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 <mst@xxxxxxxxxx> 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 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html