qemu-kvm/0017-vfio-cap-number-of-devices-that-can-be-assigned.patch
Miroslav Rezanina a3dbefdd73 * Fri Aug 29 2025 Miroslav Rezanina <mrezanin@redhat.com> - 10.1.0-1
- Rebase to QEMU 10.1.0 [RHEL-105035]
- Resolves: RHEL-105035
  (Rebase qemu-kvm to QEMU 10.1.0)
2025-08-29 01:25:25 -04:00

141 lines
5.0 KiB
Diff

From 0f17fef61fc05f7617e47fcbc6a6c13efa5435d8 Mon Sep 17 00:00:00 2001
From: Bandan Das <bsd@redhat.com>
Date: Tue, 3 Dec 2013 20:05:13 +0100
Subject: vfio: cap number of devices that can be assigned
RH-Author: Bandan Das <bsd@redhat.com>
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 <alex.williamson@redhat.com>
RH-Acked-by: Marcelo Tosatti <mtosatti@redhat.com>
RH-Acked-by: Michael S. Tsirkin <mst@redhat.com>
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 <bsd@redhat.com>
Rebase changes (8.2.0):
- Update to upstream changes
Rebased notes (10.1.0)
- Update to upstream changes
- Introduced vfio_device_count()
---
hw/vfio/container.c | 14 ++++++++++++++
hw/vfio/pci.c | 21 +++++++++++++++++++++
hw/vfio/pci.h | 1 +
include/hw/vfio/vfio-device.h | 1 +
4 files changed, 37 insertions(+)
diff --git a/hw/vfio/container.c b/hw/vfio/container.c
index 3e13feaa74..b912b9396b 100644
--- a/hw/vfio/container.c
+++ b/hw/vfio/container.c
@@ -44,6 +44,20 @@ typedef QLIST_HEAD(VFIOGroupList, VFIOGroup) VFIOGroupList;
static VFIOGroupList vfio_group_list =
QLIST_HEAD_INITIALIZER(vfio_group_list);
+int vfio_device_count(void)
+{
+ int i = 0;
+ VFIOGroup *group;
+ VFIODevice *vbasedev_iter;
+
+ QLIST_FOREACH(group, &vfio_group_list, next) {
+ QLIST_FOREACH(vbasedev_iter, &group->device_list, next) {
+ i++;
+ }
+ }
+ return i;
+}
+
static int vfio_ram_block_discard_disable(VFIOContainer *container, bool state)
{
switch (container->iommu_type) {
diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
index 07257d0fa0..48da233cb2 100644
--- a/hw/vfio/pci.c
+++ b/hw/vfio/pci.c
@@ -52,6 +52,9 @@
/* Protected by BQL */
static KVMRouteChange vfio_route_change;
+/* 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);
static void vfio_msi_disable_common(VFIOPCIDevice *vdev);
@@ -3355,6 +3358,21 @@ static void vfio_pci_realize(PCIDevice *pdev, Error **errp)
char uuid[UUID_STR_LEN];
g_autofree char *name = NULL;
+ 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;
+ }
+
+ if (vfio_device_count() >= vdev->assigned_device_limit) {
+ error_setg(errp, "Maximum supported vfio devices (%d) "
+ "already attached", vdev->assigned_device_limit);
+ return;
+ }
+
if (vbasedev->fd < 0 && !vbasedev->sysfsdev) {
if (!(~vdev->host.domain || ~vdev->host.bus ||
~vdev->host.slot || ~vdev->host.function)) {
@@ -3687,6 +3705,9 @@ static const 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 810a842f4a..81555d8774 100644
--- a/hw/vfio/pci.h
+++ b/hw/vfio/pci.h
@@ -145,6 +145,7 @@ 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;
diff --git a/include/hw/vfio/vfio-device.h b/include/hw/vfio/vfio-device.h
index 6e4d5ccdac..9290774299 100644
--- a/include/hw/vfio/vfio-device.h
+++ b/include/hw/vfio/vfio-device.h
@@ -140,6 +140,7 @@ struct VFIODeviceOps {
#define strwriteerror(ret) \
(ret < 0 ? strerror(-ret) : "short write")
+int vfio_device_count(void);
void vfio_device_irq_disable(VFIODevice *vbasedev, int index);
void vfio_device_irq_unmask(VFIODevice *vbasedev, int index);
void vfio_device_irq_mask(VFIODevice *vbasedev, int index);
--
2.39.3