RE: [PATCH] vfio/qat: add PCI_IOV dependency

[Tian, Kevin]

> From: Zeng, Xin <xin.zeng@xxxxxxxxx>
> Sent: Wednesday, May 29, 2024 11:11 AM
> 
> On Wednesday, May 29, 2024 10:25 AM, Tian, Kevin <kevin.tian@xxxxxxxxx>
> > To: Arnd Bergmann <arnd@xxxxxxxxxx>; Zeng, Xin <xin.zeng@xxxxxxxxx>;
> > Cabiddu, Giovanni <giovanni.cabiddu@xxxxxxxxx>; Alex Williamson
> > <alex.williamson@xxxxxxxxxx>; Cao, Yahui <yahui.cao@xxxxxxxxx>
> > Cc: Arnd Bergmann <arnd@xxxxxxxx>; Jason Gunthorpe <jgg@xxxxxxxx>;
> > Yishai Hadas <yishaih@xxxxxxxxxx>; Shameer Kolothum
> > <shameerali.kolothum.thodi@xxxxxxxxxx>; kvm@xxxxxxxxxxxxxxx; qat-
> > linux <qat-linux@xxxxxxxxx>; linux-kernel@xxxxxxxxxxxxxxx
> > Subject: RE: [PATCH] vfio/qat: add PCI_IOV dependency
> >
> > > From: Arnd Bergmann <arnd@xxxxxxxxxx>
> > > Sent: Tuesday, May 28, 2024 8:05 PM
> > >
> > > From: Arnd Bergmann <arnd@xxxxxxxx>
> > >
> > > The newly added driver depends on the crypto driver, but it uses
> exported
> > > symbols that are only available when IOV is also turned on:
> > >
> > > x86_64-linux-ld: drivers/vfio/pci/qat/main.o: in function
> > > `qat_vf_pci_open_device':
> > > main.c:(.text+0xd7): undefined reference to `qat_vfmig_open'
> > > x86_64-linux-ld: drivers/vfio/pci/qat/main.o: in function
> > > `qat_vf_pci_release_dev':
> > > main.c:(.text+0x122): undefined reference to `qat_vfmig_cleanup'
> > > x86_64-linux-ld: main.c:(.text+0x12d): undefined reference to
> > > `qat_vfmig_destroy'
> > > x86_64-linux-ld: drivers/vfio/pci/qat/main.o: in function
> > > `qat_vf_resume_write':
> > > main.c:(.text+0x308): undefined reference to `qat_vfmig_load_setup'
> > > x86_64-linux-ld: drivers/vfio/pci/qat/main.o: in function
> > > `qat_vf_save_device_data':
> > > main.c:(.text+0x64c): undefined reference to `qat_vfmig_save_state'
> > > x86_64-linux-ld: main.c:(.text+0x677): undefined reference to
> > > `qat_vfmig_save_setup'
> > > x86_64-linux-ld: drivers/vfio/pci/qat/main.o: in function
> > > `qat_vf_pci_aer_reset_done':
> > > main.c:(.text+0x82d): undefined reference to `qat_vfmig_reset'
> > > x86_64-linux-ld: drivers/vfio/pci/qat/main.o: in function
> > > `qat_vf_pci_close_device':
> > > main.c:(.text+0x862): undefined reference to `qat_vfmig_close'
> > > x86_64-linux-ld: drivers/vfio/pci/qat/main.o: in function
> > > `qat_vf_pci_set_device_state':
> > > main.c:(.text+0x9af): undefined reference to `qat_vfmig_suspend'
> > > x86_64-linux-ld: main.c:(.text+0xa14): undefined reference to
> > > `qat_vfmig_save_state'
> > > x86_64-linux-ld: main.c:(.text+0xb37): undefined reference to
> > > `qat_vfmig_resume'
> > > x86_64-linux-ld: main.c:(.text+0xbc7): undefined reference to
> > > `qat_vfmig_load_state'
> >
> > at a glance those undefined symbols don't use any symbol under
> > IOV. They are just wrappers to certain callbacks registered by
> > by respective qat drivers which support migration.
> >
> > Probably they'd better be moved out of CONFIG_PCI_IOV in
> > "drivers/crypto/intel/qat/qat_common/Makefile" to remove
> > this dependency in vfio variant driver.
> >
> 
> Thanks, Kevin :-). This dependency is like the relationship between the QAT
> vfio
> variant driver and macro CRYPTO_DEV_QAT_4XXX. The variant driver doesn't
> directly reference the symbols exported by module qat_4xxx which is
> protected
> by CRYPTO_DEV_QAT_4XXX, but requires the module qat_4xxx at runtime so
> far.
> Alex suggested to put CRYPTO_DEV_QAT_4XXX as the dependency of this
> variant
> driver.
> For CONFIG_PCI_IOV, if it is disabled, this variant driver doesn't serve the
> user as
> well since no VFs will be created by QAT PF driver. To keep the consistency, it
> might
> be right to make it as the dependency of this variant driver as Arnd pointed
> out.
> What do you think?
> 

Following this rationale then we need also make PCI_IOV a dependency
for mlx5 and hisilicon given they are for VF migration too?