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[Qemu-devel] [PATCH RFC] virtio-pci: add MMIO property
From: |
Michael S. Tsirkin |
Subject: |
[Qemu-devel] [PATCH RFC] virtio-pci: add MMIO property |
Date: |
Mon, 19 Mar 2012 17:56:51 +0200 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
Currently virtio-pci is specified so that configuration of the device is
done through a PCI IO space (via BAR 0 of the virtual PCI device).
However, Linux guests happen to use ioread/iowrite/iomap primitives
for access, and these work uniformly across memory/io BARs.
While PCI IO accesses are faster than MMIO on x86 kvm,
MMIO might be helpful on other systems which don't
implement PIO or where PIO is slower than MMIO.
Add a property to make it possible to tweak the BAR type.
Signed-off-by: Michael S. Tsirkin <address@hidden>
This is harmless by default but causes segfaults in memory.c
when enabled. Thus an RFC until I figure out what's wrong.
---
hw/virtio-pci.c | 16 ++++++++++++++--
hw/virtio-pci.h | 4 ++++
2 files changed, 18 insertions(+), 2 deletions(-)
diff --git a/hw/virtio-pci.c b/hw/virtio-pci.c
index 28498ec..6f338d2 100644
--- a/hw/virtio-pci.c
+++ b/hw/virtio-pci.c
@@ -655,6 +655,7 @@ void virtio_init_pci(VirtIOPCIProxy *proxy, VirtIODevice
*vdev)
{
uint8_t *config;
uint32_t size;
+ uint8_t bar0_type;
proxy->vdev = vdev;
@@ -684,8 +685,14 @@ void virtio_init_pci(VirtIOPCIProxy *proxy, VirtIODevice
*vdev)
memory_region_init_io(&proxy->bar, &virtio_pci_config_ops, proxy,
"virtio-pci", size);
- pci_register_bar(&proxy->pci_dev, 0, PCI_BASE_ADDRESS_SPACE_IO,
- &proxy->bar);
+
+ if (proxy->flags & VIRTIO_PCI_FLAG_USE_MMIO) {
+ bar0_type = PCI_BASE_ADDRESS_SPACE_MEMORY;
+ } else {
+ bar0_type = PCI_BASE_ADDRESS_SPACE_IO;
+ }
+
+ pci_register_bar(&proxy->pci_dev, 0, bar0_type, &proxy->bar);
if (!kvm_has_many_ioeventfds()) {
proxy->flags &= ~VIRTIO_PCI_FLAG_USE_IOEVENTFD;
@@ -823,6 +830,7 @@ static Property virtio_blk_properties[] = {
DEFINE_PROP_BIT("ioeventfd", VirtIOPCIProxy, flags,
VIRTIO_PCI_FLAG_USE_IOEVENTFD_BIT, true),
DEFINE_PROP_UINT32("vectors", VirtIOPCIProxy, nvectors, 2),
DEFINE_VIRTIO_BLK_FEATURES(VirtIOPCIProxy, host_features),
+ DEFINE_PROP_BIT("mmio", VirtIOPCIProxy, flags,
VIRTIO_PCI_FLAG_USE_MMIO_BIT, false),
DEFINE_PROP_END_OF_LIST(),
};
@@ -856,6 +864,7 @@ static Property virtio_net_properties[] = {
DEFINE_PROP_UINT32("x-txtimer", VirtIOPCIProxy, net.txtimer,
TX_TIMER_INTERVAL),
DEFINE_PROP_INT32("x-txburst", VirtIOPCIProxy, net.txburst, TX_BURST),
DEFINE_PROP_STRING("tx", VirtIOPCIProxy, net.tx),
+ DEFINE_PROP_BIT("mmio", VirtIOPCIProxy, flags,
VIRTIO_PCI_FLAG_USE_MMIO_BIT, false),
DEFINE_PROP_END_OF_LIST(),
};
@@ -888,6 +897,7 @@ static Property virtio_serial_properties[] = {
DEFINE_PROP_HEX32("class", VirtIOPCIProxy, class_code, 0),
DEFINE_VIRTIO_COMMON_FEATURES(VirtIOPCIProxy, host_features),
DEFINE_PROP_UINT32("max_ports", VirtIOPCIProxy,
serial.max_virtserial_ports, 31),
+ DEFINE_PROP_BIT("mmio", VirtIOPCIProxy, flags,
VIRTIO_PCI_FLAG_USE_MMIO_BIT, false),
DEFINE_PROP_END_OF_LIST(),
};
@@ -915,6 +925,7 @@ static TypeInfo virtio_serial_info = {
static Property virtio_balloon_properties[] = {
DEFINE_VIRTIO_COMMON_FEATURES(VirtIOPCIProxy, host_features),
+ DEFINE_PROP_BIT("mmio", VirtIOPCIProxy, flags,
VIRTIO_PCI_FLAG_USE_MMIO_BIT, false),
DEFINE_PROP_END_OF_LIST(),
};
@@ -969,6 +980,7 @@ static int virtio_scsi_exit_pci(PCIDevice *pci_dev)
static Property virtio_scsi_properties[] = {
DEFINE_PROP_UINT32("vectors", VirtIOPCIProxy, nvectors, 2),
DEFINE_VIRTIO_SCSI_PROPERTIES(VirtIOPCIProxy, host_features, scsi),
+ DEFINE_PROP_BIT("mmio", VirtIOPCIProxy, flags,
VIRTIO_PCI_FLAG_USE_MMIO_BIT, false),
DEFINE_PROP_END_OF_LIST(),
};
diff --git a/hw/virtio-pci.h b/hw/virtio-pci.h
index e560428..e6a8861 100644
--- a/hw/virtio-pci.h
+++ b/hw/virtio-pci.h
@@ -24,6 +24,10 @@
#define VIRTIO_PCI_FLAG_USE_IOEVENTFD_BIT 1
#define VIRTIO_PCI_FLAG_USE_IOEVENTFD (1 <<
VIRTIO_PCI_FLAG_USE_IOEVENTFD_BIT)
+/* Some guests don't support port IO. Use MMIO instead. */
+#define VIRTIO_PCI_FLAG_USE_MMIO_BIT 2
+#define VIRTIO_PCI_FLAG_USE_MMIO (1 << VIRTIO_PCI_FLAG_USE_MMIO_BIT)
+
typedef struct {
PCIDevice pci_dev;
VirtIODevice *vdev;
--
1.7.9.111.gf3fb0
- [Qemu-devel] [PATCH RFC] virtio-pci: add MMIO property,
Michael S. Tsirkin <=
- Re: [Qemu-devel] [PATCH RFC] virtio-pci: add MMIO property, Avi Kivity, 2012/03/19
- Re: [Qemu-devel] [PATCH RFC] virtio-pci: add MMIO property, Anthony Liguori, 2012/03/19
- Re: [Qemu-devel] [PATCH RFC] virtio-pci: add MMIO property, Michael S. Tsirkin, 2012/03/19
- Re: [Qemu-devel] [PATCH RFC] virtio-pci: add MMIO property, Anthony Liguori, 2012/03/19
- Re: [Qemu-devel] [PATCH RFC] virtio-pci: add MMIO property, Michael S. Tsirkin, 2012/03/19
- Re: [Qemu-devel] [PATCH RFC] virtio-pci: add MMIO property, Michael S. Tsirkin, 2012/03/19
- Re: [Qemu-devel] [PATCH RFC] virtio-pci: add MMIO property, Anthony Liguori, 2012/03/19
- Re: [Qemu-devel] [PATCH RFC] virtio-pci: add MMIO property, Rusty Russell, 2012/03/19