From 3cb35556dc7d994f203d732fe952f95fcdb03c0a 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. Signed-off-by: Bandan Das Rebase notes (2.8.0): - removed return value for vfio_realize (commit 1a22aca) Merged patches (2.9.0): - 17eb774 vfio: Use error_setg when reporting max assigned device overshoot (cherry picked from commit 9fa3c9fc6dfcde76d80db1aa601b2d577f72ceec) --- hw/vfio/pci.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c index 31e1edf..f3f1ce6 100644 --- a/hw/vfio/pci.c +++ b/hw/vfio/pci.c @@ -34,6 +34,7 @@ #include "qapi/error.h" #define MSIX_CAP_LENGTH 12 +#define MAX_DEV_ASSIGN_CMDLINE 32 static void vfio_disable_interrupts(VFIOPCIDevice *vdev); static void vfio_mmap_set_enabled(VFIOPCIDevice *vdev, bool enabled); @@ -2639,7 +2640,19 @@ static void vfio_realize(PCIDevice *pdev, Error **errp) ssize_t len; struct stat st; int groupid; - int i, ret; + int ret, i = 0; + + QLIST_FOREACH(group, &vfio_group_list, next) { + QLIST_FOREACH(vbasedev_iter, &group->device_list, next) { + i++; + } + } + + if (i >= MAX_DEV_ASSIGN_CMDLINE) { + error_setg(errp, "Maximum supported vfio devices (%d) " + "already attached", MAX_DEV_ASSIGN_CMDLINE); + return; + } if (!vdev->vbasedev.sysfsdev) { if (!(~vdev->host.domain || ~vdev->host.bus || -- 1.8.3.1