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Date: Wed, 13 Dec 2017 14:34:59 +0530
From: Kirti Wankhede <kwankhede@...dia.com>
To: Zhenyu Wang <zhenyuw@...ux.intel.com>,
Alexey Kardashevskiy <aik@...abs.ru>
CC: Alex Williamson <alex.williamson@...hat.com>,
<linux-kernel@...r.kernel.org>, <kvm@...r.kernel.org>,
<intel-gvt-dev@...ts.freedesktop.org>, <zhi.a.wang@...el.com>
Subject: Re: [PATCH] vfio: Simplify capability helper
On 12/13/2017 12:31 PM, Zhenyu Wang wrote:
> On 2017.12.13 12:13:34 +1100, Alexey Kardashevskiy wrote:
>> On 13/12/17 06:59, Alex Williamson wrote:
>>> The vfio_info_add_capability() helper requires the caller to pass a
>>> capability ID, which it then uses to fill in header fields, assuming
>>> hard coded versions. This makes for an awkward and rigid interface.
>>> The only thing we want this helper to do is allocate sufficient
>>> space in the caps buffer and chain this capability into the list.
>>> Reduce it to that simple task.
>>>
>>> Signed-off-by: Alex Williamson <alex.williamson@...hat.com>
>>
>>
>> Makes more sense now, thanks. I'll repost mine on top of this.
>>
>>
>> Reviewed-by: Alexey Kardashevskiy <aik@...abs.ru>
>>
>>
>
> Looks good for KVMGT part.
>
> Acked-by: Zhenyu Wang <zhenyuw@...ux.intel.com>
>
Looks good to me too.
Reviewed-by: Kirti Wankhede <kwankhede@...dia.com>
Thanks,
Kirti
>> Below one observation, unrelated to this patch.
>>
>>> ---
>>> drivers/gpu/drm/i915/gvt/kvmgt.c | 15 +++++++----
>>> drivers/vfio/pci/vfio_pci.c | 14 ++++++----
>>> drivers/vfio/vfio.c | 52 +++-----------------------------------
>>> include/linux/vfio.h | 3 +-
>>> 4 files changed, 24 insertions(+), 60 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/i915/gvt/kvmgt.c b/drivers/gpu/drm/i915/gvt/kvmgt.c
>>> index 96060920a6fe..0a7d084da1a2 100644
>>> --- a/drivers/gpu/drm/i915/gvt/kvmgt.c
>>> +++ b/drivers/gpu/drm/i915/gvt/kvmgt.c
>>> @@ -1012,6 +1012,8 @@ static long intel_vgpu_ioctl(struct mdev_device *mdev, unsigned int cmd,
>>> if (!sparse)
>>> return -ENOMEM;
>>>
>>> + sparse->header.id = VFIO_REGION_INFO_CAP_SPARSE_MMAP;
>>> + sparse->header.version = 1;
>>> sparse->nr_areas = nr_areas;
>>> cap_type_id = VFIO_REGION_INFO_CAP_SPARSE_MMAP;
>>
>>
>> @cap_type_id is initialized in just one of many cases of switch
>> (info.index) and after the entire switch, there is switch (cap_type_id). I
>> wonder why compiler missed "potentially uninitialized variable here,
>> although there is no bug - @cap_type_id is in sync with @spapse. It would
>> make it cleaner imho just to have vfio_info_add_capability() next to the
>> header initialization.
>>
>
> yeah, we could clean that up, thanks for pointing out.
>
>>
>>
>>> sparse->areas[0].offset =
>>> @@ -1033,7 +1035,9 @@ static long intel_vgpu_ioctl(struct mdev_device *mdev, unsigned int cmd,
>>> break;
>>> default:
>>> {
>>> - struct vfio_region_info_cap_type cap_type;
>>> + struct vfio_region_info_cap_type cap_type = {
>>> + .header.id = VFIO_REGION_INFO_CAP_TYPE,
>>> + .header.version = 1 };
>>>
>>> if (info.index >= VFIO_PCI_NUM_REGIONS +
>>> vgpu->vdev.num_regions)
>>> @@ -1050,8 +1054,8 @@ static long intel_vgpu_ioctl(struct mdev_device *mdev, unsigned int cmd,
>>> cap_type.subtype = vgpu->vdev.region[i].subtype;
>>>
>>> ret = vfio_info_add_capability(&caps,
>>> - VFIO_REGION_INFO_CAP_TYPE,
>>> - &cap_type);
>>> + &cap_type.header,
>>> + sizeof(cap_type));
>>> if (ret)
>>> return ret;
>>> }
>>> @@ -1061,8 +1065,9 @@ static long intel_vgpu_ioctl(struct mdev_device *mdev, unsigned int cmd,
>>> switch (cap_type_id) {
>>> case VFIO_REGION_INFO_CAP_SPARSE_MMAP:
>>> ret = vfio_info_add_capability(&caps,
>>> - VFIO_REGION_INFO_CAP_SPARSE_MMAP,
>>> - sparse);
>>> + &sparse->header, sizeof(*sparse) +
>>> + (sparse->nr_areas *
>>> + sizeof(*sparse->areas)));
>>> kfree(sparse);
>>> if (ret)
>>> return ret;
>>> diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
>>> index f041b1a6cf66..a73e40983880 100644
>>> --- a/drivers/vfio/pci/vfio_pci.c
>>> +++ b/drivers/vfio/pci/vfio_pci.c
>>> @@ -582,6 +582,8 @@ static int msix_sparse_mmap_cap(struct vfio_pci_device *vdev,
>>> if (!sparse)
>>> return -ENOMEM;
>>>
>>> + sparse->header.id = VFIO_REGION_INFO_CAP_SPARSE_MMAP;
>>> + sparse->header.version = 1;
>>> sparse->nr_areas = nr_areas;
>>>
>>> if (vdev->msix_offset & PAGE_MASK) {
>>> @@ -597,8 +599,7 @@ static int msix_sparse_mmap_cap(struct vfio_pci_device *vdev,
>>> i++;
>>> }
>>>
>>> - ret = vfio_info_add_capability(caps, VFIO_REGION_INFO_CAP_SPARSE_MMAP,
>>> - sparse);
>>> + ret = vfio_info_add_capability(caps, &sparse->header, size);
>>> kfree(sparse);
>>>
>>> return ret;
>>> @@ -741,7 +742,9 @@ static long vfio_pci_ioctl(void *device_data,
>>> break;
>>> default:
>>> {
>>> - struct vfio_region_info_cap_type cap_type;
>>> + struct vfio_region_info_cap_type cap_type = {
>>> + .header.id = VFIO_REGION_INFO_CAP_TYPE,
>>> + .header.version = 1 };
>>>
>>> if (info.index >=
>>> VFIO_PCI_NUM_REGIONS + vdev->num_regions)
>>> @@ -756,9 +759,8 @@ static long vfio_pci_ioctl(void *device_data,
>>> cap_type.type = vdev->region[i].type;
>>> cap_type.subtype = vdev->region[i].subtype;
>>>
>>> - ret = vfio_info_add_capability(&caps,
>>> - VFIO_REGION_INFO_CAP_TYPE,
>>> - &cap_type);
>>> + ret = vfio_info_add_capability(&caps, &cap_type.header,
>>> + sizeof(cap_type));
>>> if (ret)
>>> return ret;
>>>
>>> diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
>>> index 2bc3705a99bd..721f97f8dac1 100644
>>> --- a/drivers/vfio/vfio.c
>>> +++ b/drivers/vfio/vfio.c
>>> @@ -1857,63 +1857,19 @@ void vfio_info_cap_shift(struct vfio_info_cap *caps, size_t offset)
>>> }
>>> EXPORT_SYMBOL(vfio_info_cap_shift);
>>>
>>> -static int sparse_mmap_cap(struct vfio_info_cap *caps, void *cap_type)
>>> +int vfio_info_add_capability(struct vfio_info_cap *caps,
>>> + struct vfio_info_cap_header *cap, size_t size)
>>> {
>>> struct vfio_info_cap_header *header;
>>> - struct vfio_region_info_cap_sparse_mmap *sparse_cap, *sparse = cap_type;
>>> - size_t size;
>>>
>>> - size = sizeof(*sparse) + sparse->nr_areas * sizeof(*sparse->areas);
>>> - header = vfio_info_cap_add(caps, size,
>>> - VFIO_REGION_INFO_CAP_SPARSE_MMAP, 1);
>>> + header = vfio_info_cap_add(caps, size, cap->id, cap->version);
>>> if (IS_ERR(header))
>>> return PTR_ERR(header);
>>>
>>> - sparse_cap = container_of(header,
>>> - struct vfio_region_info_cap_sparse_mmap, header);
>>> - sparse_cap->nr_areas = sparse->nr_areas;
>>> - memcpy(sparse_cap->areas, sparse->areas,
>>> - sparse->nr_areas * sizeof(*sparse->areas));
>>> - return 0;
>>> -}
>>> -
>>> -static int region_type_cap(struct vfio_info_cap *caps, void *cap_type)
>>> -{
>>> - struct vfio_info_cap_header *header;
>>> - struct vfio_region_info_cap_type *type_cap, *cap = cap_type;
>>> + memcpy(header + 1, cap + 1, size - sizeof(*header));
>>>
>>> - header = vfio_info_cap_add(caps, sizeof(*cap),
>>> - VFIO_REGION_INFO_CAP_TYPE, 1);
>>> - if (IS_ERR(header))
>>> - return PTR_ERR(header);
>>> -
>>> - type_cap = container_of(header, struct vfio_region_info_cap_type,
>>> - header);
>>> - type_cap->type = cap->type;
>>> - type_cap->subtype = cap->subtype;
>>> return 0;
>>> }
>>> -
>>> -int vfio_info_add_capability(struct vfio_info_cap *caps, int cap_type_id,
>>> - void *cap_type)
>>> -{
>>> - int ret = -EINVAL;
>>> -
>>> - if (!cap_type)
>>> - return 0;
>>> -
>>> - switch (cap_type_id) {
>>> - case VFIO_REGION_INFO_CAP_SPARSE_MMAP:
>>> - ret = sparse_mmap_cap(caps, cap_type);
>>> - break;
>>> -
>>> - case VFIO_REGION_INFO_CAP_TYPE:
>>> - ret = region_type_cap(caps, cap_type);
>>> - break;
>>> - }
>>> -
>>> - return ret;
>>> -}
>>> EXPORT_SYMBOL(vfio_info_add_capability);
>>>
>>> int vfio_set_irqs_validate_and_prepare(struct vfio_irq_set *hdr, int num_irqs,
>>> diff --git a/include/linux/vfio.h b/include/linux/vfio.h
>>> index a47b985341d1..66741ab087c1 100644
>>> --- a/include/linux/vfio.h
>>> +++ b/include/linux/vfio.h
>>> @@ -145,7 +145,8 @@ extern struct vfio_info_cap_header *vfio_info_cap_add(
>>> 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);
>>> + struct vfio_info_cap_header *cap,
>>> + size_t size);
>>>
>>> extern int vfio_set_irqs_validate_and_prepare(struct vfio_irq_set *hdr,
>>> int num_irqs, int max_irq_type,
>>>
>>
>>
>> --
>> Alexey
>
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