Re: [Qemu-devel] [RFC v4 06/13] hw/vfio/pci: split vfio_get_device

[Eric Auger]

On 07/09/2014 12:43 AM, Alex Williamson wrote:
> On Mon, 2014-07-07 at 13:27 +0100, Eric Auger wrote:
>> vfio_get_device now takes a VFIODevice as argument. The function is split
>> into 4 functional parts: dev_info query, device check, region populate
>> and interrupt populate. the last 3 are specialized by parent device and
>> are added into DeviceOps.
>>
>> 3 new fields are introduced in VFIODevice to store dev_info.
>>
>> vfio_put_base_device is created.
>>
>> Signed-off-by: Eric Auger <address@hidden>
>> ---
>>  hw/vfio/pci.c | 181 
>> +++++++++++++++++++++++++++++++++++++++-------------------
>>  1 file changed, 121 insertions(+), 60 deletions(-)
>>
>> diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
>> index 5f0164a..d228cf8 100644
>> --- a/hw/vfio/pci.c
>> +++ b/hw/vfio/pci.c
>> @@ -194,12 +194,18 @@ typedef struct VFIODevice {
>>      bool reset_works;
>>      bool needs_reset;
>>      VFIODeviceOps *ops;
>> +    unsigned int num_irqs;
>> +    unsigned int num_regions;
>> +    unsigned int flags;
>>  } VFIODevice;
>>  
>>  struct VFIODeviceOps {
>>      bool (*vfio_compute_needs_reset)(VFIODevice *vdev);
>>      int (*vfio_hot_reset_multi)(VFIODevice *vdev);
>>      void (*vfio_eoi)(VFIODevice *vdev);
>> +    int (*vfio_check_device)(VFIODevice *vdev);
>> +    int (*vfio_populate_regions)(VFIODevice *vdev);
>> +    int (*vfio_populate_interrupts)(VFIODevice *vdev);
>>  };
>>  
>>  typedef struct VFIOPCIDevice {
>> @@ -286,6 +292,10 @@ static uint32_t vfio_pci_read_config(PCIDevice *pdev, 
>> uint32_t addr, int len);
>>  static void vfio_pci_write_config(PCIDevice *pdev, uint32_t addr,
>>                                    uint32_t val, int len);
>>  static void vfio_mmap_set_enabled(VFIOPCIDevice *vdev, bool enabled);
>> +static void vfio_put_base_device(VFIODevice *vbasedev);
>> +static int vfio_check_device(VFIODevice *vbasedev);
>> +static int vfio_populate_regions(VFIODevice *vbasedev);
>> +static int vfio_populate_interrupts(VFIODevice *vbasedev);
>>  
>>  /*
>>   * Common VFIO interrupt disable
>> @@ -3585,6 +3595,9 @@ static VFIODeviceOps vfio_pci_ops = {
>>      .vfio_compute_needs_reset = vfio_pci_compute_needs_reset,
>>      .vfio_hot_reset_multi = vfio_pci_hot_reset_multi,
>>      .vfio_eoi = vfio_eoi,
>> +    .vfio_check_device = vfio_check_device,
>> +    .vfio_populate_regions = vfio_populate_regions,
>> +    .vfio_populate_interrupts = vfio_populate_interrupts,
>>  };
>>  
>>  static void vfio_reset_handler(void *opaque)
>> @@ -3927,54 +3940,53 @@ static void vfio_put_group(VFIOGroup *group)
>>      }
>>  }
>>  
>> -static int vfio_get_device(VFIOGroup *group, const char *name,
>> -                           VFIOPCIDevice *vdev)
>> +static int vfio_check_device(VFIODevice *vbasedev)
>>  {
>> -    struct vfio_device_info dev_info = { .argsz = sizeof(dev_info) };
>> -    struct vfio_region_info reg_info = { .argsz = sizeof(reg_info) };
>> -    struct vfio_irq_info irq_info = { .argsz = sizeof(irq_info) };
>> -    int ret, i;
>> -
>> -    ret = ioctl(group->fd, VFIO_GROUP_GET_DEVICE_FD, name);
>> -    if (ret < 0) {
>> -        error_report("vfio: error getting device %s from group %d: %m",
>> -                     name, group->groupid);
>> -        error_printf("Verify all devices in group %d are bound to vfio-pci "
>> -                     "or pci-stub and not already in use\n", 
>> group->groupid);
>> -        return ret;
>> +    if (!(vbasedev->flags & VFIO_DEVICE_FLAGS_PCI)) {
>> +        error_report("vfio: Um, this isn't a PCI device");
>> +        goto error;
>>      }
>> -
>> -    vdev->vbasedev.fd = ret;
>> -    vdev->vbasedev.group = group;
>> -    QLIST_INSERT_HEAD(&group->device_list, &vdev->vbasedev, next);
>> -
>> -    /* Sanity check device */
>> -    ret = ioctl(vdev->vbasedev.fd, VFIO_DEVICE_GET_INFO, &dev_info);
>> -    if (ret) {
>> -        error_report("vfio: error getting device info: %m");
>> +    if (vbasedev->num_regions < VFIO_PCI_CONFIG_REGION_INDEX + 1) {
>> +        error_report("vfio: unexpected number of io regions %u",
>> +                     vbasedev->num_regions);
>>          goto error;
>>      }
>> -
>> -    DPRINTF("Device %s flags: %u, regions: %u, irgs: %u\n", name,
>> -            dev_info.flags, dev_info.num_regions, dev_info.num_irqs);
>> -
>> -    if (!(dev_info.flags & VFIO_DEVICE_FLAGS_PCI)) {
>> -        error_report("vfio: Um, this isn't a PCI device");
>> +    if (vbasedev->num_irqs < VFIO_PCI_MSIX_IRQ_INDEX + 1) {
>> +        error_report("vfio: unexpected number of irqs %u",
>> +                     vbasedev->num_irqs);
>>          goto error;
>>      }
>> +   return 0;
>> +error:
>> +    vfio_put_base_device(vbasedev);
> 
> This doesn't make much sense, this function never "got" the base device,
> so why does it need to "put" it on error?  We should simply return error
> and the caller (presumably who got it) should put the device.
Hi Alex,

definitively I need to revisit and homogenize my error handling: all
sub-functions just returning errors - if sensible- , get/put at upper
level. errno misusage. Sorry for that :-(
> 
>> +    return -errno;
> 
> Nothing above seems to guarantee we have anything useful in errno (or
> that it hasn't been clobbered).
replaced by -1
> 
>> +}
>>  
>> -    vdev->vbasedev.reset_works = !!(dev_info.flags & 
>> VFIO_DEVICE_FLAGS_RESET);
>> +static int vfio_populate_interrupts(VFIODevice *vbasedev)
>> +{
>> +    VFIOPCIDevice *vdev = container_of(vbasedev, VFIOPCIDevice, vbasedev);
>> +    int ret;
>> +    struct vfio_irq_info irq_info = { .argsz = sizeof(irq_info) };
>> +    irq_info.index = VFIO_PCI_ERR_IRQ_INDEX;
>>  
>> -    if (dev_info.num_regions < VFIO_PCI_CONFIG_REGION_INDEX + 1) {
>> -        error_report("vfio: unexpected number of io regions %u",
>> -                     dev_info.num_regions);
>> -        goto error;
>> +    ret = ioctl(vbasedev->fd, VFIO_DEVICE_GET_IRQ_INFO, &irq_info);
>> +    if (ret) {
>> +        /* This can fail for an old kernel or legacy PCI dev */
>> +        DPRINTF("VFIO_DEVICE_GET_IRQ_INFO failure: %m\n");
>> +    } else if (irq_info.count == 1) {
>> +        vdev->pci_aer = true;
>> +    } else {
>> +        error_report("vfio: %s Could not enable error recovery for the 
>> device",
>> +                     vbasedev->name);
>>      }
>> +    return ret;
> 
> This function returns error if the device doesn't support error
> reporting, which is an optional feature.  I don't think that's what we
> want.
OK misunderstood the comment. function proto changed to return void.
> 
>> +}
>>  
>> -    if (dev_info.num_irqs < VFIO_PCI_MSIX_IRQ_INDEX + 1) {
>> -        error_report("vfio: unexpected number of irqs %u", 
>> dev_info.num_irqs);
>> -        goto error;
>> -    }
>> +static int vfio_populate_regions(VFIODevice *vbasedev)
>> +{
>> +    struct vfio_region_info reg_info = { .argsz = sizeof(reg_info) };
>> +    int i, ret;
>> +    VFIOPCIDevice *vdev = container_of(vbasedev, VFIOPCIDevice, vbasedev);
>>  
>>      for (i = VFIO_PCI_BAR0_REGION_INDEX; i < VFIO_PCI_ROM_REGION_INDEX; 
>> i++) {
>>          reg_info.index = i;
>> @@ -4018,7 +4030,7 @@ static int vfio_get_device(VFIOGroup *group, const 
>> char *name,
>>      vdev->config_offset = reg_info.offset;
>>  
>>      if ((vdev->features & VFIO_FEATURE_ENABLE_VGA) &&
>> -        dev_info.num_regions > VFIO_PCI_VGA_REGION_INDEX) {
>> +        vbasedev->num_regions > VFIO_PCI_VGA_REGION_INDEX) {
>>          struct vfio_region_info vga_info = {
>>              .argsz = sizeof(vga_info),
>>              .index = VFIO_PCI_VGA_REGION_INDEX,
>> @@ -4057,38 +4069,87 @@ static int vfio_get_device(VFIOGroup *group, const 
>> char *name,
>>  
>>          vdev->has_vga = true;
>>      }
>> -    irq_info.index = VFIO_PCI_ERR_IRQ_INDEX;
>> +    return 0;
>> +error:
>> +    vfio_put_base_device(vbasedev);
>> +    return -errno;
> 
> errno can get clobbered by here, don't count on it.  Also, why does this
> put the base device while interrupt_populate error does not?  The put
> needs to happen a level above these functions imho.

ok
> 
>> +}
>> +
>> +static int vfio_get_device(VFIOGroup *group, const char *name,
>> +                           VFIODevice *vbasedev)
>> +{
>> +    struct vfio_device_info dev_info = { .argsz = sizeof(dev_info) };
>> +    struct vfio_region_info reg_info = { .argsz = sizeof(reg_info) };
>> +    struct vfio_irq_info irq_info = { .argsz = sizeof(irq_info) };
>> +    int ret;
>> +
>> +    ret = ioctl(group->fd, VFIO_GROUP_GET_DEVICE_FD, name);
>> +    if (ret < 0) {
>> +        error_report("vfio: error getting device %s from group %d: %m",
>> +                     name, group->groupid);
>> +        error_printf("Verify all devices in group %d are bound to vfio-pci "
>> +                     "or pci-stub and not already in use\n", 
>> group->groupid);
>> +        return ret;
>> +    }
>> +
>> +    vbasedev->fd = ret;
>> +    vbasedev->group = group;
>> +    QLIST_INSERT_HEAD(&group->device_list, vbasedev, next);
>>  
>> -    ret = ioctl(vdev->vbasedev.fd, VFIO_DEVICE_GET_IRQ_INFO, &irq_info);
>> +    ret = ioctl(vbasedev->fd, VFIO_DEVICE_GET_INFO, &dev_info);
>>      if (ret) {
>> -        /* This can fail for an old kernel or legacy PCI dev */
>> -        DPRINTF("VFIO_DEVICE_GET_IRQ_INFO failure: %m\n");
>> -        ret = 0;
>> -    } else if (irq_info.count == 1) {
>> -        vdev->pci_aer = true;
>> -    } else {
>> -        error_report("vfio: %04x:%02x:%02x.%x "
>> -                     "Could not enable error recovery for the device",
>> -                     vdev->host.domain, vdev->host.bus, vdev->host.slot,
>> -                     vdev->host.function);
>> +        error_report("vfio: error getting device info: %m");
>> +        goto error;
>> +    }
>> +
>> +    vbasedev->num_irqs = dev_info.num_irqs;
>> +    vbasedev->num_regions = dev_info.num_regions;
>> +    vbasedev->flags = dev_info.flags;
>> +
>> +    DPRINTF("Device %s flags: %u, regions: %u, irgs: %u\n", name,
>> +            dev_info.flags, dev_info.num_regions, dev_info.num_irqs);
>> +
>> +    vbasedev->reset_works = !!(dev_info.flags & VFIO_DEVICE_FLAGS_RESET);
>> +
>> +    /* call device specific functions */
>> +    ret = vbasedev->ops->vfio_check_device(vbasedev);
>> +    if (ret) {
>> +        error_report("vfio: error when checking device %s\n",
>> +                     vbasedev->name);
>> +        goto error;
>> +    }
>> +    ret = vbasedev->ops->vfio_populate_regions(vbasedev);
>> +    if (ret) {
>> +        error_report("vfio: error when populating regions of device %s\n",
>> +                     vbasedev->name);
>> +        goto error;
>> +    }
>> +    ret = vbasedev->ops->vfio_populate_interrupts(vbasedev);
>> +    if (ret) {
>> +        error_report("vfio: error when populating interrupts of device 
>> %s\n",
>> +                     vbasedev->name);
>> +        goto error;
>>      }
>>  
>>  error:
>>      if (ret) {
>> -        QLIST_REMOVE(&vdev->vbasedev, next);
>> -        vdev->vbasedev.group = NULL;
>> -        close(vdev->vbasedev.fd);
>> +        vfio_put_base_device(vbasedev);
> 
> Whoops, more confusion, the call-out functions are doing put calls
> (well, some of them) and so is this.  This is the only place it should
> occur.
OK
> 
>>      }
>>      return ret;
>>  }
>>  
>> -static void vfio_put_device(VFIOPCIDevice *vdev)
>> +void vfio_put_base_device(VFIODevice *vbasedev)
>>  {
>> -    QLIST_REMOVE(&vdev->vbasedev, next);
>> -    vdev->vbasedev.group = NULL;
>> +    QLIST_REMOVE(vbasedev, next);
>> +    vbasedev->group = NULL;
>>      DPRINTF("vfio_put_device: close vdev->fd\n");
>> -    close(vdev->vbasedev.fd);
>> -    g_free(vdev->vbasedev.name);
>> +    close(vbasedev->fd);
>> +    g_free(vbasedev->name);
> 
> get/put of the base device is still a bit messy.  .name doesn't get
> allocated by the get, but gets freed by the put.

.name dealloc moved to vfio_put_device

Thank you for your review

Best Regards

Eric
> 
>> +}
>> +
>> +static void vfio_put_device(VFIOPCIDevice *vdev)
>> +{
>> +    vfio_put_base_device(&vdev->vbasedev);
>>      if (vdev->msix) {
>>          g_free(vdev->msix);
>>          vdev->msix = NULL;
>> @@ -4266,7 +4327,7 @@ static int vfio_initfn(PCIDevice *pdev)
>>          }
>>      }
>>  
>> -    ret = vfio_get_device(group, path, vdev);
>> +    ret = vfio_get_device(group, path, &vdev->vbasedev);
>>      if (ret) {
>>          error_report("vfio: failed to get device %s", path);
>>          vfio_put_group(group);
> 
> 
>