From patchwork Fri Dec 17 12:01:51 2010 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stefan Hajnoczi X-Patchwork-Id: 75882 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [199.232.76.165]) by ozlabs.org (Postfix) with ESMTP id B3F8EB6F1E for ; Fri, 17 Dec 2010 23:29:40 +1100 (EST) Received: from localhost ([127.0.0.1]:33534 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1PTZM7-0006kA-Qy for incoming@patchwork.ozlabs.org; Fri, 17 Dec 2010 07:24:15 -0500 Received: from [140.186.70.92] (port=36408 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1PTZ0i-0005VW-AR for qemu-devel@nongnu.org; Fri, 17 Dec 2010 07:02:15 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1PTZ0e-0000rv-38 for qemu-devel@nongnu.org; Fri, 17 Dec 2010 07:02:08 -0500 Received: from mtagate7.uk.ibm.com ([194.196.100.167]:45721) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1PTZ0d-0000qj-RN for qemu-devel@nongnu.org; Fri, 17 Dec 2010 07:02:04 -0500 Received: from d06nrmr1507.portsmouth.uk.ibm.com (d06nrmr1507.portsmouth.uk.ibm.com [9.149.38.233]) by mtagate7.uk.ibm.com (8.13.1/8.13.1) with ESMTP id oBHC2277016750 for ; Fri, 17 Dec 2010 12:02:02 GMT Received: from d06av11.portsmouth.uk.ibm.com (d06av11.portsmouth.uk.ibm.com [9.149.37.252]) by d06nrmr1507.portsmouth.uk.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id oBHC24MD3358926 for ; Fri, 17 Dec 2010 12:02:04 GMT Received: from d06av11.portsmouth.uk.ibm.com (loopback [127.0.0.1]) by d06av11.portsmouth.uk.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id oBHC22Tj007482 for ; Fri, 17 Dec 2010 05:02:02 -0700 Received: from stefanha-thinkpad.manchester-maybrook.uk.ibm.com (dyn-9-174-219-29.manchester-maybrook.uk.ibm.com [9.174.219.29]) by d06av11.portsmouth.uk.ibm.com (8.14.4/8.13.1/NCO v10.0 AVin) with ESMTP id oBHC1x6S007319; Fri, 17 Dec 2010 05:02:01 -0700 From: Stefan Hajnoczi To: Date: Fri, 17 Dec 2010 12:01:51 +0000 Message-Id: <1292587312-24511-4-git-send-email-stefanha@linux.vnet.ibm.com> X-Mailer: git-send-email 1.7.2.3 In-Reply-To: <1292587312-24511-1-git-send-email-stefanha@linux.vnet.ibm.com> References: <1292587312-24511-1-git-send-email-stefanha@linux.vnet.ibm.com> X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.6, seldom 2.4 (older, 4) Cc: Stefan Hajnoczi , "Michael S. Tsirkin" Subject: [Qemu-devel] [PATCH v6 3/4] virtio-pci: Don't use ioeventfd on old kernels X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org There used to be a limit of 6 KVM io bus devices inside the kernel. On such a kernel, don't use ioeventfd for virtqueue host notification since the limit is reached too easily. This ensures that existing vhost-net setups (which always use ioeventfd) have ioeventfds available so they can continue to work. Signed-off-by: Stefan Hajnoczi --- hw/virtio-pci.c | 4 ++++ kvm-all.c | 49 +++++++++++++++++++++++++++++++++++++++++++++++++ kvm-stub.c | 5 +++++ kvm.h | 1 + 4 files changed, 59 insertions(+), 0 deletions(-) diff --git a/hw/virtio-pci.c b/hw/virtio-pci.c index 6b12248..b2181fc 100644 --- a/hw/virtio-pci.c +++ b/hw/virtio-pci.c @@ -690,6 +690,10 @@ static void virtio_init_pci(VirtIOPCIProxy *proxy, VirtIODevice *vdev, pci_register_bar(&proxy->pci_dev, 0, size, PCI_BASE_ADDRESS_SPACE_IO, virtio_map); + if (!kvm_has_many_ioeventfds()) { + proxy->flags &= ~VIRTIO_PCI_FLAG_USE_IOEVENTFD; + } + virtio_bind_device(vdev, &virtio_pci_bindings, proxy); proxy->host_features |= 0x1 << VIRTIO_F_NOTIFY_ON_EMPTY; proxy->host_features |= 0x1 << VIRTIO_F_BAD_FEATURE; diff --git a/kvm-all.c b/kvm-all.c index cae24bb..255b6fa 100644 --- a/kvm-all.c +++ b/kvm-all.c @@ -28,6 +28,11 @@ #include "kvm.h" #include "bswap.h" +/* This check must be after config-host.h is included */ +#ifdef CONFIG_EVENTFD +#include +#endif + /* KVM uses PAGE_SIZE in it's definition of COALESCED_MMIO_MAX */ #define PAGE_SIZE TARGET_PAGE_SIZE @@ -72,6 +77,7 @@ struct KVMState int irqchip_in_kernel; int pit_in_kernel; int xsave, xcrs; + int many_ioeventfds; }; static KVMState *kvm_state; @@ -441,6 +447,39 @@ int kvm_check_extension(KVMState *s, unsigned int extension) return ret; } +static int kvm_check_many_ioeventfds(void) +{ + /* Older kernels have a 6 device limit on the KVM io bus. Find out so we + * can avoid creating too many ioeventfds. + */ +#ifdef CONFIG_EVENTFD + int ioeventfds[7]; + int i, ret = 0; + for (i = 0; i < ARRAY_SIZE(ioeventfds); i++) { + ioeventfds[i] = eventfd(0, EFD_CLOEXEC); + if (ioeventfds[i] < 0) { + break; + } + ret = kvm_set_ioeventfd_pio_word(ioeventfds[i], 0, i, true); + if (ret < 0) { + close(ioeventfds[i]); + break; + } + } + + /* Decide whether many devices are supported or not */ + ret = i == ARRAY_SIZE(ioeventfds); + + while (i-- > 0) { + kvm_set_ioeventfd_pio_word(ioeventfds[i], 0, i, false); + close(ioeventfds[i]); + } + return ret; +#else + return 0; +#endif +} + static void kvm_set_phys_mem(target_phys_addr_t start_addr, ram_addr_t size, ram_addr_t phys_offset) @@ -717,6 +756,8 @@ int kvm_init(int smp_cpus) kvm_state = s; cpu_register_phys_memory_client(&kvm_cpu_phys_memory_client); + s->many_ioeventfds = kvm_check_many_ioeventfds(); + return 0; err: @@ -1046,6 +1087,14 @@ int kvm_has_xcrs(void) return kvm_state->xcrs; } +int kvm_has_many_ioeventfds(void) +{ + if (!kvm_enabled()) { + return 0; + } + return kvm_state->many_ioeventfds; +} + void kvm_setup_guest_memory(void *start, size_t size) { if (!kvm_has_sync_mmu()) { diff --git a/kvm-stub.c b/kvm-stub.c index 5384a4b..33d4476 100644 --- a/kvm-stub.c +++ b/kvm-stub.c @@ -99,6 +99,11 @@ int kvm_has_robust_singlestep(void) return 0; } +int kvm_has_many_ioeventfds(void) +{ + return 0; +} + void kvm_setup_guest_memory(void *start, size_t size) { } diff --git a/kvm.h b/kvm.h index 60a9b42..ce08d42 100644 --- a/kvm.h +++ b/kvm.h @@ -42,6 +42,7 @@ int kvm_has_robust_singlestep(void); int kvm_has_debugregs(void); int kvm_has_xsave(void); int kvm_has_xcrs(void); +int kvm_has_many_ioeventfds(void); #ifdef NEED_CPU_H int kvm_init_vcpu(CPUState *env);