Re: [PATCH v11 15/22] vfio: Introduce vfio_set_irqs_validate_and_prepare()

From: Alexey Kardashevskiy
Date: Tue Nov 08 2016 - 03:46:45 EST


On 05/11/16 08:10, Kirti Wankhede wrote:
> Vendor driver using mediated device framework would use same mechnism to
> validate and prepare IRQs. Introducing this function to reduce code
> replication in multiple drivers.
>
> Signed-off-by: Kirti Wankhede <kwankhede@xxxxxxxxxx>
> Signed-off-by: Neo Jia <cjia@xxxxxxxxxx>
> Change-Id: Ie201f269dda0713ca18a07dc4852500bd8b48309
> ---
> drivers/vfio/vfio.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
> include/linux/vfio.h | 4 ++++
> 2 files changed, 52 insertions(+)
>
> diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
> index 9a03be0942a1..ed2361e4b904 100644
> --- a/drivers/vfio/vfio.c
> +++ b/drivers/vfio/vfio.c
> @@ -1858,6 +1858,54 @@ int vfio_info_add_capability(struct vfio_info_cap *caps, int cap_type_id,
> }
> EXPORT_SYMBOL(vfio_info_add_capability);
>
> +int vfio_set_irqs_validate_and_prepare(struct vfio_irq_set *hdr, int num_irqs,
> + int max_irq_type, size_t *data_size)
> +{
> + unsigned long minsz;
> + size_t size;
> +
> + minsz = offsetofend(struct vfio_irq_set, count);
> +
> + if ((hdr->argsz < minsz) || (hdr->index >= max_irq_type) ||
> + (hdr->count >= (U32_MAX - hdr->start)) ||
> + (hdr->flags & ~(VFIO_IRQ_SET_DATA_TYPE_MASK |
> + VFIO_IRQ_SET_ACTION_TYPE_MASK)))
> + return -EINVAL;
> +
> + if (data_size)

Pointless check, the callers will pass non null pointer with value
initialized to 0 anyway.


> + *data_size = 0;
> +
> + if (hdr->start >= num_irqs || hdr->start + hdr->count > num_irqs)
> + return -EINVAL;
> +
> + switch (hdr->flags & VFIO_IRQ_SET_DATA_TYPE_MASK) {
> + case VFIO_IRQ_SET_DATA_NONE:
> + size = 0;
> + break;
> + case VFIO_IRQ_SET_DATA_BOOL:
> + size = sizeof(uint8_t);
> + break;
> + case VFIO_IRQ_SET_DATA_EVENTFD:
> + size = sizeof(int32_t);
> + break;
> + default:
> + return -EINVAL;
> + }
> +
> + if (size) {

The whole branch would even work for size == 0.

> + if (hdr->argsz - minsz < hdr->count * size)
> + return -EINVAL;
> +
> + if (!data_size)
> + return -EINVAL;

Redundant check as well.

> +
> + *data_size = hdr->count * size;
> + }
> +
> + return 0;
> +}

It does not really prepare anything as the name suggests. It looks like
this is 2 different helpers actually:

int vfio_set_irqs_validate()
and
size_t vfio_set_irqs_hdr_to_data_size()


And it would make it easier to review/bisect if 16/22 and 17/22 were merged
into this one as this patch alone adds new code which it does not use and
all 3 patches are fairly small.


> +EXPORT_SYMBOL(vfio_set_irqs_validate_and_prepare);

Everything you export in this patchset is EXPORT_SYMBOL() while the
existing code uses EXPORT_SYMBOL_GPL(), is this for a reason?


> +
> /*
> * Pin a set of guest PFNs and return their associated host PFNs for local
> * domain only.
> diff --git a/include/linux/vfio.h b/include/linux/vfio.h
> index cf90393a11e2..87c9afecd822 100644
> --- a/include/linux/vfio.h
> +++ b/include/linux/vfio.h
> @@ -116,6 +116,10 @@ extern void vfio_info_cap_shift(struct vfio_info_cap *caps, size_t offset);
> extern int vfio_info_add_capability(struct vfio_info_cap *caps,
> int cap_type_id, void *cap_type);
>
> +extern int vfio_set_irqs_validate_and_prepare(struct vfio_irq_set *hdr,
> + int num_irqs, int max_irq_type,
> + size_t *data_size);
> +
> struct pci_dev;
> #ifdef CONFIG_EEH
> extern void vfio_spapr_pci_eeh_open(struct pci_dev *pdev);
>


--
Alexey