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![Rusty Russell](/assets/img/avatar_default.png)
We were cheating with our barriers; using the smp ones rather than the
real device ones. That was fine, until rpmsg came along, which is
used to talk to a real device (a non-SMP CPU).
Unfortunately, just putting back the real barriers (reverting
d57ed95d
) causes a performance regression on virtio-pci. In
particular, Amos reports netbench's TCP_RR over virtio_net CPU
utilization increased up to 35% while throughput went down by up to
14%.
By comparison, this branch is in the noise.
Reference: https://lkml.org/lkml/2011/12/11/22
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
485 lines
13 KiB
C
485 lines
13 KiB
C
/*
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* Virtio memory mapped device driver
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*
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* Copyright 2011, ARM Ltd.
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*
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* This module allows virtio devices to be used over a virtual, memory mapped
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* platform device.
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*
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* Registers layout (all 32-bit wide):
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*
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* offset d. name description
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* ------ -- ---------------- -----------------
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*
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* 0x000 R MagicValue Magic value "virt"
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* 0x004 R Version Device version (current max. 1)
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* 0x008 R DeviceID Virtio device ID
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* 0x00c R VendorID Virtio vendor ID
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*
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* 0x010 R HostFeatures Features supported by the host
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* 0x014 W HostFeaturesSel Set of host features to access via HostFeatures
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*
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* 0x020 W GuestFeatures Features activated by the guest
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* 0x024 W GuestFeaturesSel Set of activated features to set via GuestFeatures
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* 0x028 W GuestPageSize Size of guest's memory page in bytes
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*
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* 0x030 W QueueSel Queue selector
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* 0x034 R QueueNumMax Maximum size of the currently selected queue
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* 0x038 W QueueNum Queue size for the currently selected queue
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* 0x03c W QueueAlign Used Ring alignment for the current queue
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* 0x040 RW QueuePFN PFN for the currently selected queue
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*
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* 0x050 W QueueNotify Queue notifier
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* 0x060 R InterruptStatus Interrupt status register
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* 0x060 W InterruptACK Interrupt acknowledge register
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* 0x070 RW Status Device status register
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*
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* 0x100+ RW Device-specific configuration space
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*
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* Based on Virtio PCI driver by Anthony Liguori, copyright IBM Corp. 2007
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*
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* This work is licensed under the terms of the GNU GPL, version 2 or later.
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* See the COPYING file in the top-level directory.
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*/
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#include <linux/highmem.h>
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#include <linux/interrupt.h>
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#include <linux/io.h>
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#include <linux/list.h>
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#include <linux/module.h>
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#include <linux/platform_device.h>
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#include <linux/slab.h>
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#include <linux/spinlock.h>
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#include <linux/virtio.h>
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#include <linux/virtio_config.h>
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#include <linux/virtio_mmio.h>
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#include <linux/virtio_ring.h>
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/* The alignment to use between consumer and producer parts of vring.
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* Currently hardcoded to the page size. */
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#define VIRTIO_MMIO_VRING_ALIGN PAGE_SIZE
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#define to_virtio_mmio_device(_plat_dev) \
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container_of(_plat_dev, struct virtio_mmio_device, vdev)
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struct virtio_mmio_device {
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struct virtio_device vdev;
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struct platform_device *pdev;
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void __iomem *base;
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unsigned long version;
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/* a list of queues so we can dispatch IRQs */
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spinlock_t lock;
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struct list_head virtqueues;
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};
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struct virtio_mmio_vq_info {
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/* the actual virtqueue */
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struct virtqueue *vq;
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/* the number of entries in the queue */
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unsigned int num;
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/* the index of the queue */
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int queue_index;
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/* the virtual address of the ring queue */
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void *queue;
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/* the list node for the virtqueues list */
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struct list_head node;
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};
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/* Configuration interface */
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static u32 vm_get_features(struct virtio_device *vdev)
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{
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struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
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/* TODO: Features > 32 bits */
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writel(0, vm_dev->base + VIRTIO_MMIO_HOST_FEATURES_SEL);
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return readl(vm_dev->base + VIRTIO_MMIO_HOST_FEATURES);
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}
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static void vm_finalize_features(struct virtio_device *vdev)
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{
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struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
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int i;
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/* Give virtio_ring a chance to accept features. */
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vring_transport_features(vdev);
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for (i = 0; i < ARRAY_SIZE(vdev->features); i++) {
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writel(i, vm_dev->base + VIRTIO_MMIO_GUEST_FEATURES_SEL);
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writel(vdev->features[i],
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vm_dev->base + VIRTIO_MMIO_GUEST_FEATURES);
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}
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}
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static void vm_get(struct virtio_device *vdev, unsigned offset,
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void *buf, unsigned len)
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{
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struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
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u8 *ptr = buf;
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int i;
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for (i = 0; i < len; i++)
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ptr[i] = readb(vm_dev->base + VIRTIO_MMIO_CONFIG + offset + i);
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}
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static void vm_set(struct virtio_device *vdev, unsigned offset,
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const void *buf, unsigned len)
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{
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struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
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const u8 *ptr = buf;
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int i;
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for (i = 0; i < len; i++)
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writeb(ptr[i], vm_dev->base + VIRTIO_MMIO_CONFIG + offset + i);
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}
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static u8 vm_get_status(struct virtio_device *vdev)
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{
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struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
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return readl(vm_dev->base + VIRTIO_MMIO_STATUS) & 0xff;
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}
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static void vm_set_status(struct virtio_device *vdev, u8 status)
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{
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struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
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/* We should never be setting status to 0. */
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BUG_ON(status == 0);
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writel(status, vm_dev->base + VIRTIO_MMIO_STATUS);
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}
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static void vm_reset(struct virtio_device *vdev)
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{
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struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
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/* 0 status means a reset. */
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writel(0, vm_dev->base + VIRTIO_MMIO_STATUS);
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}
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/* Transport interface */
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/* the notify function used when creating a virt queue */
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static void vm_notify(struct virtqueue *vq)
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{
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struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vq->vdev);
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struct virtio_mmio_vq_info *info = vq->priv;
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/* We write the queue's selector into the notification register to
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* signal the other end */
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writel(info->queue_index, vm_dev->base + VIRTIO_MMIO_QUEUE_NOTIFY);
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}
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/* Notify all virtqueues on an interrupt. */
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static irqreturn_t vm_interrupt(int irq, void *opaque)
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{
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struct virtio_mmio_device *vm_dev = opaque;
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struct virtio_mmio_vq_info *info;
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struct virtio_driver *vdrv = container_of(vm_dev->vdev.dev.driver,
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struct virtio_driver, driver);
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unsigned long status;
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unsigned long flags;
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irqreturn_t ret = IRQ_NONE;
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/* Read and acknowledge interrupts */
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status = readl(vm_dev->base + VIRTIO_MMIO_INTERRUPT_STATUS);
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writel(status, vm_dev->base + VIRTIO_MMIO_INTERRUPT_ACK);
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if (unlikely(status & VIRTIO_MMIO_INT_CONFIG)
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&& vdrv && vdrv->config_changed) {
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vdrv->config_changed(&vm_dev->vdev);
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ret = IRQ_HANDLED;
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}
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if (likely(status & VIRTIO_MMIO_INT_VRING)) {
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spin_lock_irqsave(&vm_dev->lock, flags);
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list_for_each_entry(info, &vm_dev->virtqueues, node)
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ret |= vring_interrupt(irq, info->vq);
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spin_unlock_irqrestore(&vm_dev->lock, flags);
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}
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return ret;
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}
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static void vm_del_vq(struct virtqueue *vq)
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{
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struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vq->vdev);
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struct virtio_mmio_vq_info *info = vq->priv;
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unsigned long flags, size;
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spin_lock_irqsave(&vm_dev->lock, flags);
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list_del(&info->node);
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spin_unlock_irqrestore(&vm_dev->lock, flags);
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vring_del_virtqueue(vq);
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/* Select and deactivate the queue */
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writel(info->queue_index, vm_dev->base + VIRTIO_MMIO_QUEUE_SEL);
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writel(0, vm_dev->base + VIRTIO_MMIO_QUEUE_PFN);
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size = PAGE_ALIGN(vring_size(info->num, VIRTIO_MMIO_VRING_ALIGN));
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free_pages_exact(info->queue, size);
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kfree(info);
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}
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static void vm_del_vqs(struct virtio_device *vdev)
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{
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struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
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struct virtqueue *vq, *n;
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list_for_each_entry_safe(vq, n, &vdev->vqs, list)
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vm_del_vq(vq);
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free_irq(platform_get_irq(vm_dev->pdev, 0), vm_dev);
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}
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static struct virtqueue *vm_setup_vq(struct virtio_device *vdev, unsigned index,
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void (*callback)(struct virtqueue *vq),
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const char *name)
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{
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struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
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struct virtio_mmio_vq_info *info;
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struct virtqueue *vq;
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unsigned long flags, size;
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int err;
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/* Select the queue we're interested in */
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writel(index, vm_dev->base + VIRTIO_MMIO_QUEUE_SEL);
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/* Queue shouldn't already be set up. */
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if (readl(vm_dev->base + VIRTIO_MMIO_QUEUE_PFN)) {
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err = -ENOENT;
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goto error_available;
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}
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/* Allocate and fill out our active queue description */
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info = kmalloc(sizeof(*info), GFP_KERNEL);
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if (!info) {
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err = -ENOMEM;
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goto error_kmalloc;
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}
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info->queue_index = index;
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/* Allocate pages for the queue - start with a queue as big as
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* possible (limited by maximum size allowed by device), drop down
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* to a minimal size, just big enough to fit descriptor table
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* and two rings (which makes it "alignment_size * 2")
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*/
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info->num = readl(vm_dev->base + VIRTIO_MMIO_QUEUE_NUM_MAX);
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while (1) {
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size = PAGE_ALIGN(vring_size(info->num,
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VIRTIO_MMIO_VRING_ALIGN));
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/* Already smallest possible allocation? */
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if (size <= VIRTIO_MMIO_VRING_ALIGN * 2) {
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err = -ENOMEM;
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goto error_alloc_pages;
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}
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info->queue = alloc_pages_exact(size, GFP_KERNEL | __GFP_ZERO);
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if (info->queue)
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break;
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info->num /= 2;
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}
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/* Activate the queue */
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writel(info->num, vm_dev->base + VIRTIO_MMIO_QUEUE_NUM);
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writel(VIRTIO_MMIO_VRING_ALIGN,
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vm_dev->base + VIRTIO_MMIO_QUEUE_ALIGN);
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writel(virt_to_phys(info->queue) >> PAGE_SHIFT,
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vm_dev->base + VIRTIO_MMIO_QUEUE_PFN);
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/* Create the vring */
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vq = vring_new_virtqueue(info->num, VIRTIO_MMIO_VRING_ALIGN, vdev,
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true, info->queue, vm_notify, callback, name);
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if (!vq) {
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err = -ENOMEM;
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goto error_new_virtqueue;
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}
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vq->priv = info;
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info->vq = vq;
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spin_lock_irqsave(&vm_dev->lock, flags);
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list_add(&info->node, &vm_dev->virtqueues);
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spin_unlock_irqrestore(&vm_dev->lock, flags);
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return vq;
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error_new_virtqueue:
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writel(0, vm_dev->base + VIRTIO_MMIO_QUEUE_PFN);
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free_pages_exact(info->queue, size);
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error_alloc_pages:
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kfree(info);
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error_kmalloc:
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error_available:
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return ERR_PTR(err);
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}
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static int vm_find_vqs(struct virtio_device *vdev, unsigned nvqs,
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struct virtqueue *vqs[],
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vq_callback_t *callbacks[],
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const char *names[])
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{
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struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
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unsigned int irq = platform_get_irq(vm_dev->pdev, 0);
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int i, err;
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err = request_irq(irq, vm_interrupt, IRQF_SHARED,
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dev_name(&vdev->dev), vm_dev);
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if (err)
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return err;
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for (i = 0; i < nvqs; ++i) {
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vqs[i] = vm_setup_vq(vdev, i, callbacks[i], names[i]);
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if (IS_ERR(vqs[i])) {
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vm_del_vqs(vdev);
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return PTR_ERR(vqs[i]);
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}
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}
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return 0;
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}
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static const char *vm_bus_name(struct virtio_device *vdev)
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{
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struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
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return vm_dev->pdev->name;
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}
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static struct virtio_config_ops virtio_mmio_config_ops = {
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.get = vm_get,
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.set = vm_set,
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.get_status = vm_get_status,
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.set_status = vm_set_status,
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.reset = vm_reset,
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.find_vqs = vm_find_vqs,
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.del_vqs = vm_del_vqs,
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.get_features = vm_get_features,
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.finalize_features = vm_finalize_features,
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.bus_name = vm_bus_name,
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};
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/* Platform device */
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static int __devinit virtio_mmio_probe(struct platform_device *pdev)
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{
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struct virtio_mmio_device *vm_dev;
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struct resource *mem;
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unsigned long magic;
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mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
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if (!mem)
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return -EINVAL;
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if (!devm_request_mem_region(&pdev->dev, mem->start,
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resource_size(mem), pdev->name))
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return -EBUSY;
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vm_dev = devm_kzalloc(&pdev->dev, sizeof(*vm_dev), GFP_KERNEL);
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if (!vm_dev)
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return -ENOMEM;
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vm_dev->vdev.dev.parent = &pdev->dev;
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vm_dev->vdev.config = &virtio_mmio_config_ops;
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vm_dev->pdev = pdev;
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INIT_LIST_HEAD(&vm_dev->virtqueues);
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spin_lock_init(&vm_dev->lock);
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vm_dev->base = devm_ioremap(&pdev->dev, mem->start, resource_size(mem));
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if (vm_dev->base == NULL)
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return -EFAULT;
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/* Check magic value */
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magic = readl(vm_dev->base + VIRTIO_MMIO_MAGIC_VALUE);
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if (memcmp(&magic, "virt", 4) != 0) {
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dev_warn(&pdev->dev, "Wrong magic value 0x%08lx!\n", magic);
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return -ENODEV;
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}
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/* Check device version */
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vm_dev->version = readl(vm_dev->base + VIRTIO_MMIO_VERSION);
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if (vm_dev->version != 1) {
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dev_err(&pdev->dev, "Version %ld not supported!\n",
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vm_dev->version);
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return -ENXIO;
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}
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vm_dev->vdev.id.device = readl(vm_dev->base + VIRTIO_MMIO_DEVICE_ID);
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vm_dev->vdev.id.vendor = readl(vm_dev->base + VIRTIO_MMIO_VENDOR_ID);
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writel(PAGE_SIZE, vm_dev->base + VIRTIO_MMIO_GUEST_PAGE_SIZE);
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platform_set_drvdata(pdev, vm_dev);
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return register_virtio_device(&vm_dev->vdev);
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}
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static int __devexit virtio_mmio_remove(struct platform_device *pdev)
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{
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struct virtio_mmio_device *vm_dev = platform_get_drvdata(pdev);
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unregister_virtio_device(&vm_dev->vdev);
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return 0;
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}
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/* Platform driver */
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static struct of_device_id virtio_mmio_match[] = {
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{ .compatible = "virtio,mmio", },
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{},
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};
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MODULE_DEVICE_TABLE(of, virtio_mmio_match);
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static struct platform_driver virtio_mmio_driver = {
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.probe = virtio_mmio_probe,
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.remove = __devexit_p(virtio_mmio_remove),
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.driver = {
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.name = "virtio-mmio",
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.owner = THIS_MODULE,
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.of_match_table = virtio_mmio_match,
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},
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};
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static int __init virtio_mmio_init(void)
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{
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return platform_driver_register(&virtio_mmio_driver);
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}
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static void __exit virtio_mmio_exit(void)
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{
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platform_driver_unregister(&virtio_mmio_driver);
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}
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module_init(virtio_mmio_init);
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module_exit(virtio_mmio_exit);
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MODULE_AUTHOR("Pawel Moll <pawel.moll@arm.com>");
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MODULE_DESCRIPTION("Platform bus driver for memory mapped virtio devices");
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MODULE_LICENSE("GPL");
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