Re: [Qemu-devel] [PATCH v7 09/16] hw/vfio/platform: add vfio-platform support

[Alexander Graf]

On 05.11.14 13:03, Eric Auger wrote:
> On 11/05/2014 11:29 AM, Alexander Graf wrote:
>>
>>
>> On 31.10.14 15:05, Eric Auger wrote:
>>> Minimal VFIO platform implementation supporting
>>> - register space user mapping,
>>> - IRQ assignment based on eventfds handled on qemu side.
>>>
>>> irqfd kernel acceleration comes in a subsequent patch.
>>>
>>> Signed-off-by: Kim Phillips <address@hidden>
>>> Signed-off-by: Eric Auger <address@hidden>
>>>
>>> ---
>>> v6 -> v7:
>>> - compat is not exposed anymore as a user option. Rationale is
>>>   the vfio device became abstract and a specialization is needed
>>>   anyway. The derived device must set the compat string.
>>> - in v6 vfio_start_irq_injection was exposed in vfio-platform.h.
>>>   A new function dubbed vfio_register_irq_starter replaces it. It
>>>   registers a machine init done notifier that programs & starts
>>>   all dynamic VFIO device IRQs. This function is supposed to be
>>>   called by the machine file. A set of static helper routines are
>>>   added too. It must be called before the creation of the platform
>>>   bus device.
>>>
>>> v5 -> v6:
>>> - vfio_device property renamed into host property
>>> - correct error handling of VFIO_DEVICE_GET_IRQ_INFO ioctl
>>>   and remove PCI related comment
>>> - remove declaration of vfio_setup_irqfd and irqfd_allowed
>>>   property.Both belong to next patch (irqfd)
>>> - remove declaration of vfio_intp_interrupt in vfio-platform.h
>>> - functions that can be static get this characteristic
>>> - remove declarations of vfio_region_ops, vfio_memory_listener,
>>>   group_list, vfio_address_spaces. All are moved to vfio-common.h
>>> - remove vfio_put_device declaration and definition
>>> - print_regions removed. code moved into vfio_populate_regions
>>> - replace DPRINTF by trace events
>>> - new helper routine to set the trigger eventfd
>>> - dissociate intp init from the injection enablement:
>>>   vfio_enable_intp renamed into vfio_init_intp and new function
>>>   named vfio_start_eventfd_injection
>>> - injection start moved to vfio_start_irq_injection (not anymore
>>>   in vfio_populate_interrupt)
>>> - new start_irq_fn field in VFIOPlatformDevice corresponding to
>>>   the function that will be used for starting injection
>>> - user handled eventfd:
>>>   x add mutex to protect IRQ state & list manipulation,
>>>   x correct misleading comment in vfio_intp_interrupt.
>>>   x Fix bugs thanks to fake interrupt modality
>>> - VFIOPlatformDeviceClass becomes abstract
>>> - add error_setg in vfio_platform_realize
>>>
>>> v4 -> v5:
>>> - vfio-plaform.h included first
>>> - cleanup error handling in *populate*, vfio_get_device,
>>>   vfio_enable_intp
>>> - vfio_put_device not called anymore
>>> - add some includes to follow vfio policy
>>>
>>> v3 -> v4:
>>> [Eric Auger]
>>> - merge of "vfio: Add initial IRQ support in platform device"
>>>   to get a full functional patch although perfs are limited.
>>> - removal of unrealize function since I currently understand
>>>   it is only used with device hot-plug feature.
>>>
>>> v2 -> v3:
>>> [Eric Auger]
>>> - further factorization between PCI and platform (VFIORegion,
>>>   VFIODevice). same level of functionality.
>>>
>>> <= v2:
>>> [Kim Philipps]
>>> - Initial Creation of the device supporting register space mapping
>>> ---
>>>  hw/vfio/Makefile.objs           |   1 +
>>>  hw/vfio/platform.c              | 672 
>>> ++++++++++++++++++++++++++++++++++++++++
>>>  include/hw/vfio/vfio-common.h   |   1 +
>>>  include/hw/vfio/vfio-platform.h |  87 ++++++
>>>  trace-events                    |  12 +
>>>  5 files changed, 773 insertions(+)
>>>  create mode 100644 hw/vfio/platform.c
>>>  create mode 100644 include/hw/vfio/vfio-platform.h
>>>
>>> diff --git a/hw/vfio/Makefile.objs b/hw/vfio/Makefile.objs
>>> index e31f30e..c5c76fe 100644
>>> --- a/hw/vfio/Makefile.objs
>>> +++ b/hw/vfio/Makefile.objs
>>> @@ -1,4 +1,5 @@
>>>  ifeq ($(CONFIG_LINUX), y)
>>>  obj-$(CONFIG_SOFTMMU) += common.o
>>>  obj-$(CONFIG_PCI) += pci.o
>>> +obj-$(CONFIG_SOFTMMU) += platform.o
>>>  endif
>>> diff --git a/hw/vfio/platform.c b/hw/vfio/platform.c
>>> new file mode 100644
>>> index 0000000..9f66610
>>> --- /dev/null
>>> +++ b/hw/vfio/platform.c
>>> @@ -0,0 +1,672 @@
>>> +/*
>>> + * vfio based device assignment support - platform devices
>>> + *
>>> + * Copyright Linaro Limited, 2014
>>> + *
>>> + * Authors:
>>> + *  Kim Phillips <address@hidden>
>>> + *
>>> + * This work is licensed under the terms of the GNU GPL, version 2.  See
>>> + * the COPYING file in the top-level directory.
>>> + *
>>> + * Based on vfio based PCI device assignment support:
>>> + *  Copyright Red Hat, Inc. 2012
>>> + */
>>> +
>>> +#include <linux/vfio.h>
>>> +#include <sys/ioctl.h>
>>> +
>>> +#include "hw/vfio/vfio-platform.h"
>>> +#include "qemu/error-report.h"
>>> +#include "qemu/range.h"
>>> +#include "sysemu/sysemu.h"
>>> +#include "exec/memory.h"
>>> +#include "qemu/queue.h"
>>> +#include "hw/sysbus.h"
>>> +#include "trace.h"
>>> +#include "hw/platform-bus.h"
>>> +
>>> +static void vfio_intp_interrupt(VFIOINTp *intp);
>>> +typedef void (*eventfd_user_side_handler_t)(VFIOINTp *intp);
>>> +static int vfio_set_trigger_eventfd(VFIOINTp *intp,
>>> +                                    eventfd_user_side_handler_t handler);
>>> +
>>> +/*
>>> + * Functions only used when eventfd are handled on user-side
>>> + * ie. without irqfd
>>> + */
>>> +
>>> +/**
>>> + * vfio_platform_eoi - IRQ completion routine
>>> + * @vbasedev: the VFIO device
>>> + *
>>> + * de-asserts the active virtual IRQ and unmask the physical IRQ
>>> + * (masked by the  VFIO driver). Handle pending IRQs if any.
>>> + * eoi function is called on the first access to any MMIO region
>>> + * after an IRQ was triggered. It is assumed this access corresponds
>>> + * to the IRQ status register reset. With such a mechanism, a single
>>> + * IRQ can be handled at a time since there is no way to know which
>>> + * IRQ was completed by the guest (we would need additional details
>>> + * about the IRQ status register mask)
>>> + */
>>> +static void vfio_platform_eoi(VFIODevice *vbasedev)
>>> +{
>>> +    VFIOINTp *intp;
>>> +    VFIOPlatformDevice *vdev =
>>> +        container_of(vbasedev, VFIOPlatformDevice, vbasedev);
>>> +
>>> +    qemu_mutex_lock(&vdev->intp_mutex);
>>> +    QLIST_FOREACH(intp, &vdev->intp_list, next) {
>>> +        if (intp->state == VFIO_IRQ_ACTIVE) {
>>> +            trace_vfio_platform_eoi(intp->pin,
>>> +                                event_notifier_get_fd(&intp->interrupt));
>>> +            intp->state = VFIO_IRQ_INACTIVE;
>>> +
>>> +            /* deassert the virtual IRQ and unmask physical one */
>>> +            qemu_set_irq(intp->qemuirq, 0);
>>> +            vfio_unmask_irqindex(vbasedev, intp->pin);
>>> +
>>> +            /* a single IRQ can be active at a time */
>>> +            break;
>>> +        }
>>> +    }
>>> +    /* in case there are pending IRQs, handle them one at a time */
>>> +    if (!QSIMPLEQ_EMPTY(&vdev->pending_intp_queue)) {
>>> +        intp = QSIMPLEQ_FIRST(&vdev->pending_intp_queue);
>>> +        trace_vfio_platform_eoi_handle_pending(intp->pin);
>>> +        qemu_mutex_unlock(&vdev->intp_mutex);
>>> +        vfio_intp_interrupt(intp);
>>> +        qemu_mutex_lock(&vdev->intp_mutex);
>>> +        QSIMPLEQ_REMOVE_HEAD(&vdev->pending_intp_queue, pqnext);
>>> +        qemu_mutex_unlock(&vdev->intp_mutex);
>>> +    } else {
>>> +        qemu_mutex_unlock(&vdev->intp_mutex);
>>> +    }
>>> +}
>>> +
>>> +/**
>>> + * vfio_mmap_set_enabled - enable/disable the fast path mode
>>> + * @vdev: the VFIO platform device
>>> + * @enabled: the target mmap state
>>> + *
>>> + * true ~ fast path = MMIO region is mmaped (no KVM TRAP)
>>> + * false ~ slow path = MMIO region is trapped and region callbacks
>>> + * are called slow path enables to trap the IRQ status register
>>> + * guest reset
>>> +*/
>>> +
>>> +static void vfio_mmap_set_enabled(VFIOPlatformDevice *vdev, bool enabled)
>>> +{
>>> +    VFIORegion *region;
>>> +    int i;
>>> +
>>> +    trace_vfio_platform_mmap_set_enabled(enabled);
>>> +
>>> +    for (i = 0; i < vdev->vbasedev.num_regions; i++) {
>>> +        region = vdev->regions[i];
>>> +
>>> +        /* register space is unmapped to trap EOI */
>>> +        memory_region_set_enabled(&region->mmap_mem, enabled);
>>> +    }
>>> +}
>>> +
>>> +/**
>>> + * vfio_intp_mmap_enable - timer function, restores the fast path
>>> + * if there is no more active IRQ
>>> + * @opaque: actually points to the VFIO platform device
>>> + *
>>> + * Called on mmap timer timout, this function checks whether the
>>> + * IRQ is still active and in the negative restores the fast path.
>>> + * by construction a single eventfd is handled at a time.
>>> + * if the IRQ is still active, the timer is restarted.
>>> + */
>>> +static void vfio_intp_mmap_enable(void *opaque)
>>> +{
>>> +    VFIOINTp *tmp;
>>> +    VFIOPlatformDevice *vdev = (VFIOPlatformDevice *)opaque;
>>> +
>>> +    qemu_mutex_lock(&vdev->intp_mutex);
>>> +    QLIST_FOREACH(tmp, &vdev->intp_list, next) {
>>> +        if (tmp->state == VFIO_IRQ_ACTIVE) {
>>> +            trace_vfio_platform_intp_mmap_enable(tmp->pin);
>>> +            /* re-program the timer to check active status later */
>>> +            timer_mod(vdev->mmap_timer,
>>> +                      qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL) +
>>> +                          vdev->mmap_timeout);
>>> +            qemu_mutex_unlock(&vdev->intp_mutex);
>>> +            return;
>>> +        }
>>> +    }
>>> +    vfio_mmap_set_enabled(vdev, true);
>>> +    qemu_mutex_unlock(&vdev->intp_mutex);
>>> +}
>>> +
>>> +/**
>>> + * vfio_intp_interrupt - The user-side eventfd handler
>>> + * @opaque: opaque pointer which in practice is the VFIOINTp*
>>> + *
>>> + * the function can be entered
>>> + * - in event handler context: this IRQ is inactive
>>> + *   in that case, the vIRQ is injected into the guest if there
>>> + *   is no other active or pending IRQ.
>>> + * - in IOhandler context: this IRQ is pending.
>>> + *   there is no ACTIVE IRQ
>>> + */
>>> +static void vfio_intp_interrupt(VFIOINTp *intp)
>>> +{
>>> +    int ret;
>>> +    VFIOINTp *tmp;
>>> +    VFIOPlatformDevice *vdev = intp->vdev;
>>> +    bool delay_handling = false;
>>> +
>>> +    qemu_mutex_lock(&vdev->intp_mutex);
>>> +    if (intp->state == VFIO_IRQ_INACTIVE) {
>>> +        QLIST_FOREACH(tmp, &vdev->intp_list, next) {
>>> +            if (tmp->state == VFIO_IRQ_ACTIVE ||
>>> +                tmp->state == VFIO_IRQ_PENDING) {
>>> +                delay_handling = true;
>>> +                break;
>>> +            }
>>> +        }
>>> +    }
>>> +    if (delay_handling) {
>>> +        /*
>>> +         * the new IRQ gets a pending status and is pushed in
>>> +         * the pending queue
>>> +         */
>>> +        intp->state = VFIO_IRQ_PENDING;
>>> +        trace_vfio_intp_interrupt_set_pending(intp->pin);
>>> +        QSIMPLEQ_INSERT_TAIL(&vdev->pending_intp_queue,
>>> +                             intp, pqnext);
>>> +        ret = event_notifier_test_and_clear(&intp->interrupt);
>>> +        qemu_mutex_unlock(&vdev->intp_mutex);
>>> +        return;
>>> +    }
>>> +
>>> +    /* no active IRQ, the new IRQ can be forwarded to the guest */
>>> +    trace_vfio_platform_intp_interrupt(intp->pin,
>>> +                              event_notifier_get_fd(&intp->interrupt));
>>> +
>>> +    if (intp->state == VFIO_IRQ_INACTIVE) {
>>> +        ret = event_notifier_test_and_clear(&intp->interrupt);
>>> +        if (!ret) {
>>> +            error_report("Error when clearing fd=%d (ret = %d)\n",
>>> +                         event_notifier_get_fd(&intp->interrupt), ret);
>>> +        }
>>> +    } /* else this is a pending IRQ that moves to ACTIVE state */
>>> +
>>> +    intp->state = VFIO_IRQ_ACTIVE;
>>> +
>>> +    /* sets slow path */
>>> +    vfio_mmap_set_enabled(vdev, false);
>>> +
>>> +    /* trigger the virtual IRQ */
>>> +    qemu_set_irq(intp->qemuirq, 1);
>>> +
>>> +    /* schedule the mmap timer which will restore mmap path after EOI*/
>>> +    if (vdev->mmap_timeout) {
>>> +        timer_mod(vdev->mmap_timer,
>>> +                  qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL) +
>>> +                      vdev->mmap_timeout);
>>> +    }
>>> +    qemu_mutex_unlock(&vdev->intp_mutex);
>>> +}
>>> +
>>> +/**
>>> + * vfio_start_eventfd_injection - starts the virtual IRQ injection using
>>> + * user-side handled eventfds
>>> + * @intp: the IRQ struct pointer
>>> + */
>>> +
>>> +static int vfio_start_eventfd_injection(VFIOINTp *intp)
>>> +{
>>> +    int ret;
>>> +    VFIODevice *vbasedev = &intp->vdev->vbasedev;
>>> +
>>> +    vfio_mask_irqindex(vbasedev, intp->pin);
>>> +
>>> +    ret = vfio_set_trigger_eventfd(intp, vfio_intp_interrupt);
>>> +    if (ret) {
>>> +        error_report("vfio: Error: Failed to pass IRQ fd to the driver: 
>>> %m");
>>> +        vfio_unmask_irqindex(vbasedev, intp->pin);
>>> +        return ret;
>>> +    }
>>> +    vfio_unmask_irqindex(vbasedev, intp->pin);
>>> +    return 0;
>>> +}
>>> +
>>> +/*
>>> + * Functions used whatever the injection method
>>> + */
>>> +
>>> +/**
>>> + * vfio_set_trigger_eventfd - set VFIO eventfd handling
>>> + * ie. program the VFIO driver to associates a given IRQ index
>>> + * with a fd handler
>>> + *
>>> + * @intp: IRQ struct pointer
>>> + * @handler: handler to be called on eventfd trigger
>>> + */
>>> +static int vfio_set_trigger_eventfd(VFIOINTp *intp,
>>> +                                    eventfd_user_side_handler_t handler)
>>> +{
>>> +    VFIODevice *vbasedev = &intp->vdev->vbasedev;
>>> +    struct vfio_irq_set *irq_set;
>>> +    int argsz, ret;
>>> +    int32_t *pfd;
>>> +
>>> +    argsz = sizeof(*irq_set) + sizeof(*pfd);
>>> +    irq_set = g_malloc0(argsz);
>>> +    irq_set->argsz = argsz;
>>> +    irq_set->flags = VFIO_IRQ_SET_DATA_EVENTFD | 
>>> VFIO_IRQ_SET_ACTION_TRIGGER;
>>> +    irq_set->index = intp->pin;
>>> +    irq_set->start = 0;
>>> +    irq_set->count = 1;
>>> +    pfd = (int32_t *)&irq_set->data;
>>> +    *pfd = event_notifier_get_fd(&intp->interrupt);
>>> +    qemu_set_fd_handler(*pfd, (IOHandler *)handler, NULL, intp);
>>> +    ret = ioctl(vbasedev->fd, VFIO_DEVICE_SET_IRQS, irq_set);
>>> +    g_free(irq_set);
>>> +    if (ret < 0) {
>>> +        error_report("vfio: Failed to set trigger eventfd: %m");
>>> +        qemu_set_fd_handler(*pfd, NULL, NULL, NULL);
>>> +    }
>>> +    return ret;
>>> +}
>>> +
>>> +/* not implemented yet */
>>> +static bool vfio_platform_compute_needs_reset(VFIODevice *vdev)
>>> +{
>>> +return false;
>>> +}
>>> +
>>> +/* not implemented yet */
>>> +static int vfio_platform_hot_reset_multi(VFIODevice *vdev)
>>> +{
>>> +return 0;
>>> +}
>>> +
>>> +/**
>>> + * vfio_init_intp - allocate, initialize the IRQ struct pointer
>>> + * and add it into the list of IRQ
>>> + * @vbasedev: the VFIO device
>>> + * @index: VFIO device IRQ index
>>> + */
>>> +static VFIOINTp *vfio_init_intp(VFIODevice *vbasedev, unsigned int index)
>>> +{
>>> +    int ret;
>>> +    VFIOPlatformDevice *vdev =
>>> +        container_of(vbasedev, VFIOPlatformDevice, vbasedev);
>>> +    SysBusDevice *sbdev = SYS_BUS_DEVICE(vdev);
>>> +    VFIOINTp *intp;
>>> +
>>> +    /* allocate and populate a new VFIOINTp structure put in a queue list 
>>> */
>>> +    intp = g_malloc0(sizeof(*intp));
>>> +    intp->vdev = vdev;
>>> +    intp->pin = index;
>>> +    intp->state = VFIO_IRQ_INACTIVE;
>>> +    sysbus_init_irq(sbdev, &intp->qemuirq);
>>> +
>>> +    /* Get an eventfd for trigger */
>>> +    ret = event_notifier_init(&intp->interrupt, 0);
>>> +    if (ret) {
>>> +        g_free(intp);
>>> +        error_report("vfio: Error: trigger event_notifier_init failed ");
>>> +        return NULL;
>>> +    }
>>> +
>>> +    /* store the new intp in qlist */
>>> +    QLIST_INSERT_HEAD(&vdev->intp_list, intp, next);
>>> +    return intp;
>>> +}
>>> +
>>> +/**
>>> + * vfio_populate_device - initialize MMIO region and IRQ
>>> + * @vbasedev: the VFIO device
>>> + *
>>> + * query the VFIO device for exposed MMIO regions and IRQ and
>>> + * populate the associated fields in the device struct
>>> + */
>>> +static int vfio_populate_device(VFIODevice *vbasedev)
>>> +{
>>> +    struct vfio_irq_info irq = { .argsz = sizeof(irq) };
>>> +    struct vfio_region_info reg_info = { .argsz = sizeof(reg_info) };
>>> +    VFIOINTp *intp;
>>> +    int i, ret = 0;
>>> +    VFIOPlatformDevice *vdev =
>>> +        container_of(vbasedev, VFIOPlatformDevice, vbasedev);
>>> +
>>> +    vdev->regions = g_malloc0(sizeof(VFIORegion *) * 
>>> vbasedev->num_regions);
>>> +
>>> +    for (i = 0; i < vbasedev->num_regions; i++) {
>>> +        vdev->regions[i] = g_malloc0(sizeof(VFIORegion));
>>> +        reg_info.index = i;
>>> +        ret = ioctl(vbasedev->fd, VFIO_DEVICE_GET_REGION_INFO, &reg_info);
>>> +        if (ret) {
>>> +            error_report("vfio: Error getting region %d info: %m", i);
>>> +            goto error;
>>> +        }
>>> +        vdev->regions[i]->flags = reg_info.flags;
>>> +        vdev->regions[i]->size = reg_info.size;
>>> +        vdev->regions[i]->fd_offset = reg_info.offset;
>>> +        vdev->regions[i]->nr = i;
>>> +        vdev->regions[i]->vbasedev = vbasedev;
>>> +
>>> +        trace_vfio_platform_populate_regions(vdev->regions[i]->nr,
>>> +                            (unsigned long)vdev->regions[i]->flags,
>>> +                            (unsigned long)vdev->regions[i]->size,
>>> +                            vdev->regions[i]->vbasedev->fd,
>>> +                            (unsigned long)vdev->regions[i]->fd_offset);
>>> +    }
>>> +
>>> +    vdev->mmap_timer = timer_new_ms(QEMU_CLOCK_VIRTUAL,
>>> +                                    vfio_intp_mmap_enable, vdev);
>>> +
>>> +    QSIMPLEQ_INIT(&vdev->pending_intp_queue);
>>> +
>>> +    for (i = 0; i < vbasedev->num_irqs; i++) {
>>> +        irq.index = i;
>>> +
>>> +        ret = ioctl(vbasedev->fd, VFIO_DEVICE_GET_IRQ_INFO, &irq);
>>> +        if (ret) {
>>> +            error_printf("vfio: error getting device %s irq info",
>>> +                         vbasedev->name);
>>> +            return ret;
>>> +        } else {
>>> +            trace_vfio_platform_populate_interrupts(irq.index,
>>> +                                                    irq.count,
>>> +                                                    irq.flags);
>>> +            intp = vfio_init_intp(vbasedev, irq.index);
>>> +            if (!intp) {
>>> +                error_report("vfio: Error installing IRQ %d up", i);
>>> +                return ret;
>>> +            }
>>> +        }
>>> +    }
>>> +    return 0;
>>> +error:
>>> +    return ret;
>>> +}
>>> +
>>> +/*
>>> + * vfio_start_irq_injection - associates a virtual irq to a
>>> + * VFIO IRQ index and start the injection of this IRQ
>>> + * @s: SysBus Device
>>> + * @index: VFIO IRQ index
>>> + * @virq: the virtual IRQ number, aka gsi
>>> + *
>>> + * this function is called when the device tree is built
>>> + */
>>> +static void vfio_start_irq_injection(SysBusDevice *s, int index, int virq)
>>> +{
>>> +    VFIOPlatformDevice *vdev = container_of(s, VFIOPlatformDevice, sbdev);
>>> +    VFIOINTp *intp;
>>> +
>>> +    QLIST_FOREACH(intp, &vdev->intp_list, next) {
>>> +        if (intp->pin == index) {
>>> +            intp->virtualID = virq;
>>> +            vdev->start_irq_fn(intp);
>>> +        }
>>> +    }
>>> +}
>>> +
>>> +/* specialized functions ofr VFIO Platform devices */
>>> +static VFIODeviceOps vfio_platform_ops = {
>>> +    .vfio_compute_needs_reset = vfio_platform_compute_needs_reset,
>>> +    .vfio_hot_reset_multi = vfio_platform_hot_reset_multi,
>>> +    .vfio_eoi = vfio_platform_eoi,
>>> +    .vfio_populate_device = vfio_populate_device,
>>> +};
>>> +
>>> +/**
>>> + * vfio_base_device_init - implements some of the VFIO mechanics
>>> + * @vbasedev: the VFIO device
>>> + *
>>> + * retrieves the group the device belongs to and get the device fd
>>> + * returns the VFIO device fd
>>> + * precondition: the device name must be initialized
>>> + */
>>> +static int vfio_base_device_init(VFIODevice *vbasedev)
>>> +{
>>> +    VFIOGroup *group;
>>> +    VFIODevice *vbasedev_iter;
>>> +    char path[PATH_MAX], iommu_group_path[PATH_MAX], *group_name;
>>> +    ssize_t len;
>>> +    struct stat st;
>>> +    int groupid;
>>> +    int ret;
>>> +
>>> +    /* name must be set prior to the call */
>>> +    if (!vbasedev->name) {
>>> +        return -EINVAL;
>>> +    }
>>> +
>>> +    /* Check that the host device exists */
>>> +    snprintf(path, sizeof(path), "/sys/bus/platform/devices/%s/",
>>> +             vbasedev->name);
>>> +
>>> +    if (stat(path, &st) < 0) {
>>> +        error_report("vfio: error: no such host device: %s", path);
>>> +        return -errno;
>>> +    }
>>> +
>>> +    strncat(path, "iommu_group", sizeof(path) - strlen(path) - 1);
>>> +    len = readlink(path, iommu_group_path, sizeof(path));
>>> +    if (len <= 0 || len >= sizeof(path)) {
>>> +        error_report("vfio: error no iommu_group for device");
>>> +        return len < 0 ? -errno : ENAMETOOLONG;
>>> +    }
>>> +
>>> +    iommu_group_path[len] = 0;
>>> +    group_name = basename(iommu_group_path);
>>> +
>>> +    if (sscanf(group_name, "%d", &groupid) != 1) {
>>> +        error_report("vfio: error reading %s: %m", path);
>>> +        return -errno;
>>> +    }
>>> +
>>> +    trace_vfio_platform_base_device_init(vbasedev->name, groupid);
>>> +
>>> +    group = vfio_get_group(groupid, &address_space_memory);
>>> +    if (!group) {
>>> +        error_report("vfio: failed to get group %d", groupid);
>>> +        return -ENOENT;
>>> +    }
>>> +
>>> +    snprintf(path, sizeof(path), "%s", vbasedev->name);
>>> +
>>> +    QLIST_FOREACH(vbasedev_iter, &group->device_list, next) {
>>> +        if (strcmp(vbasedev_iter->name, vbasedev->name) == 0) {
>>> +            error_report("vfio: error: device %s is already attached", 
>>> path);
>>> +            vfio_put_group(group);
>>> +            return -EBUSY;
>>> +        }
>>> +    }
>>> +    ret = vfio_get_device(group, path, vbasedev);
>>> +    if (ret) {
>>> +        error_report("vfio: failed to get device %s", path);
>>> +        vfio_put_group(group);
>>> +    }
>>> +    return ret;
>>> +}
>>> +
>>> +/**
>>> + * vfio_map_region - initialize the 2 mr (mmapped on ops) for a
>>> + * given index
>>> + * @vdev: the VFIO platform device
>>> + * @nr: the index of the region
>>> + *
>>> + * init the top memory region and the mmapped memroy region beneath
>>> + * VFIOPlatformDevice is used since VFIODevice is not a QOM Object
>>> + * and could not be passed to memory region functions
>>> +*/
>>> +static void vfio_map_region(VFIOPlatformDevice *vdev, int nr)
>>> +{
>>> +    VFIORegion *region = vdev->regions[nr];
>>> +    unsigned size = region->size;
>>> +    char name[64];
>>> +
>>> +    if (!size) {
>>> +        return;
>>> +    }
>>> +
>>> +    snprintf(name, sizeof(name), "VFIO %s region %d",
>>> +             vdev->vbasedev.name, nr);
>>> +
>>> +    /* A "slow" read/write mapping underlies all regions */
>>> +    memory_region_init_io(&region->mem, OBJECT(vdev), &vfio_region_ops,
>>> +                          region, name, size);
>>> +
>>> +    strncat(name, " mmap", sizeof(name) - strlen(name) - 1);
>>> +
>>> +    if (vfio_mmap_region(OBJECT(vdev), region, &region->mem,
>>> +                         &region->mmap_mem, &region->mmap, size, 0, name)) 
>>> {
>>> +        error_report("%s unsupported. Performance may be slow", name);
>>> +    }
>>> +}
>>> +
>>> +/**
>>> + * vfio_platform_realize  - the device realize function
>>> + * @dev: device state pointer
>>> + * @errp: error
>>> + *
>>> + * initialize the device, its memory regions and IRQ structures
>>> + * IRQ are started separately
>>> + */
>>> +static void vfio_platform_realize(DeviceState *dev, Error **errp)
>>> +{
>>> +    VFIOPlatformDevice *vdev = VFIO_PLATFORM_DEVICE(dev);
>>> +    SysBusDevice *sbdev = SYS_BUS_DEVICE(dev);
>>> +    VFIODevice *vbasedev = &vdev->vbasedev;
>>> +    int i, ret;
>>> +
>>> +    vbasedev->type = VFIO_DEVICE_TYPE_PLATFORM;
>>> +    vbasedev->ops = &vfio_platform_ops;
>>> +    vdev->start_irq_fn = vfio_start_eventfd_injection;
>>> +
>>> +    trace_vfio_platform_realize(vbasedev->name, vdev->compat);
>>> +
>>> +    ret = vfio_base_device_init(vbasedev);
>>> +    if (ret) {
>>> +        error_setg(errp, "vfio: vfio_base_device_init failed for %s",
>>> +                   vbasedev->name);
>>> +        return;
>>> +    }
>>> +
>>> +    for (i = 0; i < vbasedev->num_regions; i++) {
>>> +        vfio_map_region(vdev, i);
>>> +        sysbus_init_mmio(sbdev, &vdev->regions[i]->mem);
>>> +    }
>>> +}
>>> +
>>> +/*
>>> + * Mechanics to program/start irq injection on machine init done notifier:
>>> + * this is needed since at finalize time, the device IRQ are not yet
>>> + * bound to the platform bus IRQ. It is assumed here dynamic instantiation
>>> + * always is used. Binding to the platform bus IRQ happens on a machine
>>> + * init done notifier registered by the machine file. After its execution
>>> + * we execute a new notifier that actually starts the injection. When using
>>> + * irqfd, programming the injection consists in associating eventfds to
>>> + * GSI number,ie. virtual IRQ number
>>> + */
>>> +
>>> +typedef struct VfioIrqStarterNotifierParams {
>>> +    unsigned int platform_bus_first_irq;
>>> +    Notifier notifier;
>>> +} VfioIrqStarterNotifierParams;
>>> +
>>> +typedef struct VfioIrqStartParams {
>>> +    PlatformBusDevice *pbus;
>>> +    int platform_bus_first_irq;
>>> +} VfioIrqStartParams;
>>> +
>>> +/* Start injection of IRQ for a specific VFIO device */
>>> +static int vfio_irq_starter(SysBusDevice *sbdev, void *opaque)
>>> +{
>>> +    int i;
>>> +    VfioIrqStartParams *p = opaque;
>>> +    VFIOPlatformDevice *vdev;
>>> +    VFIODevice *vbasedev;
>>> +    uint64_t irq_number;
>>> +    PlatformBusDevice *pbus = p->pbus;
>>> +    int platform_bus_first_irq = p->platform_bus_first_irq;
>>> +
>>> +    if (object_dynamic_cast(OBJECT(sbdev), TYPE_VFIO_PLATFORM)) {
>>> +        vdev = VFIO_PLATFORM_DEVICE(sbdev);
>>> +        vbasedev = &vdev->vbasedev;
>>> +        for (i = 0; i < vbasedev->num_irqs; i++) {
>>> +            irq_number = platform_bus_get_irqn(pbus, sbdev, i)
>>> +                             + platform_bus_first_irq;
>>> +            vfio_start_irq_injection(sbdev, i, irq_number);
>>> +        }
>>> +    }
>>> +    return 0;
>>> +}
>>> +
>>> +/* loop on all VFIO platform devices and start their IRQ injection */
>>> +static void vfio_irq_starter_notify(Notifier *notifier, void *data)
>>> +{
>>> +    VfioIrqStarterNotifierParams *p =
>>> +        container_of(notifier, VfioIrqStarterNotifierParams, notifier);
>>> +    DeviceState *dev =
>>> +        qdev_find_recursive(sysbus_get_default(), 
>>> TYPE_PLATFORM_BUS_DEVICE);
>>> +    PlatformBusDevice *pbus = PLATFORM_BUS_DEVICE(dev);
>>> +
>>> +    if (pbus->done_gathering) {
>>> +        VfioIrqStartParams data = {
>>> +            .pbus = pbus,
>>> +            .platform_bus_first_irq = p->platform_bus_first_irq,
>>> +        };
>>> +
>>> +        foreach_dynamic_sysbus_device(vfio_irq_starter, &data);
>>> +    }
>>> +}
>>> +
>>> +/* registers the machine init done notifier that will start VFIO IRQ */
>>> +void vfio_register_irq_starter(int platform_bus_first_irq)
>>> +{
>>> +    VfioIrqStarterNotifierParams *p = g_new(VfioIrqStarterNotifierParams, 
>>> 1);
>>> +
>>> +    p->platform_bus_first_irq = platform_bus_first_irq;
>>> +    p->notifier.notify = vfio_irq_starter_notify;
>>> +    qemu_add_machine_init_done_notifier(&p->notifier);
>>
>> Could you add a notifier for each device instead? Then the notifier
>> would be part of the vfio device struct and not some dangling random
>> pointer :).
>>
>> Of course instead of foreach_dynamic_sysbus_device() you would directly
>> know the device you're dealing with and only handle a single device per
>> notifier.
> 
> Hi Alex,
> 
> Indeed I can do that and put the foreach in the machine file instead.
> This means however more code in virt.c, in the create_platform_bus
> function. If Peter agrees with that I will proceed.
> 
> I take the opportunity to ask a question I did not dare to ask yet about
> qemu_irq ;-). Wouldn't it make sense to create an accessor to be able to
> retrieve the IRQ number (n field). Indeed I currently do some gym to
> pass the platform bus first irq and it would be definitively simpler to
> directly retrieve n from qemu_irq. Besides I think we also have this
> need when setting up irqfd for vhost net to associate the gsi with guest
> notifier.

No, a qemu_irq object only knows the connection it establishes. The
bigger picture of what number it has is bus / machine specific. That's
what I added the easy platform_bus_get_irqn() helper for ;).


Alex