Re: [Qemu-devel] [PATCH 2/3] vfio: vfio-pci device assignment driver

[Avi Kivity]

On 08/01/2012 08:18 AM, Alex Williamson wrote:
> This adds the core of the QEMU VFIO-based PCI device assignment driver.
> To make use of this driver, enable CONFIG_VFIO, CONFIG_VFIO_IOMMU_TYPE1,
> and CONFIG_VFIO_PCI in your host Linux kernel config.  Load the vfio-pci
> module.  To assign device 0000:05:00.0 to a guest, do the following:
> 
> for dev in $(ls /sys/bus/pci/devices/0000:05:00.0/iommu_group/devices); do
>     vendor=$(cat /sys/bus/pci/devices/$dev/vendor)
>     device=$(cat /sys/bus/pci/devices/$dev/device)
>     if [ -e /sys/bus/pci/devices/$dev/driver ]; then
>         echo $dev > /sys/bus/pci/devices/$dev/driver/unbind
>     fi
>     echo $vendor $device > /sys/bus/pci/drivers/vfio-pci/new_id
> done
> 
> See Documentation/vfio.txt in the Linux kernel tree for further
> description of IOMMU groups and VFIO.
> 
> Then launch qemu including the option:
> 
> -device vfio-pci,host=0000:05:00.0
> 
> Support for legacy PCI interrupts (INTx) is not yet included and will
> be added in a future update.  Both MSI and MSI-X are supported here.


> +
> +static void vfio_update_irq(PCIDevice *pdev)
> +{
> +    VFIODevice *vdev = DO_UPCAST(VFIODevice, pdev, pdev);
> +    PCIINTxRoute route;
> +
> +    if (vdev->interrupt != INT_INTx) {
> +        return;
> +    }
> +
> +    route = pci_device_route_intx_to_irq(&vdev->pdev, vdev->intx.pin);
> +    if (!memcmp(&route, &vdev->intx.route, sizeof(route))) {
> +        return; /* Nothing changed */
> +    }

You can't memcmp() structures, the compiler may add uninitialized holes
that will miscompare.  It's probably harmless here since it's an
optimization.

Unrelated nit: memcmp() doesn't return a boolean or a count, so
!memcmp() is really unintuitive, at least to me.

> +
> +static int vfio_enable_intx(VFIODevice *vdev)
> +{
> +    struct vfio_irq_set_fd irq_set_fd = {
> +        .irq_set = {
> +            .argsz = sizeof(irq_set_fd),
> +            .flags = VFIO_IRQ_SET_DATA_EVENTFD | VFIO_IRQ_SET_ACTION_TRIGGER,
> +            .index = VFIO_PCI_INTX_IRQ_INDEX,
> +            .start = 0,
> +            .count = 1,
> +        },
> +    };
> +    uint8_t pin = vfio_pci_read_config(&vdev->pdev, PCI_INTERRUPT_PIN, 1);
> +
> +    if (!pin) {
> +        return 0;
> +    }
> +
> +    vfio_disable_interrupts(vdev);
> +
> +    vdev->intx.pin = pin - 1; /* Pin A (1) -> irq[0] */
> +    vdev->intx.route = pci_device_route_intx_to_irq(&vdev->pdev,
> +                                                    vdev->intx.pin);
> +    /* TBD - Enable QEMU eoi notifier */
> +
> +    if (event_notifier_init(&vdev->intx.interrupt, 0)) {
> +        error_report("vfio: Error: event_notifier_init failed\n");
> +        return -1;

return -error is better.

> +    }
> +
> +    irq_set_fd.fd = event_notifier_get_fd(&vdev->intx.interrupt);
> +    qemu_set_fd_handler(irq_set_fd.fd, vfio_intx_interrupt, NULL, vdev);
> +
> +    if (ioctl(vdev->fd, VFIO_DEVICE_SET_IRQS, &irq_set_fd)) {
> +        error_report("vfio: Error: Failed to setup INTx fd: %s\n",
> +                     strerror(errno));
> +        return -1;
> +    }
> +
> +    vfio_enable_intx_kvm(vdev);
> +
> +    vdev->interrupt = INT_INTx;
> +
> +    DPRINTF("%s(%04x:%02x:%02x.%x)\n", __func__, vdev->host.domain,
> +            vdev->host.bus, vdev->host.slot, vdev->host.function);
> +
> +    return 0;
> +}
> +
> +
> +
> +/* XXX This should move to msi.c */

Well?

> +static MSIMessage msi_get_msg(PCIDevice *pdev, unsigned int vector)
> +{
> +    uint16_t flags = pci_get_word(pdev->config + pdev->msi_cap + 
> PCI_MSI_FLAGS);
> +    bool msi64bit = flags & PCI_MSI_FLAGS_64BIT;
> +    MSIMessage msg;
> +
> +    if (msi64bit) {
> +        msg.address = pci_get_quad(pdev->config +
> +                                   pdev->msi_cap + PCI_MSI_ADDRESS_LO);
> +    } else {
> +        msg.address = pci_get_long(pdev->config +
> +                                   pdev->msi_cap + PCI_MSI_ADDRESS_LO);
> +    }
> +
> +    msg.data = pci_get_word(pdev->config + pdev->msi_cap +
> +                            (msi64bit ? PCI_MSI_DATA_64 : PCI_MSI_DATA_32));
> +    msg.data += vector;
> +
> +    return msg;
> +}
> +
> +
> +/*
> + * IO Port/MMIO - Beware of the endians, VFIO is always little endian
> + */
> +static void vfio_bar_write(void *opaque, target_phys_addr_t addr,
> +                           uint64_t data, unsigned size)
> +{
> +    VFIOBAR *bar = opaque;
> +    uint8_t buf[8];
> +
> +    switch (size) {
> +    case 1:
> +        *buf = data & 0xff;
> +        break;
> +    case 2:
> +        *(uint16_t *)buf = cpu_to_le16(data);
> +        break;
> +    case 4:
> +        *(uint32_t *)buf = cpu_to_le32(data);
> +        break;

This works accidentally on machines that require alignment, since
there's no requirement from the compiler to align buf.  You can use a
union to align it.

> +    default:
> +        hw_error("vfio: unsupported write size, %d bytes\n", size);
> +        break;
> +    }
> +
> +    if (pwrite(bar->fd, buf, size, bar->fd_offset + addr) != size) {
> +        error_report("%s(,0x%"PRIx64", 0x%"PRIx64", %d) failed: %s\n",
> +                     __func__, addr, data, size, strerror(errno));
> +    }
> +
> +    DPRINTF("%s(BAR%d+0x%"PRIx64", 0x%"PRIx64", %d)\n",
> +            __func__, bar->nr, addr, data, size);
> +}
> +
> +
> +static void vfio_listener_region_add(MemoryListener *listener,
> +                                     MemoryRegionSection *section)
> +{
> +    VFIOContainer *container = container_of(listener, VFIOContainer,
> +                                            iommu_data.listener);
> +    target_phys_addr_t iova, end;
> +    void *vaddr;
> +    int ret;
> +
> +    if (vfio_listener_skipped_section(section)) {
> +        DPRINTF("vfio: SKIPPING region_add %016lx - %016lx\n",
> +                section->offset_within_address_space,
> +                section->offset_within_address_space + section->size - 1);
> +        return;
> +    }
> +
> +    if (unlikely((section->offset_within_address_space & ~TARGET_PAGE_MASK) 
> !=
> +                 (section->offset_within_region & ~TARGET_PAGE_MASK))) {
> +        error_report("%s received unaligned region\n", __func__);

Is it really an error?  I think you can just add the condition to
skipped_section.

> +        return;
> +    }
> +
> +


-- 
error compiling committee.c: too many arguments to function