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:
for example IBM pSeries machines not all firmware/hypervisor
versions necessarily support PCI PIO access on all domains.
Add a property to make it possible to tweak the BAR type.
Signed-off-by: Michael S. Tsirkin <m...@redhat.com>
---
OK I added old_mmio (BTW: would be nice if ops were checked when
region is inited) and now things work in userspace.
However, when I add ioeventfd=on I get an assert:
qemu/kvm-all.c:747: kvm_mem_ioeventfd_add: Assertion `match_data &&
section->size == 4' failed.
How to reproduce:
1. apply patch
2. create virtio device with flags mmio=on,ioeventfd=on
hw/virtio-pci.c | 68 +++++++++++++++++++++++++++++++++++++++++++++++++++++-
hw/virtio-pci.h | 5 ++++
2 files changed, 71 insertions(+), 2 deletions(-)
diff --git a/hw/virtio-pci.c b/hw/virtio-pci.c
index 28498ec..b061000 100644
--- a/hw/virtio-pci.c
+++ b/hw/virtio-pci.c
@@ -510,8 +510,58 @@ const MemoryRegionPortio virtio_portio[] = {
PORTIO_END_OF_LIST()
};
+static void virtio_pci_config_mmio_writeb(void *opaque, target_phys_addr_t
addr, uint32_t val)
+{
+ VirtIOPCIProxy *proxy = opaque;
+ virtio_pci_config_writeb(opaque, addr & proxy->bar0_mask, val);
+}
+
+static void virtio_pci_config_mmio_writew(void *opaque, target_phys_addr_t
addr, uint32_t val)
+{
+ VirtIOPCIProxy *proxy = opaque;
+ virtio_pci_config_writew(opaque, addr & proxy->bar0_mask, val);
+}
+
+static void virtio_pci_config_mmio_writel(void *opaque, target_phys_addr_t
addr, uint32_t val)
+{
+ VirtIOPCIProxy *proxy = opaque;
+ virtio_pci_config_writel(opaque, addr & proxy->bar0_mask, val);
+}
+
+static uint32_t virtio_pci_config_mmio_readb(void *opaque, target_phys_addr_t
addr)
+{
+ VirtIOPCIProxy *proxy = opaque;
+ return virtio_pci_config_readb(opaque, addr & proxy->bar0_mask);
+}
+
+static uint32_t virtio_pci_config_mmio_readw(void *opaque, target_phys_addr_t
addr)
+{
+ VirtIOPCIProxy *proxy = opaque;
+ uint32_t val = virtio_pci_config_readw(opaque, addr & proxy->bar0_mask);
+ return val;
+}
+
+static uint32_t virtio_pci_config_mmio_readl(void *opaque, target_phys_addr_t
addr)
+{
+ VirtIOPCIProxy *proxy = opaque;
+ uint32_t val = virtio_pci_config_readl(opaque, addr & proxy->bar0_mask);
+ return val;
+}
+
static const MemoryRegionOps virtio_pci_config_ops = {
.old_portio = virtio_portio,
+ .old_mmio = {
+ .read = {
+ virtio_pci_config_mmio_readb,
+ virtio_pci_config_mmio_readw,
+ virtio_pci_config_mmio_readl,
+ },
+ .write = {
+ virtio_pci_config_mmio_writeb,
+ virtio_pci_config_mmio_writew,
+ virtio_pci_config_mmio_writel,
+ },
+ },
.endianness = DEVICE_LITTLE_ENDIAN,
};
@@ -655,6 +705,7 @@ void virtio_init_pci(VirtIOPCIProxy *proxy, VirtIODevice
*vdev)
{
uint8_t *config;
uint32_t size;
+ uint8_t bar0_type;
proxy->vdev = vdev;
@@ -682,10 +733,18 @@ void virtio_init_pci(VirtIOPCIProxy *proxy, VirtIODevice
*vdev)
if (size & (size-1))
size = 1 << qemu_fls(size);
+ proxy->bar0_mask = size - 1;
+
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 +882,7 @@ 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 +916,7 @@ 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 +949,7 @@ 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 +977,7 @@ 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 +1032,7 @@ 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..71ae5c9 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;
@@ -44,6 +48,7 @@ typedef struct {
VirtIOSCSIConf scsi;
bool ioeventfd_disabled;
bool ioeventfd_started;
+ unsigned bar0_mask;
} VirtIOPCIProxy;
void virtio_init_pci(VirtIOPCIProxy *proxy, VirtIODevice *vdev);
--
1.7.9.111.gf3fb0
