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virtio-pci: reduce modern_mem_bar size

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Currently each VQ Notification Virtio Capability is allocated
on a different page. The idea is to enable split drivers within
guests, however there are no known plans to do that.
The allocation will result in a 8MB BAR, more than various
guest firmwares pre-allocates for PCI Bridges hotplug process.

Reserve 4 bytes per VQ by default and add a new parameter
"page-per-vq" to be used with split drivers.

Signed-off-by: Marcel Apfelbaum <marcel@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Marcel Apfelbaum 2016-09-07 18:02:25 +03:00 • committed by Michael S. Tsirkin
parent 14c985cffa
commit d9997d89a4
3 changed files with 25 additions and 8 deletions
Download patch file Download diff file Expand all files Collapse all files

22
hw/virtio/virtio-pci.c
View file

@ -294,6 +294,12 @@ static void virtio_pci_ioeventfd_set_disabled(DeviceState *d, bool disabled)
#define QEMU_VIRTIO_PCI_QUEUE_MEM_MULT 0x1000
static inline int virtio_pci_queue_mem_mult(struct VirtIOPCIProxy *proxy)
{
return (proxy->flags & VIRTIO_PCI_FLAG_PAGE_PER_VQ) ?
QEMU_VIRTIO_PCI_QUEUE_MEM_MULT : 4;
}
static int virtio_pci_ioeventfd_assign(DeviceState *d, EventNotifier *notifier,
int n, bool assign)
{
@ -307,7 +313,7 @@ static int virtio_pci_ioeventfd_assign(DeviceState *d, EventNotifier *notifier,
MemoryRegion *modern_mr = &proxy->notify.mr;
MemoryRegion *modern_notify_mr = &proxy->notify_pio.mr;
MemoryRegion *legacy_mr = &proxy->bar;
hwaddr modern_addr = QEMU_VIRTIO_PCI_QUEUE_MEM_MULT *
hwaddr modern_addr = virtio_pci_queue_mem_mult(proxy) *
virtio_get_queue_index(vq);
hwaddr legacy_addr = VIRTIO_PCI_QUEUE_NOTIFY;
@ -1370,7 +1376,8 @@ static void virtio_pci_notify_write(void *opaque, hwaddr addr,
uint64_t val, unsigned size)
{
VirtIODevice *vdev = opaque;
unsigned queue = addr / QEMU_VIRTIO_PCI_QUEUE_MEM_MULT;
VirtIOPCIProxy *proxy = VIRTIO_PCI(DEVICE(vdev)->parent_bus->parent);
unsigned queue = addr / virtio_pci_queue_mem_mult(proxy);
if (queue < VIRTIO_QUEUE_MAX) {
virtio_queue_notify(vdev, queue);
@ -1609,7 +1616,7 @@ static void virtio_pci_device_plugged(DeviceState *d, Error **errp)
struct virtio_pci_notify_cap notify = {
.cap.cap_len = sizeof notify,
.notify_off_multiplier =
cpu_to_le32(QEMU_VIRTIO_PCI_QUEUE_MEM_MULT),
cpu_to_le32(virtio_pci_queue_mem_mult(proxy)),
};
struct virtio_pci_cfg_cap cfg = {
.cap.cap_len = sizeof cfg,
@ -1744,8 +1751,7 @@ static void virtio_pci_realize(PCIDevice *pci_dev, Error **errp)
proxy->device.type = VIRTIO_PCI_CAP_DEVICE_CFG;
proxy->notify.offset = 0x3000;
proxy->notify.size =
QEMU_VIRTIO_PCI_QUEUE_MEM_MULT * VIRTIO_QUEUE_MAX;
proxy->notify.size = virtio_pci_queue_mem_mult(proxy) * VIRTIO_QUEUE_MAX;
proxy->notify.type = VIRTIO_PCI_CAP_NOTIFY_CFG;
proxy->notify_pio.offset = 0x0;
@ -1754,8 +1760,8 @@ static void virtio_pci_realize(PCIDevice *pci_dev, Error **errp)
/* subclasses can enforce modern, so do this unconditionally */
memory_region_init(&proxy->modern_bar, OBJECT(proxy), "virtio-pci",
2 * QEMU_VIRTIO_PCI_QUEUE_MEM_MULT *
VIRTIO_QUEUE_MAX);
/* PCI BAR regions must be powers of 2 */
pow2ceil(proxy->notify.offset + proxy->notify.size));
memory_region_init_alias(&proxy->modern_cfg,
OBJECT(proxy),
@ -1833,6 +1839,8 @@ static Property virtio_pci_properties[] = {
VIRTIO_PCI_FLAG_MODERN_PIO_NOTIFY_BIT, false),
DEFINE_PROP_BIT("x-disable-pcie", VirtIOPCIProxy, flags,
VIRTIO_PCI_FLAG_DISABLE_PCIE_BIT, false),
DEFINE_PROP_BIT("page-per-vq", VirtIOPCIProxy, flags,
VIRTIO_PCI_FLAG_PAGE_PER_VQ_BIT, false),
DEFINE_PROP_END_OF_LIST(),
};