From f5252bbf663079c7500bb6c16fa1a85db854a8d3 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 diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c index 6b80539..62fcb3d 100644 --- a/hw/vfio/pci.c +++ b/hw/vfio/pci.c @@ -193,6 +193,7 @@ static const VFIORomBlacklistEntry romblacklist[] = { }; #define MSIX_CAP_LENGTH 12 +#define MAX_DEV_ASSIGN_CMDLINE 32 static void vfio_disable_interrupts(VFIOPCIDevice *vdev); static uint32_t vfio_pci_read_config(PCIDevice *pdev, uint32_t addr, int len); @@ -3328,7 +3329,19 @@ static int vfio_initfn(PCIDevice *pdev) ssize_t len; struct stat st; int groupid; - int 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_report("vfio: Maximum supported vfio devices (%d) " + "already attached\n", MAX_DEV_ASSIGN_CMDLINE); + return -1; + } /* Check that the host device exists */ snprintf(path, sizeof(path),