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[RFC 4/8] virtio-pci: Batch add/del ioeventfds in a single MR transactio
From: |
Greg Kurz |
Subject: |
[RFC 4/8] virtio-pci: Batch add/del ioeventfds in a single MR transaction |
Date: |
Thu, 25 Mar 2021 16:07:31 +0100 |
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 <groug@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
- [RFC 0/8] virtio: Improve boot time of virtio-scsi-pci and virtio-blk-pci, Greg Kurz, 2021/03/25
- [RFC 2/8] virtio: Introduce virtio_bus_set_host_notifiers(), Greg Kurz, 2021/03/25
- [RFC 4/8] virtio-pci: Batch add/del ioeventfds in a single MR transaction,
Greg Kurz <=
- [RFC 3/8] virtio: Add API to batch set host notifiers, Greg Kurz, 2021/03/25
- Re: [RFC 3/8] virtio: Add API to batch set host notifiers, Stefan Hajnoczi, 2021/03/29
- Re: [RFC 3/8] virtio: Add API to batch set host notifiers, Greg Kurz, 2021/03/30
- Re: [RFC 3/8] virtio: Add API to batch set host notifiers, Stefan Hajnoczi, 2021/03/30
- Re: [RFC 3/8] virtio: Add API to batch set host notifiers, Greg Kurz, 2021/03/30
- Re: [RFC 3/8] virtio: Add API to batch set host notifiers, Stefan Hajnoczi, 2021/03/31
- Re: [RFC 3/8] virtio: Add API to batch set host notifiers, Greg Kurz, 2021/03/31
[RFC 5/8] virtio-blk: Fix rollback path in virtio_blk_data_plane_start(), Greg Kurz, 2021/03/25