Implement the ioeventfd_assign_begin() and ioeventfd_assign_commit() handlers of VirtioBusClass. Basically track that a transaction was already requested by the device and use this information to prevent the memory code to generate a transaction for each individual eventfd.
Devices that want to benefit of this batching feature must be converted to use the virtio_bus_set_host_notifiers() API. Signed-off-by: Greg Kurz <gr...@kaod.org> --- hw/virtio/virtio-pci.h | 1 + hw/virtio/virtio-pci.c | 53 +++++++++++++++++++++++++++++------------- softmmu/memory.c | 4 ++-- 3 files changed, 40 insertions(+), 18 deletions(-) diff --git a/hw/virtio/virtio-pci.h b/hw/virtio/virtio-pci.h index d7d5d403a948..a1b3f1bc45c9 100644 --- a/hw/virtio/virtio-pci.h +++ b/hw/virtio/virtio-pci.h @@ -141,6 +141,7 @@ struct VirtIOPCIProxy { bool disable_modern; bool ignore_backend_features; OnOffAuto disable_legacy; + bool ioeventfd_assign_started; uint32_t class_code; uint32_t nvectors; uint32_t dfselect; diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c index 883045a22354..0a8738c69541 100644 --- a/hw/virtio/virtio-pci.c +++ b/hw/virtio/virtio-pci.c @@ -243,47 +243,66 @@ static int virtio_pci_ioeventfd_assign(DeviceState *d, EventNotifier *notifier, hwaddr modern_addr = virtio_pci_queue_mem_mult(proxy) * virtio_get_queue_index(vq); hwaddr legacy_addr = VIRTIO_PCI_QUEUE_NOTIFY; + bool transaction = !proxy->ioeventfd_assign_started; if (assign) { if (modern) { if (fast_mmio) { - memory_region_add_eventfd(modern_mr, modern_addr, 0, - false, n, notifier); + memory_region_add_eventfd_full(modern_mr, modern_addr, 0, + false, n, notifier, transaction); } else { - memory_region_add_eventfd(modern_mr, modern_addr, 2, - false, n, notifier); + memory_region_add_eventfd_full(modern_mr, modern_addr, 2, + false, n, notifier, transaction); } if (modern_pio) { - memory_region_add_eventfd(modern_notify_mr, 0, 2, - true, n, notifier); + memory_region_add_eventfd_full(modern_notify_mr, 0, 2, + true, n, notifier, transaction); } } if (legacy) { - memory_region_add_eventfd(legacy_mr, legacy_addr, 2, - true, n, notifier); + memory_region_add_eventfd_full(legacy_mr, legacy_addr, 2, + true, n, notifier, transaction); } } else { if (modern) { if (fast_mmio) { - memory_region_del_eventfd(modern_mr, modern_addr, 0, - false, n, notifier); + memory_region_del_eventfd_full(modern_mr, modern_addr, 0, + false, n, notifier, transaction); } else { - memory_region_del_eventfd(modern_mr, modern_addr, 2, - false, n, notifier); + memory_region_del_eventfd_full(modern_mr, modern_addr, 2, + false, n, notifier, transaction); } if (modern_pio) { - memory_region_del_eventfd(modern_notify_mr, 0, 2, - true, n, notifier); + memory_region_del_eventfd_full(modern_notify_mr, 0, 2, + true, n, notifier, transaction); } } if (legacy) { - memory_region_del_eventfd(legacy_mr, legacy_addr, 2, - true, n, notifier); + memory_region_del_eventfd_full(legacy_mr, legacy_addr, 2, + true, n, notifier, transaction); } } return 0; } +static void virtio_pci_ioeventfd_assign_begin(DeviceState *d) +{ + VirtIOPCIProxy *proxy = to_virtio_pci_proxy(d); + + assert(!proxy->ioeventfd_assign_started); + proxy->ioeventfd_assign_started = true; + memory_region_transaction_begin(); +} + +static void virtio_pci_ioeventfd_assign_commit(DeviceState *d) +{ + VirtIOPCIProxy *proxy = to_virtio_pci_proxy(d); + + assert(proxy->ioeventfd_assign_started); + memory_region_transaction_commit(); + proxy->ioeventfd_assign_started = false; +} + static void virtio_pci_start_ioeventfd(VirtIOPCIProxy *proxy) { virtio_bus_start_ioeventfd(&proxy->bus); @@ -2161,6 +2180,8 @@ static void virtio_pci_bus_class_init(ObjectClass *klass, void *data) k->query_nvectors = virtio_pci_query_nvectors; k->ioeventfd_enabled = virtio_pci_ioeventfd_enabled; k->ioeventfd_assign = virtio_pci_ioeventfd_assign; + k->ioeventfd_assign_begin = virtio_pci_ioeventfd_assign_begin; + k->ioeventfd_assign_commit = virtio_pci_ioeventfd_assign_commit; k->get_dma_as = virtio_pci_get_dma_as; k->queue_enabled = virtio_pci_queue_enabled; } diff --git a/softmmu/memory.c b/softmmu/memory.c index 1b1942d521cc..0279e5671bcb 100644 --- a/softmmu/memory.c +++ b/softmmu/memory.c @@ -2368,7 +2368,7 @@ void memory_region_add_eventfd_full(MemoryRegion *mr, if (size) { adjust_endianness(mr, &mrfd.data, size_memop(size) | MO_TE); } - if (transaction) { + if (!transaction) { memory_region_transaction_begin(); } for (i = 0; i < mr->ioeventfd_nb; ++i) { @@ -2383,7 +2383,7 @@ void memory_region_add_eventfd_full(MemoryRegion *mr, sizeof(*mr->ioeventfds) * (mr->ioeventfd_nb-1 - i)); mr->ioeventfds[i] = mrfd; ioeventfd_update_pending |= mr->enabled; - if (transaction) { + if (!transaction) { memory_region_transaction_commit(); } } -- 2.26.3