From 55dcef9d806aa530f10e3ca42eb24d52f850d674 Mon Sep 17 00:00:00 2001 From: Bandan Das Date: Tue, 3 Dec 2013 20:05:13 +0100 Subject: vfio: cap number of devices that can be assigned RH-Author: Bandan Das Message-id: <1386101113-31560-3-git-send-email-bsd@redhat.com> Patchwork-id: 55984 O-Subject: [PATCH RHEL7 qemu-kvm v2 2/2] vfio: cap number of devices that can be assigned Bugzilla: 678368 RH-Acked-by: Alex Williamson RH-Acked-by: Marcelo Tosatti RH-Acked-by: Michael S. Tsirkin Go through all groups to get count of total number of devices active to enforce limit Reasoning from Alex for the limit(32) - Assuming 3 slots per device, with 125 slots (number of memory slots for RHEL 7), we can support almost 40 devices and still have few slots left for other uses. Stepping down a bit, the number 32 arbitrarily matches the number of slots on a PCI bus and is also a nice power of two. Count of slots increased to 509 later so we could increase limit to 64 as some usecases require more than 32 devices. Signed-off-by: Bandan Das --- hw/vfio/pci.c | 29 ++++++++++++++++++++++++++++- hw/vfio/pci.h | 1 + 2 files changed, 29 insertions(+), 1 deletion(-) diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c index 7b45353ce2..eb725a3aee 100644 --- a/hw/vfio/pci.c +++ b/hw/vfio/pci.c @@ -45,6 +45,9 @@ #define TYPE_VFIO_PCI_NOHOTPLUG "vfio-pci-nohotplug" +/* RHEL only: Set once for the first assigned dev */ +static uint16_t device_limit; + static void vfio_disable_interrupts(VFIOPCIDevice *vdev); static void vfio_mmap_set_enabled(VFIOPCIDevice *vdev, bool enabled); @@ -2807,9 +2810,30 @@ static void vfio_realize(PCIDevice *pdev, Error **errp) ssize_t len; struct stat st; int groupid; - int i, ret; + int ret, i = 0; bool is_mdev; + if (device_limit && device_limit != vdev->assigned_device_limit) { + error_setg(errp, "Assigned device limit has been redefined. " + "Old:%d, New:%d", + device_limit, vdev->assigned_device_limit); + return; + } else { + device_limit = vdev->assigned_device_limit; + } + + QLIST_FOREACH(group, &vfio_group_list, next) { + QLIST_FOREACH(vbasedev_iter, &group->device_list, next) { + i++; + } + } + + if (i >= vdev->assigned_device_limit) { + error_setg(errp, "Maximum supported vfio devices (%d) " + "already attached", vdev->assigned_device_limit); + return; + } + if (!vdev->vbasedev.sysfsdev) { if (!(~vdev->host.domain || ~vdev->host.bus || ~vdev->host.slot || ~vdev->host.function)) { @@ -3246,6 +3270,9 @@ static Property vfio_pci_dev_properties[] = { DEFINE_PROP_BOOL("x-no-kvm-msix", VFIOPCIDevice, no_kvm_msix, false), DEFINE_PROP_BOOL("x-no-geforce-quirks", VFIOPCIDevice, no_geforce_quirks, false), + /* RHEL only */ + DEFINE_PROP_UINT16("x-assigned-device-limit", VFIOPCIDevice, + assigned_device_limit, 64), DEFINE_PROP_BOOL("x-no-kvm-ioeventfd", VFIOPCIDevice, no_kvm_ioeventfd, false), DEFINE_PROP_BOOL("x-no-vfio-ioeventfd", VFIOPCIDevice, no_vfio_ioeventfd, diff --git a/hw/vfio/pci.h b/hw/vfio/pci.h index 64777516d1..e0fe6ca97e 100644 --- a/hw/vfio/pci.h +++ b/hw/vfio/pci.h @@ -139,6 +139,7 @@ struct VFIOPCIDevice { EventNotifier err_notifier; EventNotifier req_notifier; int (*resetfn)(struct VFIOPCIDevice *); + uint16_t assigned_device_limit; uint32_t vendor_id; uint32_t device_id; uint32_t sub_vendor_id; -- 2.27.0