2018-01-06 19:30:44

by Alexander Kapshuk

[permalink] [raw]
Subject: [PATCH] vboxvideo: Fix incorrect type in assignment sparse warning

On Sat, Jan 6, 2018 at 6:00 PM, Hans de Goede <[email protected]> wrote:
> Hi,
>
>
> On 06-01-18 15:20, Alexander Kapshuk wrote:
>>
>> On Mon, Dec 25, 2017 at 04:42:59PM +0200, Alexander Kapshuk wrote:
>>>
>>> Sparse emitted the following warning:
>>> ../drivers/staging/vboxvideo/vbox_fb.c:173:27: warning: incorrect type in
>>> assignment (different address spaces)
>>> ../drivers/staging/vboxvideo/vbox_fb.c:173:27: expected char [noderef]
>>> <asn:2>*screen_base
>>> ../drivers/staging/vboxvideo/vbox_fb.c:173:27: got void *virtual
>>>
>>> The vbox_bo buffer object kernel mapping is handled by a call
>>> to ttm_bo_kmap() prior to the assignment of bo->kmap.virtual to
>>> info->screen_base of type char __iomem*.
>>> Casting bo->kmap.virtual to char __iomem* in this assignment fixes
>>> the warning.
>>>
>>> vboxvideo: Fix address space of expression removal sparse warning
>>>
>>> Sparse emitted the following warning:
>>> ../drivers/staging/vboxvideo/vbox_main.c:64:25: warning: cast removes
>>> address space of expression
>>>
>>> vbox->vbva_buffers iomapping is handled by calling vbox_accel_init()
>>> from vbox_hw_init().
>>> __force attribute is used in assignment to vbva to fix the warning.
>>>
>>> Signed-off-by: Alexander Kapshuk <[email protected]>
>>> ---
>>> drivers/staging/vboxvideo/vbox_fb.c | 2 +-
>>> drivers/staging/vboxvideo/vbox_main.c | 2 +-
>>> 2 files changed, 2 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/staging/vboxvideo/vbox_fb.c
>>> b/drivers/staging/vboxvideo/vbox_fb.c
>>> index 8aed248db6e2..43c39eca4ae1 100644
>>> --- a/drivers/staging/vboxvideo/vbox_fb.c
>>> +++ b/drivers/staging/vboxvideo/vbox_fb.c
>>> @@ -170,7 +170,7 @@ static int vboxfb_create(struct drm_fb_helper
>>> *helper,
>>> drm_fb_helper_fill_var(info, &fbdev->helper, sizes->fb_width,
>>> sizes->fb_height);
>>>
>>> - info->screen_base = bo->kmap.virtual;
>>> + info->screen_base = (char __iomem *)bo->kmap.virtual;
>>> info->screen_size = size;
>>>
>>> #ifdef CONFIG_DRM_KMS_FB_HELPER
>
>
> This fix looks good to me.
>
>>> diff --git a/drivers/staging/vboxvideo/vbox_main.c
>>> b/drivers/staging/vboxvideo/vbox_main.c
>>> index 80bd039fa08e..973b3bcc04b1 100644
>>> --- a/drivers/staging/vboxvideo/vbox_main.c
>>> +++ b/drivers/staging/vboxvideo/vbox_main.c
>>> @@ -61,7 +61,7 @@ void vbox_enable_accel(struct vbox_private *vbox)
>>> if (vbox->vbva_info[i].vbva)
>>> continue;
>>>
>>> - vbva = (void *)vbox->vbva_buffers + i *
>>> VBVA_MIN_BUFFER_SIZE;
>>> + vbva = (void __force *)vbox->vbva_buffers + i *
>>> VBVA_MIN_BUFFER_SIZE;
>>> if (!vbva_enable(&vbox->vbva_info[i],
>>> vbox->guest_pool, vbva, i)) {
>>> /* very old host or driver error. */
>
>
> Hmm, isn't there a cleaner way to fix this ? Maybe make vbva_enable's
> argument (and the local vbva variable) of type u8 __iomem * too ?
>
> Regards,
>
> Hans

Hi Hans,

Thanks for your prompt response.

I had a good look at the vbva_enable() function's definition and to
the best of my knowledge, changing vbva's type from 'struct
vbva_buffer *' to 'u8 __iomem *' wouldn't work.
vbva_enable() relies on vbva's type being a pointer to 'struct vbva_buffer':
vbva's memory gets set to zero;
some of vbva's members are initialised to particular values;
vbva_ctx->vbva expects vbva to be a pointer to 'struct vbva_buffer' as well;

Or am I misreading this?
What are your thoughts on this?
Thanks.

Alexander.


2018-01-06 19:44:03

by Hans de Goede

[permalink] [raw]
Subject: Re: [PATCH] vboxvideo: Fix incorrect type in assignment sparse warning

HI,

On 06-01-18 20:30, Alexander Kapshuk wrote:
> On Sat, Jan 6, 2018 at 6:00 PM, Hans de Goede <[email protected]> wrote:
>> Hi,
>>
>>
>> On 06-01-18 15:20, Alexander Kapshuk wrote:
>>>
>>> On Mon, Dec 25, 2017 at 04:42:59PM +0200, Alexander Kapshuk wrote:
>>>>
>>>> Sparse emitted the following warning:
>>>> ../drivers/staging/vboxvideo/vbox_fb.c:173:27: warning: incorrect type in
>>>> assignment (different address spaces)
>>>> ../drivers/staging/vboxvideo/vbox_fb.c:173:27: expected char [noderef]
>>>> <asn:2>*screen_base
>>>> ../drivers/staging/vboxvideo/vbox_fb.c:173:27: got void *virtual
>>>>
>>>> The vbox_bo buffer object kernel mapping is handled by a call
>>>> to ttm_bo_kmap() prior to the assignment of bo->kmap.virtual to
>>>> info->screen_base of type char __iomem*.
>>>> Casting bo->kmap.virtual to char __iomem* in this assignment fixes
>>>> the warning.
>>>>
>>>> vboxvideo: Fix address space of expression removal sparse warning
>>>>
>>>> Sparse emitted the following warning:
>>>> ../drivers/staging/vboxvideo/vbox_main.c:64:25: warning: cast removes
>>>> address space of expression
>>>>
>>>> vbox->vbva_buffers iomapping is handled by calling vbox_accel_init()
>>>> from vbox_hw_init().
>>>> __force attribute is used in assignment to vbva to fix the warning.
>>>>
>>>> Signed-off-by: Alexander Kapshuk <[email protected]>
>>>> ---
>>>> drivers/staging/vboxvideo/vbox_fb.c | 2 +-
>>>> drivers/staging/vboxvideo/vbox_main.c | 2 +-
>>>> 2 files changed, 2 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/drivers/staging/vboxvideo/vbox_fb.c
>>>> b/drivers/staging/vboxvideo/vbox_fb.c
>>>> index 8aed248db6e2..43c39eca4ae1 100644
>>>> --- a/drivers/staging/vboxvideo/vbox_fb.c
>>>> +++ b/drivers/staging/vboxvideo/vbox_fb.c
>>>> @@ -170,7 +170,7 @@ static int vboxfb_create(struct drm_fb_helper
>>>> *helper,
>>>> drm_fb_helper_fill_var(info, &fbdev->helper, sizes->fb_width,
>>>> sizes->fb_height);
>>>>
>>>> - info->screen_base = bo->kmap.virtual;
>>>> + info->screen_base = (char __iomem *)bo->kmap.virtual;
>>>> info->screen_size = size;
>>>>
>>>> #ifdef CONFIG_DRM_KMS_FB_HELPER
>>
>>
>> This fix looks good to me.
>>
>>>> diff --git a/drivers/staging/vboxvideo/vbox_main.c
>>>> b/drivers/staging/vboxvideo/vbox_main.c
>>>> index 80bd039fa08e..973b3bcc04b1 100644
>>>> --- a/drivers/staging/vboxvideo/vbox_main.c
>>>> +++ b/drivers/staging/vboxvideo/vbox_main.c
>>>> @@ -61,7 +61,7 @@ void vbox_enable_accel(struct vbox_private *vbox)
>>>> if (vbox->vbva_info[i].vbva)
>>>> continue;
>>>>
>>>> - vbva = (void *)vbox->vbva_buffers + i *
>>>> VBVA_MIN_BUFFER_SIZE;
>>>> + vbva = (void __force *)vbox->vbva_buffers + i *
>>>> VBVA_MIN_BUFFER_SIZE;
>>>> if (!vbva_enable(&vbox->vbva_info[i],
>>>> vbox->guest_pool, vbva, i)) {
>>>> /* very old host or driver error. */
>>
>>
>> Hmm, isn't there a cleaner way to fix this ? Maybe make vbva_enable's
>> argument (and the local vbva variable) of type u8 __iomem * too ?
>>
>> Regards,
>>
>> Hans
>
> Hi Hans,
>
> Thanks for your prompt response.
>
> I had a good look at the vbva_enable() function's definition and to
> the best of my knowledge, changing vbva's type from 'struct
> vbva_buffer *' to 'u8 __iomem *' wouldn't work.
> vbva_enable() relies on vbva's type being a pointer to 'struct vbva_buffer':
> vbva's memory gets set to zero;
> some of vbva's members are initialised to particular values;
> vbva_ctx->vbva expects vbva to be a pointer to 'struct vbva_buffer' as well;
>
> Or am I misreading this?

No your not misreading this I did not check the function myself before
commenting myself, my bad.

> What are your thoughts on this?

Lets just move ahead with your original fix:

Reviewed-by: Hans de Goede <[email protected]>

Regards,

Hans

2018-01-06 19:56:42

by Alexander Kapshuk

[permalink] [raw]
Subject: Re: [PATCH] vboxvideo: Fix incorrect type in assignment sparse warning

On Sat, Jan 6, 2018 at 9:43 PM, Hans de Goede <[email protected]> wrote:
> HI,
>
>
> On 06-01-18 20:30, Alexander Kapshuk wrote:
>>
>> On Sat, Jan 6, 2018 at 6:00 PM, Hans de Goede <[email protected]> wrote:
>>>
>>> Hi,
>>>
>>>
>>> On 06-01-18 15:20, Alexander Kapshuk wrote:
>>>>
>>>>
>>>> On Mon, Dec 25, 2017 at 04:42:59PM +0200, Alexander Kapshuk wrote:
>>>>>
>>>>>
>>>>> Sparse emitted the following warning:
>>>>> ../drivers/staging/vboxvideo/vbox_fb.c:173:27: warning: incorrect type
>>>>> in
>>>>> assignment (different address spaces)
>>>>> ../drivers/staging/vboxvideo/vbox_fb.c:173:27: expected char
>>>>> [noderef]
>>>>> <asn:2>*screen_base
>>>>> ../drivers/staging/vboxvideo/vbox_fb.c:173:27: got void *virtual
>>>>>
>>>>> The vbox_bo buffer object kernel mapping is handled by a call
>>>>> to ttm_bo_kmap() prior to the assignment of bo->kmap.virtual to
>>>>> info->screen_base of type char __iomem*.
>>>>> Casting bo->kmap.virtual to char __iomem* in this assignment fixes
>>>>> the warning.
>>>>>
>>>>> vboxvideo: Fix address space of expression removal sparse warning
>>>>>
>>>>> Sparse emitted the following warning:
>>>>> ../drivers/staging/vboxvideo/vbox_main.c:64:25: warning: cast removes
>>>>> address space of expression
>>>>>
>>>>> vbox->vbva_buffers iomapping is handled by calling vbox_accel_init()
>>>>> from vbox_hw_init().
>>>>> __force attribute is used in assignment to vbva to fix the warning.
>>>>>
>>>>> Signed-off-by: Alexander Kapshuk <[email protected]>
>>>>> ---
>>>>> drivers/staging/vboxvideo/vbox_fb.c | 2 +-
>>>>> drivers/staging/vboxvideo/vbox_main.c | 2 +-
>>>>> 2 files changed, 2 insertions(+), 2 deletions(-)
>>>>>
>>>>> diff --git a/drivers/staging/vboxvideo/vbox_fb.c
>>>>> b/drivers/staging/vboxvideo/vbox_fb.c
>>>>> index 8aed248db6e2..43c39eca4ae1 100644
>>>>> --- a/drivers/staging/vboxvideo/vbox_fb.c
>>>>> +++ b/drivers/staging/vboxvideo/vbox_fb.c
>>>>> @@ -170,7 +170,7 @@ static int vboxfb_create(struct drm_fb_helper
>>>>> *helper,
>>>>> drm_fb_helper_fill_var(info, &fbdev->helper, sizes->fb_width,
>>>>> sizes->fb_height);
>>>>>
>>>>> - info->screen_base = bo->kmap.virtual;
>>>>> + info->screen_base = (char __iomem *)bo->kmap.virtual;
>>>>> info->screen_size = size;
>>>>>
>>>>> #ifdef CONFIG_DRM_KMS_FB_HELPER
>>>
>>>
>>>
>>> This fix looks good to me.
>>>
>>>>> diff --git a/drivers/staging/vboxvideo/vbox_main.c
>>>>> b/drivers/staging/vboxvideo/vbox_main.c
>>>>> index 80bd039fa08e..973b3bcc04b1 100644
>>>>> --- a/drivers/staging/vboxvideo/vbox_main.c
>>>>> +++ b/drivers/staging/vboxvideo/vbox_main.c
>>>>> @@ -61,7 +61,7 @@ void vbox_enable_accel(struct vbox_private *vbox)
>>>>> if (vbox->vbva_info[i].vbva)
>>>>> continue;
>>>>>
>>>>> - vbva = (void *)vbox->vbva_buffers + i *
>>>>> VBVA_MIN_BUFFER_SIZE;
>>>>> + vbva = (void __force *)vbox->vbva_buffers + i *
>>>>> VBVA_MIN_BUFFER_SIZE;
>>>>> if (!vbva_enable(&vbox->vbva_info[i],
>>>>> vbox->guest_pool, vbva, i)) {
>>>>> /* very old host or driver error. */
>>>
>>>
>>>
>>> Hmm, isn't there a cleaner way to fix this ? Maybe make vbva_enable's
>>> argument (and the local vbva variable) of type u8 __iomem * too ?
>>>
>>> Regards,
>>>
>>> Hans
>>
>>
>> Hi Hans,
>>
>> Thanks for your prompt response.
>>
>> I had a good look at the vbva_enable() function's definition and to
>> the best of my knowledge, changing vbva's type from 'struct
>> vbva_buffer *' to 'u8 __iomem *' wouldn't work.
>> vbva_enable() relies on vbva's type being a pointer to 'struct
>> vbva_buffer':
>> vbva's memory gets set to zero;
>> some of vbva's members are initialised to particular values;
>> vbva_ctx->vbva expects vbva to be a pointer to 'struct vbva_buffer' as
>> well;
>>
>> Or am I misreading this?
>
>
> No your not misreading this I did not check the function myself before
> commenting myself, my bad.

Thanks for confirming my understanding of this.

>
>> What are your thoughts on this?
>
>
> Lets just move ahead with your original fix:

Did you want me to resend the patch, or is someone going to pull the
original one I sent into their tree?
Thanks.

>
> Reviewed-by: Hans de Goede <[email protected]>
>
> Regards,
>
> Hans
>

2018-01-06 20:00:53

by Hans de Goede

[permalink] [raw]
Subject: Re: [PATCH] vboxvideo: Fix incorrect type in assignment sparse warning

Hi,

On 06-01-18 20:56, Alexander Kapshuk wrote:
> On Sat, Jan 6, 2018 at 9:43 PM, Hans de Goede <[email protected]> wrote:
>> HI,
>>
>>
>> On 06-01-18 20:30, Alexander Kapshuk wrote:
>>>
>>> On Sat, Jan 6, 2018 at 6:00 PM, Hans de Goede <[email protected]> wrote:
>>>>
>>>> Hi,
>>>>
>>>>
>>>> On 06-01-18 15:20, Alexander Kapshuk wrote:
>>>>>
>>>>>
>>>>> On Mon, Dec 25, 2017 at 04:42:59PM +0200, Alexander Kapshuk wrote:
>>>>>>
>>>>>>
>>>>>> Sparse emitted the following warning:
>>>>>> ../drivers/staging/vboxvideo/vbox_fb.c:173:27: warning: incorrect type
>>>>>> in
>>>>>> assignment (different address spaces)
>>>>>> ../drivers/staging/vboxvideo/vbox_fb.c:173:27: expected char
>>>>>> [noderef]
>>>>>> <asn:2>*screen_base
>>>>>> ../drivers/staging/vboxvideo/vbox_fb.c:173:27: got void *virtual
>>>>>>
>>>>>> The vbox_bo buffer object kernel mapping is handled by a call
>>>>>> to ttm_bo_kmap() prior to the assignment of bo->kmap.virtual to
>>>>>> info->screen_base of type char __iomem*.
>>>>>> Casting bo->kmap.virtual to char __iomem* in this assignment fixes
>>>>>> the warning.
>>>>>>
>>>>>> vboxvideo: Fix address space of expression removal sparse warning
>>>>>>
>>>>>> Sparse emitted the following warning:
>>>>>> ../drivers/staging/vboxvideo/vbox_main.c:64:25: warning: cast removes
>>>>>> address space of expression
>>>>>>
>>>>>> vbox->vbva_buffers iomapping is handled by calling vbox_accel_init()
>>>>>> from vbox_hw_init().
>>>>>> __force attribute is used in assignment to vbva to fix the warning.
>>>>>>
>>>>>> Signed-off-by: Alexander Kapshuk <[email protected]>
>>>>>> ---
>>>>>> drivers/staging/vboxvideo/vbox_fb.c | 2 +-
>>>>>> drivers/staging/vboxvideo/vbox_main.c | 2 +-
>>>>>> 2 files changed, 2 insertions(+), 2 deletions(-)
>>>>>>
>>>>>> diff --git a/drivers/staging/vboxvideo/vbox_fb.c
>>>>>> b/drivers/staging/vboxvideo/vbox_fb.c
>>>>>> index 8aed248db6e2..43c39eca4ae1 100644
>>>>>> --- a/drivers/staging/vboxvideo/vbox_fb.c
>>>>>> +++ b/drivers/staging/vboxvideo/vbox_fb.c
>>>>>> @@ -170,7 +170,7 @@ static int vboxfb_create(struct drm_fb_helper
>>>>>> *helper,
>>>>>> drm_fb_helper_fill_var(info, &fbdev->helper, sizes->fb_width,
>>>>>> sizes->fb_height);
>>>>>>
>>>>>> - info->screen_base = bo->kmap.virtual;
>>>>>> + info->screen_base = (char __iomem *)bo->kmap.virtual;
>>>>>> info->screen_size = size;
>>>>>>
>>>>>> #ifdef CONFIG_DRM_KMS_FB_HELPER
>>>>
>>>>
>>>>
>>>> This fix looks good to me.
>>>>
>>>>>> diff --git a/drivers/staging/vboxvideo/vbox_main.c
>>>>>> b/drivers/staging/vboxvideo/vbox_main.c
>>>>>> index 80bd039fa08e..973b3bcc04b1 100644
>>>>>> --- a/drivers/staging/vboxvideo/vbox_main.c
>>>>>> +++ b/drivers/staging/vboxvideo/vbox_main.c
>>>>>> @@ -61,7 +61,7 @@ void vbox_enable_accel(struct vbox_private *vbox)
>>>>>> if (vbox->vbva_info[i].vbva)
>>>>>> continue;
>>>>>>
>>>>>> - vbva = (void *)vbox->vbva_buffers + i *
>>>>>> VBVA_MIN_BUFFER_SIZE;
>>>>>> + vbva = (void __force *)vbox->vbva_buffers + i *
>>>>>> VBVA_MIN_BUFFER_SIZE;
>>>>>> if (!vbva_enable(&vbox->vbva_info[i],
>>>>>> vbox->guest_pool, vbva, i)) {
>>>>>> /* very old host or driver error. */
>>>>
>>>>
>>>>
>>>> Hmm, isn't there a cleaner way to fix this ? Maybe make vbva_enable's
>>>> argument (and the local vbva variable) of type u8 __iomem * too ?
>>>>
>>>> Regards,
>>>>
>>>> Hans
>>>
>>>
>>> Hi Hans,
>>>
>>> Thanks for your prompt response.
>>>
>>> I had a good look at the vbva_enable() function's definition and to
>>> the best of my knowledge, changing vbva's type from 'struct
>>> vbva_buffer *' to 'u8 __iomem *' wouldn't work.
>>> vbva_enable() relies on vbva's type being a pointer to 'struct
>>> vbva_buffer':
>>> vbva's memory gets set to zero;
>>> some of vbva's members are initialised to particular values;
>>> vbva_ctx->vbva expects vbva to be a pointer to 'struct vbva_buffer' as
>>> well;
>>>
>>> Or am I misreading this?
>>
>>
>> No your not misreading this I did not check the function myself before
>> commenting myself, my bad.
>
> Thanks for confirming my understanding of this.
>
>>
>>> What are your thoughts on this?
>>
>>
>> Lets just move ahead with your original fix:
>
> Did you want me to resend the patch, or is someone going to pull the
> original one I sent into their tree?
> Thanks.

I expect Greg to pick it up without a resend. But with all the Spectre
stuff going on right now he might miss it, so I would say give it 14 days
and if he has not picked it up by then, resend it with my reviewed-by
added.

Regards,

Hans

2018-01-06 20:03:14

by Alexander Kapshuk

[permalink] [raw]
Subject: Re: [PATCH] vboxvideo: Fix incorrect type in assignment sparse warning

On Sat, Jan 6, 2018 at 10:00 PM, Hans de Goede <[email protected]> wrote:
> Hi,
>
>
> On 06-01-18 20:56, Alexander Kapshuk wrote:
>>
>> On Sat, Jan 6, 2018 at 9:43 PM, Hans de Goede <[email protected]> wrote:
>>>
>>> HI,
>>>
>>>
>>> On 06-01-18 20:30, Alexander Kapshuk wrote:
>>>>
>>>>
>>>> On Sat, Jan 6, 2018 at 6:00 PM, Hans de Goede <[email protected]>
>>>> wrote:
>>>>>
>>>>>
>>>>> Hi,
>>>>>
>>>>>
>>>>> On 06-01-18 15:20, Alexander Kapshuk wrote:
>>>>>>
>>>>>>
>>>>>>
>>>>>> On Mon, Dec 25, 2017 at 04:42:59PM +0200, Alexander Kapshuk wrote:
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> Sparse emitted the following warning:
>>>>>>> ../drivers/staging/vboxvideo/vbox_fb.c:173:27: warning: incorrect
>>>>>>> type
>>>>>>> in
>>>>>>> assignment (different address spaces)
>>>>>>> ../drivers/staging/vboxvideo/vbox_fb.c:173:27: expected char
>>>>>>> [noderef]
>>>>>>> <asn:2>*screen_base
>>>>>>> ../drivers/staging/vboxvideo/vbox_fb.c:173:27: got void *virtual
>>>>>>>
>>>>>>> The vbox_bo buffer object kernel mapping is handled by a call
>>>>>>> to ttm_bo_kmap() prior to the assignment of bo->kmap.virtual to
>>>>>>> info->screen_base of type char __iomem*.
>>>>>>> Casting bo->kmap.virtual to char __iomem* in this assignment fixes
>>>>>>> the warning.
>>>>>>>
>>>>>>> vboxvideo: Fix address space of expression removal sparse warning
>>>>>>>
>>>>>>> Sparse emitted the following warning:
>>>>>>> ../drivers/staging/vboxvideo/vbox_main.c:64:25: warning: cast removes
>>>>>>> address space of expression
>>>>>>>
>>>>>>> vbox->vbva_buffers iomapping is handled by calling vbox_accel_init()
>>>>>>> from vbox_hw_init().
>>>>>>> __force attribute is used in assignment to vbva to fix the warning.
>>>>>>>
>>>>>>> Signed-off-by: Alexander Kapshuk <[email protected]>
>>>>>>> ---
>>>>>>> drivers/staging/vboxvideo/vbox_fb.c | 2 +-
>>>>>>> drivers/staging/vboxvideo/vbox_main.c | 2 +-
>>>>>>> 2 files changed, 2 insertions(+), 2 deletions(-)
>>>>>>>
>>>>>>> diff --git a/drivers/staging/vboxvideo/vbox_fb.c
>>>>>>> b/drivers/staging/vboxvideo/vbox_fb.c
>>>>>>> index 8aed248db6e2..43c39eca4ae1 100644
>>>>>>> --- a/drivers/staging/vboxvideo/vbox_fb.c
>>>>>>> +++ b/drivers/staging/vboxvideo/vbox_fb.c
>>>>>>> @@ -170,7 +170,7 @@ static int vboxfb_create(struct drm_fb_helper
>>>>>>> *helper,
>>>>>>> drm_fb_helper_fill_var(info, &fbdev->helper,
>>>>>>> sizes->fb_width,
>>>>>>> sizes->fb_height);
>>>>>>>
>>>>>>> - info->screen_base = bo->kmap.virtual;
>>>>>>> + info->screen_base = (char __iomem *)bo->kmap.virtual;
>>>>>>> info->screen_size = size;
>>>>>>>
>>>>>>> #ifdef CONFIG_DRM_KMS_FB_HELPER
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> This fix looks good to me.
>>>>>
>>>>>>> diff --git a/drivers/staging/vboxvideo/vbox_main.c
>>>>>>> b/drivers/staging/vboxvideo/vbox_main.c
>>>>>>> index 80bd039fa08e..973b3bcc04b1 100644
>>>>>>> --- a/drivers/staging/vboxvideo/vbox_main.c
>>>>>>> +++ b/drivers/staging/vboxvideo/vbox_main.c
>>>>>>> @@ -61,7 +61,7 @@ void vbox_enable_accel(struct vbox_private *vbox)
>>>>>>> if (vbox->vbva_info[i].vbva)
>>>>>>> continue;
>>>>>>>
>>>>>>> - vbva = (void *)vbox->vbva_buffers + i *
>>>>>>> VBVA_MIN_BUFFER_SIZE;
>>>>>>> + vbva = (void __force *)vbox->vbva_buffers + i *
>>>>>>> VBVA_MIN_BUFFER_SIZE;
>>>>>>> if (!vbva_enable(&vbox->vbva_info[i],
>>>>>>> vbox->guest_pool, vbva, i)) {
>>>>>>> /* very old host or driver error. */
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> Hmm, isn't there a cleaner way to fix this ? Maybe make vbva_enable's
>>>>> argument (and the local vbva variable) of type u8 __iomem * too ?
>>>>>
>>>>> Regards,
>>>>>
>>>>> Hans
>>>>
>>>>
>>>>
>>>> Hi Hans,
>>>>
>>>> Thanks for your prompt response.
>>>>
>>>> I had a good look at the vbva_enable() function's definition and to
>>>> the best of my knowledge, changing vbva's type from 'struct
>>>> vbva_buffer *' to 'u8 __iomem *' wouldn't work.
>>>> vbva_enable() relies on vbva's type being a pointer to 'struct
>>>> vbva_buffer':
>>>> vbva's memory gets set to zero;
>>>> some of vbva's members are initialised to particular values;
>>>> vbva_ctx->vbva expects vbva to be a pointer to 'struct vbva_buffer' as
>>>> well;
>>>>
>>>> Or am I misreading this?
>>>
>>>
>>>
>>> No your not misreading this I did not check the function myself before
>>> commenting myself, my bad.
>>
>>
>> Thanks for confirming my understanding of this.
>>
>>>
>>>> What are your thoughts on this?
>>>
>>>
>>>
>>> Lets just move ahead with your original fix:
>>
>>
>> Did you want me to resend the patch, or is someone going to pull the
>> original one I sent into their tree?
>> Thanks.
>
>
> I expect Greg to pick it up without a resend. But with all the Spectre
> stuff going on right now he might miss it, so I would say give it 14 days
> and if he has not picked it up by then, resend it with my reviewed-by
> added.
>
> Regards,
>
> Hans

Understood.
Thanks.