Multi-queue devices achieve the best performance when each vCPU has a dedicated queue. This ensures that virtqueue used notifications are handled on the same vCPU that submitted virtqueue buffers. When another vCPU handles the the notification an IPI will be necessary to wake the submission vCPU and this incurs a performance overhead. Provide a helper function that virtio-pci devices will use in later patches to automatically select the optimal number of queues. The function handles guests with large numbers of CPUs by limiting the number of queues to fit within the following constraints: 1. The maximum number of MSI-X vectors. 2. The maximum number of virtqueues. Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: Cornelia Huck <cohuck@redhat.com> Message-Id: <20200818143348.310613-4-stefanha@redhat.com> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
256 lines
7.4 KiB
C
256 lines
7.4 KiB
C
/*
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* Virtio PCI Bindings
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*
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* Copyright IBM, Corp. 2007
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* Copyright (c) 2009 CodeSourcery
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*
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* Authors:
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* Anthony Liguori <aliguori@us.ibm.com>
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* Paul Brook <paul@codesourcery.com>
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*
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* This work is licensed under the terms of the GNU GPL, version 2. See
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* the COPYING file in the top-level directory.
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*/
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#ifndef QEMU_VIRTIO_PCI_H
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#define QEMU_VIRTIO_PCI_H
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#include "hw/pci/msi.h"
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#include "hw/virtio/virtio-bus.h"
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typedef struct VirtIOPCIProxy VirtIOPCIProxy;
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/* virtio-pci-bus */
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typedef struct VirtioBusState VirtioPCIBusState;
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typedef struct VirtioBusClass VirtioPCIBusClass;
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#define TYPE_VIRTIO_PCI_BUS "virtio-pci-bus"
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#define VIRTIO_PCI_BUS(obj) \
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OBJECT_CHECK(VirtioPCIBusState, (obj), TYPE_VIRTIO_PCI_BUS)
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#define VIRTIO_PCI_BUS_GET_CLASS(obj) \
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OBJECT_GET_CLASS(VirtioPCIBusClass, obj, TYPE_VIRTIO_PCI_BUS)
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#define VIRTIO_PCI_BUS_CLASS(klass) \
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OBJECT_CLASS_CHECK(VirtioPCIBusClass, klass, TYPE_VIRTIO_PCI_BUS)
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enum {
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VIRTIO_PCI_FLAG_BUS_MASTER_BUG_MIGRATION_BIT,
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VIRTIO_PCI_FLAG_USE_IOEVENTFD_BIT,
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VIRTIO_PCI_FLAG_MIGRATE_EXTRA_BIT,
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VIRTIO_PCI_FLAG_MODERN_PIO_NOTIFY_BIT,
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VIRTIO_PCI_FLAG_DISABLE_PCIE_BIT,
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VIRTIO_PCI_FLAG_PAGE_PER_VQ_BIT,
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VIRTIO_PCI_FLAG_ATS_BIT,
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VIRTIO_PCI_FLAG_INIT_DEVERR_BIT,
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VIRTIO_PCI_FLAG_INIT_LNKCTL_BIT,
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VIRTIO_PCI_FLAG_INIT_PM_BIT,
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VIRTIO_PCI_FLAG_INIT_FLR_BIT,
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};
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/* Need to activate work-arounds for buggy guests at vmstate load. */
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#define VIRTIO_PCI_FLAG_BUS_MASTER_BUG_MIGRATION \
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(1 << VIRTIO_PCI_FLAG_BUS_MASTER_BUG_MIGRATION_BIT)
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/* Performance improves when virtqueue kick processing is decoupled from the
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* vcpu thread using ioeventfd for some devices. */
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#define VIRTIO_PCI_FLAG_USE_IOEVENTFD (1 << VIRTIO_PCI_FLAG_USE_IOEVENTFD_BIT)
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/* virtio version flags */
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#define VIRTIO_PCI_FLAG_DISABLE_PCIE (1 << VIRTIO_PCI_FLAG_DISABLE_PCIE_BIT)
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/* migrate extra state */
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#define VIRTIO_PCI_FLAG_MIGRATE_EXTRA (1 << VIRTIO_PCI_FLAG_MIGRATE_EXTRA_BIT)
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/* have pio notification for modern device ? */
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#define VIRTIO_PCI_FLAG_MODERN_PIO_NOTIFY \
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(1 << VIRTIO_PCI_FLAG_MODERN_PIO_NOTIFY_BIT)
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/* page per vq flag to be used by split drivers within guests */
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#define VIRTIO_PCI_FLAG_PAGE_PER_VQ \
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(1 << VIRTIO_PCI_FLAG_PAGE_PER_VQ_BIT)
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/* address space translation service */
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#define VIRTIO_PCI_FLAG_ATS (1 << VIRTIO_PCI_FLAG_ATS_BIT)
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/* Init error enabling flags */
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#define VIRTIO_PCI_FLAG_INIT_DEVERR (1 << VIRTIO_PCI_FLAG_INIT_DEVERR_BIT)
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/* Init Link Control register */
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#define VIRTIO_PCI_FLAG_INIT_LNKCTL (1 << VIRTIO_PCI_FLAG_INIT_LNKCTL_BIT)
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/* Init Power Management */
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#define VIRTIO_PCI_FLAG_INIT_PM (1 << VIRTIO_PCI_FLAG_INIT_PM_BIT)
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/* Init Function Level Reset capability */
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#define VIRTIO_PCI_FLAG_INIT_FLR (1 << VIRTIO_PCI_FLAG_INIT_FLR_BIT)
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typedef struct {
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MSIMessage msg;
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int virq;
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unsigned int users;
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} VirtIOIRQFD;
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/*
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* virtio-pci: This is the PCIDevice which has a virtio-pci-bus.
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*/
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#define TYPE_VIRTIO_PCI "virtio-pci"
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#define VIRTIO_PCI_GET_CLASS(obj) \
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OBJECT_GET_CLASS(VirtioPCIClass, obj, TYPE_VIRTIO_PCI)
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#define VIRTIO_PCI_CLASS(klass) \
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OBJECT_CLASS_CHECK(VirtioPCIClass, klass, TYPE_VIRTIO_PCI)
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#define VIRTIO_PCI(obj) \
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OBJECT_CHECK(VirtIOPCIProxy, (obj), TYPE_VIRTIO_PCI)
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typedef struct VirtioPCIClass {
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PCIDeviceClass parent_class;
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DeviceRealize parent_dc_realize;
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void (*realize)(VirtIOPCIProxy *vpci_dev, Error **errp);
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} VirtioPCIClass;
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typedef struct VirtIOPCIRegion {
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MemoryRegion mr;
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uint32_t offset;
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uint32_t size;
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uint32_t type;
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} VirtIOPCIRegion;
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typedef struct VirtIOPCIQueue {
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uint16_t num;
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bool enabled;
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uint32_t desc[2];
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uint32_t avail[2];
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uint32_t used[2];
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} VirtIOPCIQueue;
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struct VirtIOPCIProxy {
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PCIDevice pci_dev;
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MemoryRegion bar;
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union {
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struct {
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VirtIOPCIRegion common;
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VirtIOPCIRegion isr;
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VirtIOPCIRegion device;
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VirtIOPCIRegion notify;
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VirtIOPCIRegion notify_pio;
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};
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VirtIOPCIRegion regs[5];
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};
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MemoryRegion modern_bar;
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MemoryRegion io_bar;
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uint32_t legacy_io_bar_idx;
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uint32_t msix_bar_idx;
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uint32_t modern_io_bar_idx;
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uint32_t modern_mem_bar_idx;
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int config_cap;
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uint32_t flags;
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bool disable_modern;
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bool ignore_backend_features;
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OnOffAuto disable_legacy;
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uint32_t class_code;
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uint32_t nvectors;
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uint32_t dfselect;
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uint32_t gfselect;
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uint32_t guest_features[2];
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VirtIOPCIQueue vqs[VIRTIO_QUEUE_MAX];
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VirtIOIRQFD *vector_irqfd;
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int nvqs_with_notifiers;
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VirtioBusState bus;
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};
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static inline bool virtio_pci_modern(VirtIOPCIProxy *proxy)
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{
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return !proxy->disable_modern;
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}
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static inline bool virtio_pci_legacy(VirtIOPCIProxy *proxy)
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{
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return proxy->disable_legacy == ON_OFF_AUTO_OFF;
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}
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static inline void virtio_pci_force_virtio_1(VirtIOPCIProxy *proxy)
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{
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proxy->disable_modern = false;
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proxy->disable_legacy = ON_OFF_AUTO_ON;
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}
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static inline void virtio_pci_disable_modern(VirtIOPCIProxy *proxy)
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{
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proxy->disable_modern = true;
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}
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/*
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* virtio-input-pci: This extends VirtioPCIProxy.
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*/
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#define TYPE_VIRTIO_INPUT_PCI "virtio-input-pci"
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/* Virtio ABI version, if we increment this, we break the guest driver. */
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#define VIRTIO_PCI_ABI_VERSION 0
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/* Input for virtio_pci_types_register() */
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typedef struct VirtioPCIDeviceTypeInfo {
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/*
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* Common base class for the subclasses below.
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*
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* Required only if transitional_name or non_transitional_name is set.
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*
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* We need a separate base type instead of making all types
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* inherit from generic_name for two reasons:
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* 1) generic_name implements INTERFACE_PCIE_DEVICE, but
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* transitional_name does not.
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* 2) generic_name has the "disable-legacy" and "disable-modern"
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* properties, transitional_name and non_transitional name don't.
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*/
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const char *base_name;
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/*
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* Generic device type. Optional.
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*
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* Supports both transitional and non-transitional modes,
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* using the disable-legacy and disable-modern properties.
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* If disable-legacy=auto, (non-)transitional mode is selected
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* depending on the bus where the device is plugged.
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*
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* Implements both INTERFACE_PCIE_DEVICE and INTERFACE_CONVENTIONAL_PCI_DEVICE,
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* but PCI Express is supported only in non-transitional mode.
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*
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* The only type implemented by QEMU 3.1 and older.
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*/
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const char *generic_name;
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/*
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* The transitional device type. Optional.
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*
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* Implements both INTERFACE_PCIE_DEVICE and INTERFACE_CONVENTIONAL_PCI_DEVICE.
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*/
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const char *transitional_name;
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/*
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* The non-transitional device type. Optional.
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*
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* Implements INTERFACE_CONVENTIONAL_PCI_DEVICE only.
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*/
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const char *non_transitional_name;
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/* Parent type. If NULL, TYPE_VIRTIO_PCI is used */
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const char *parent;
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/* Same as TypeInfo fields: */
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size_t instance_size;
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size_t class_size;
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void (*instance_init)(Object *obj);
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void (*class_init)(ObjectClass *klass, void *data);
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InterfaceInfo *interfaces;
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} VirtioPCIDeviceTypeInfo;
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/* Register virtio-pci type(s). @t must be static. */
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void virtio_pci_types_register(const VirtioPCIDeviceTypeInfo *t);
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/**
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* virtio_pci_optimal_num_queues:
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* @fixed_queues: number of queues that are always present
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*
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* Returns: The optimal number of queues for a multi-queue device, excluding
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* @fixed_queues.
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*/
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unsigned virtio_pci_optimal_num_queues(unsigned fixed_queues);
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#endif
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