Re: [PATCH V4 vfio 8/9] vfio/pci: Expose vfio_pci_iowrite/read##size()

[Yishai Hadas <yishaih@xxxxxxxxxx>]

On 30/11/2023 21:20, Alex Williamson wrote:
> On Wed, 29 Nov 2023 16:37:45 +0200
> Yishai Hadas <yishaih@xxxxxxxxxx> wrote:
>
> > Expose vfio_pci_iowrite/read##size() to let it be used by drivers.
> >
> > This functionality is needed to enable direct access to some physical
> > BAR of the device with the proper locks/checks in place.
> >
> > The next patches from this series will use this functionality on a data
> > path flow when a direct access to the BAR is needed.
> >
> > Signed-off-by: Yishai Hadas <yishaih@xxxxxxxxxx>
> > ---
> >   drivers/vfio/pci/vfio_pci_rdwr.c | 10 ++++++----
> >   include/linux/vfio_pci_core.h    | 19 +++++++++++++++++++
> >   2 files changed, 25 insertions(+), 4 deletions(-)
>
> I don't follow the inconsistency between this and the previous patch.
> Why did we move and rename the code to setup the barmap but we export
> the ioread/write functions in place?  Thanks,
>
> Alex

The mount of code for barmap setup was quite small compared to the 
ioread/write functions.

However, I agree, we can be consistent here and export in both cases the 
functions in place as part of vfio_pci_rdwr.c which is already part of 
vfio_pci_core.ko

I may also rename in current patch vfio_pci_iowrite/read<xxx> to have 
the 'core' prefix as part of the functions names (i.e. 
vfio_pci_core_iowrite/read<xxx>) to be consistent with other exported 
core functions and adapt the callers to this name.

Makes sense ?

Yishai

> > diff --git a/drivers/vfio/pci/vfio_pci_rdwr.c b/drivers/vfio/pci/vfio_pci_rdwr.c
> > index 6f08b3ecbb89..817ec9a89123 100644
> > --- a/drivers/vfio/pci/vfio_pci_rdwr.c
> > +++ b/drivers/vfio/pci/vfio_pci_rdwr.c
> > @@ -38,7 +38,7 @@
> >   #define vfio_iowrite8	iowrite8
> >   
> >   #define VFIO_IOWRITE(size) \
> > -static int vfio_pci_iowrite##size(struct vfio_pci_core_device *vdev,		\
> > +int vfio_pci_iowrite##size(struct vfio_pci_core_device *vdev,		\
> >   			bool test_mem, u##size val, void __iomem *io)	\
> >   {									\
> >   	if (test_mem) {							\
> > @@ -55,7 +55,8 @@ static int vfio_pci_iowrite##size(struct vfio_pci_core_device *vdev,		\
> >   		up_read(&vdev->memory_lock);				\
> >   									\
> >   	return 0;							\
> > -}
> > +}									\
> > +EXPORT_SYMBOL_GPL(vfio_pci_iowrite##size);
> >   
> >   VFIO_IOWRITE(8)
> >   VFIO_IOWRITE(16)
> > @@ -65,7 +66,7 @@ VFIO_IOWRITE(64)
> >   #endif
> >   
> >   #define VFIO_IOREAD(size) \
> > -static int vfio_pci_ioread##size(struct vfio_pci_core_device *vdev,		\
> > +int vfio_pci_ioread##size(struct vfio_pci_core_device *vdev,		\
> >   			bool test_mem, u##size *val, void __iomem *io)	\
> >   {									\
> >   	if (test_mem) {							\
> > @@ -82,7 +83,8 @@ static int vfio_pci_ioread##size(struct vfio_pci_core_device *vdev,		\
> >   		up_read(&vdev->memory_lock);				\
> >   									\
> >   	return 0;							\
> > -}
> > +}									\
> > +EXPORT_SYMBOL_GPL(vfio_pci_ioread##size);
> >   
> >   VFIO_IOREAD(8)
> >   VFIO_IOREAD(16)
> > diff --git a/include/linux/vfio_pci_core.h b/include/linux/vfio_pci_core.h
> > index 67ac58e20e1d..22c915317788 100644
> > --- a/include/linux/vfio_pci_core.h
> > +++ b/include/linux/vfio_pci_core.h
> > @@ -131,4 +131,23 @@ int vfio_pci_core_setup_barmap(struct vfio_pci_core_device *vdev, int bar);
> >   pci_ers_result_t vfio_pci_core_aer_err_detected(struct pci_dev *pdev,
> >   						pci_channel_state_t state);
> >   
> > +#define VFIO_IOWRITE_DECLATION(size) \
> > +int vfio_pci_iowrite##size(struct vfio_pci_core_device *vdev,		\
> > +			bool test_mem, u##size val, void __iomem *io);
> > +
> > +VFIO_IOWRITE_DECLATION(8)
> > +VFIO_IOWRITE_DECLATION(16)
> > +VFIO_IOWRITE_DECLATION(32)
> > +#ifdef iowrite64
> > +VFIO_IOWRITE_DECLATION(64)
> > +#endif
> > +
> > +#define VFIO_IOREAD_DECLATION(size) \
> > +int vfio_pci_ioread##size(struct vfio_pci_core_device *vdev,		\
> > +			bool test_mem, u##size *val, void __iomem *io);
> > +
> > +VFIO_IOREAD_DECLATION(8)
> > +VFIO_IOREAD_DECLATION(16)
> > +VFIO_IOREAD_DECLATION(32)
> > +
> >   #endif /* VFIO_PCI_CORE_H */