisted, not delayed by milter-greylist-4.2.6 (demeter1.kernel.org [140.211.167.41]); Wed, 20 Jul 2011 18:00:50 +0000 (UTC) This patch changes coalesced mmio to create one mmio device per zone instead of handling all zones in one device. Doing so enables us to take advantage of existing locking and prevents a race condition between coalesced mmio registration/unregistration and lookups. Cc: Avi Kivity Cc: Marcelo Tosatti Suggested-by: Avi Kivity Signed-off-by: Sasha Levin --- include/linux/kvm_host.h | 5 +- virt/kvm/coalesced_mmio.c | 118 ++++++++++++++++++--------------------------- virt/kvm/coalesced_mmio.h | 7 +-- 3 files changed, 53 insertions(+), 77 deletions(-) diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index eabb21a..ff4d406 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -63,7 +63,7 @@ extern struct kmem_cache *kvm_vcpu_cache; */ struct kvm_io_bus { int dev_count; -#define NR_IOBUS_DEVS 200 +#define NR_IOBUS_DEVS 300 struct kvm_io_device *devs[NR_IOBUS_DEVS]; }; @@ -256,8 +256,9 @@ struct kvm { struct kvm_arch arch; atomic_t users_count; #ifdef KVM_COALESCED_MMIO_PAGE_OFFSET - struct kvm_coalesced_mmio_dev *coalesced_mmio_dev; struct kvm_coalesced_mmio_ring *coalesced_mmio_ring; + spinlock_t ring_lock; + struct list_head coalesced_zones; #endif struct mutex irq_lock; diff --git a/virt/kvm/coalesced_mmio.c b/virt/kvm/coalesced_mmio.c index ae075dc..2316ec1 100644 --- a/virt/kvm/coalesced_mmio.c +++ b/virt/kvm/coalesced_mmio.c @@ -24,23 +24,13 @@ static inline struct kvm_coalesced_mmio_dev *to_mmio(struct kvm_io_device *dev) static int coalesced_mmio_in_range(struct kvm_coalesced_mmio_dev *dev, gpa_t addr, int len) { - struct kvm_coalesced_mmio_zone *zone; - int i; - - /* is it in a batchable area ? */ - - for (i = 0; i < dev->nb_zones; i++) { - zone = &dev->zone[i]; - - /* (addr,len) is fully included in - * (zone->addr, zone->size) - */ + /* is it in a batchable area ? + * (addr,len) is fully included in + * (zone->addr, zone->size) + */ - if (zone->addr <= addr && - addr + len <= zone->addr + zone->size) - return 1; - } - return 0; + return (dev->zone.addr <= addr && + addr + len <= dev->zone.addr + dev->zone.size); } static int coalesced_mmio_has_room(struct kvm_coalesced_mmio_dev *dev) @@ -73,10 +63,10 @@ static int coalesced_mmio_write(struct kvm_io_device *this, if (!coalesced_mmio_in_range(dev, addr, len)) return -EOPNOTSUPP; - spin_lock(&dev->lock); + spin_lock(&dev->kvm->ring_lock); if (!coalesced_mmio_has_room(dev)) { - spin_unlock(&dev->lock); + spin_unlock(&dev->kvm->ring_lock); return -EOPNOTSUPP; } @@ -87,7 +77,7 @@ static int coalesced_mmio_write(struct kvm_io_device *this, memcpy(ring->coalesced_mmio[ring->last].data, val, len); smp_wmb(); ring->last = (ring->last + 1) % KVM_COALESCED_MMIO_MAX; - spin_unlock(&dev->lock); + spin_unlock(&dev->kvm->ring_lock); return 0; } @@ -95,6 +85,8 @@ static void coalesced_mmio_destructor(struct kvm_io_device *this) { struct kvm_coalesced_mmio_dev *dev = to_mmio(this); + list_del(&dev->list); + kfree(dev); } @@ -105,7 +97,6 @@ static const struct kvm_io_device_ops coalesced_mmio_ops = { int kvm_coalesced_mmio_init(struct kvm *kvm) { - struct kvm_coalesced_mmio_dev *dev; struct page *page; int ret; @@ -113,31 +104,18 @@ int kvm_coalesced_mmio_init(struct kvm *kvm) page = alloc_page(GFP_KERNEL | __GFP_ZERO); if (!page) goto out_err; - kvm->coalesced_mmio_ring = page_address(page); - ret = -ENOMEM; - dev = kzalloc(sizeof(struct kvm_coalesced_mmio_dev), GFP_KERNEL); - if (!dev) - goto out_free_page; - spin_lock_init(&dev->lock); - kvm_iodevice_init(&dev->dev, &coalesced_mmio_ops); - dev->kvm = kvm; - kvm->coalesced_mmio_dev = dev; - - mutex_lock(&kvm->slots_lock); - ret = kvm_io_bus_register_dev(kvm, KVM_MMIO_BUS, &dev->dev); - mutex_unlock(&kvm->slots_lock); - if (ret < 0) - goto out_free_dev; + ret = 0; + kvm->coalesced_mmio_ring = page_address(page); - return ret; + /* + * We're using this spinlock to sync access to the coalesced ring. + * The list doesn't need it's own lock since device registration and + * unregistration should only happen when kvm->slots_lock is held. + */ + spin_lock_init(&kvm->ring_lock); + INIT_LIST_HEAD(&kvm->coalesced_zones); -out_free_dev: - kvm->coalesced_mmio_dev = NULL; - kfree(dev); -out_free_page: - kvm->coalesced_mmio_ring = NULL; - __free_page(page); out_err: return ret; } @@ -151,51 +129,49 @@ void kvm_coalesced_mmio_free(struct kvm *kvm) int kvm_vm_ioctl_register_coalesced_mmio(struct kvm *kvm, struct kvm_coalesced_mmio_zone *zone) { - struct kvm_coalesced_mmio_dev *dev = kvm->coalesced_mmio_dev; + int ret; + struct kvm_coalesced_mmio_dev *dev; - if (dev == NULL) - return -ENXIO; + dev = kzalloc(sizeof(struct kvm_coalesced_mmio_dev), GFP_KERNEL); + if (!dev) + return -ENOMEM; + + kvm_iodevice_init(&dev->dev, &coalesced_mmio_ops); + dev->kvm = kvm; + dev->zone = *zone; mutex_lock(&kvm->slots_lock); - if (dev->nb_zones >= KVM_COALESCED_MMIO_ZONE_MAX) { - mutex_unlock(&kvm->slots_lock); - return -ENOBUFS; - } + ret = kvm_io_bus_register_dev(kvm, KVM_MMIO_BUS, &dev->dev); + if (ret < 0) + goto out_free_dev; + list_add_tail(&dev->list, &kvm->coalesced_zones); + mutex_unlock(&kvm->slots_lock); - dev->zone[dev->nb_zones] = *zone; - dev->nb_zones++; + return ret; +out_free_dev: mutex_unlock(&kvm->slots_lock); + + kfree(dev); + + if (dev == NULL) + return -ENXIO; + return 0; } int kvm_vm_ioctl_unregister_coalesced_mmio(struct kvm *kvm, struct kvm_coalesced_mmio_zone *zone) { - int i; - struct kvm_coalesced_mmio_dev *dev = kvm->coalesced_mmio_dev; - struct kvm_coalesced_mmio_zone *z; - - if (dev == NULL) - return -ENXIO; + struct kvm_coalesced_mmio_dev *dev, *tmp; mutex_lock(&kvm->slots_lock); - i = dev->nb_zones; - while (i) { - z = &dev->zone[i - 1]; - - /* unregister all zones - * included in (zone->addr, zone->size) - */ - - if (zone->addr <= z->addr && - z->addr + z->size <= zone->addr + zone->size) { - dev->nb_zones--; - *z = dev->zone[dev->nb_zones]; + list_for_each_entry_safe(dev, tmp, &kvm->coalesced_zones, list) + if (coalesced_mmio_in_range(dev, zone->addr, zone->size)) { + kvm_io_bus_unregister_dev(kvm, KVM_MMIO_BUS, &dev->dev); + kvm_iodevice_destructor(&dev->dev); } - i--; - } mutex_unlock(&kvm->slots_lock); diff --git a/virt/kvm/coalesced_mmio.h b/virt/kvm/coalesced_mmio.h index 8a5959e..b280c20 100644 --- a/virt/kvm/coalesced_mmio.h +++ b/virt/kvm/coalesced_mmio.h @@ -12,14 +12,13 @@ #ifdef CONFIG_KVM_MMIO -#define KVM_COALESCED_MMIO_ZONE_MAX 100 +#include struct kvm_coalesced_mmio_dev { + struct list_head list; struct kvm_io_device dev; struct kvm *kvm; - spinlock_t lock; - int nb_zones; - struct kvm_coalesced_mmio_zone zone[KVM_COALESCED_MMIO_ZONE_MAX]; + struct kvm_coalesced_mmio_zone zone; }; int kvm_coalesced_mmio_init(struct kvm *kvm);