Messages in this thread |  | | Date | Thu, 27 Jan 2022 09:45:02 -0500 | Subject | Re: [RFC PATCH] s390: vfio-ap: Register the vfio_ap module for the "ap" parent bus | From | Tony Krowiak <> |
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On 12/13/21 10:44, Harald Freudenberger wrote: > On 01.12.21 15:11, Thomas Huth wrote: >> The crypto devices that we can use with the vfio_ap module are sitting >> on the "ap" bus, not on the "vfio_ap" bus that the module defines >> itself. With this change, the vfio_ap module now gets automatically >> loaded if a supported crypto adapter is available in the host. >> >> Signed-off-by: Thomas Huth <thuth@redhat.com> >> --- >> Note: Marked as "RFC" since I'm not 100% sure about it ... >> please review carefully! >> >> drivers/s390/crypto/vfio_ap_drv.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/drivers/s390/crypto/vfio_ap_drv.c b/drivers/s390/crypto/vfio_ap_drv.c >> index 4d2556bc7fe5..5580e40608a4 100644 >> --- a/drivers/s390/crypto/vfio_ap_drv.c >> +++ b/drivers/s390/crypto/vfio_ap_drv.c >> @@ -39,7 +39,7 @@ static struct ap_device_id ap_queue_ids[] = { >> { /* end of sibling */ }, >> }; >> >> -MODULE_DEVICE_TABLE(vfio_ap, ap_queue_ids); >> +MODULE_DEVICE_TABLE(ap, ap_queue_ids); >> >> /** >> * vfio_ap_queue_dev_probe: > I had a chance to check this now. > First I have to apologize about the dispute with vfio devices appearing on the ap bus. > That's not the case with this patch. As Connie states the MODULE_DEVICE_TABLE() does not > change the parent of a device and vfio_ap_drv is a driver for ap devices and thus > belongs to the ap bus anyway. > So what's left is that with this change the vfio_ap kernel module is automatically loaded > when an ap device type 10-13 is recognized by the ap bus. So the intention of the patch > is fulfilled. > Yet another kernel module which may occupy memory but will never get used by most customers. > This may not be a problem but I had a glance at the list of kernel modules loaded on my > LPAR with and without the patch and the difference is: > ... > kvm 512000 1 vfio_ap > vfio_ap 28672 0 > ... > So the vfio_ap module has a dependency to the biggest kernel module ever - kvm. > Do I need to say something more? > > If this dependency is removed then I would not hesitate to accept this patch. However > this is up to Tony as he is the maintainer of the vfio ap device driver.
Since the vfio_ccw module also needs the kvm module and is automatically loaded, I see no problem with automatically loading the vfio_ap module. I tested this patch by running all of my regression tests successfully.
> >
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