From 4110ee428550f672ee1a1a73a634d5392bf9c55f Mon Sep 17 00:00:00 2001 Message-Id: <4110ee428550f672ee1a1a73a634d5392bf9c55f.1387382496.git.minovotn@redhat.com> In-Reply-To: References: From: Bandan Das Date: Tue, 3 Dec 2013 20:05:13 +0100 Subject: [PATCH 44/46] 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 --- hw/misc/vfio.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) Signed-off-by: Michal Novotny --- hw/misc/vfio.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff --git a/hw/misc/vfio.c b/hw/misc/vfio.c index 250f96f..bd30130 100644 --- a/hw/misc/vfio.c +++ b/hw/misc/vfio.c @@ -201,6 +201,7 @@ typedef struct VFIOGroup { } VFIOGroup; #define MSIX_CAP_LENGTH 12 +#define MAX_DEV_ASSIGN_CMDLINE 32 static QLIST_HEAD(, VFIOContainer) container_list = QLIST_HEAD_INITIALIZER(container_list); @@ -3557,7 +3558,19 @@ static int vfio_initfn(PCIDevice *pdev) ssize_t len; struct stat st; int groupid; - int ret; + int ret, i = 0; + + QLIST_FOREACH(group, &group_list, next) { + QLIST_FOREACH(pvdev, &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), -- 1.7.11.7