On Mon, Jan 27, 2025 at 09:02:22PM +0000, Michael Kelley wrote: > From: Hamza Mahfooz <hamzamahfooz@xxxxxxxxxxxxxxxxxxx> Sent: Monday, January 27, 2025 10:10 AM > > > > We should select PCI_HYPERV here, otherwise it's possible for devices to > > not show up as expected, at least not in an orderly manner. > > The commit message needs more precision: What does "not show up" > mean, and what does "not in an orderly manner" mean? And "it's possible" > is vague -- can you be more specific about the conditions? Also, avoid > the use of personal pronouns like "we". > > But the commit message notwithstanding, I don't think this is change > that should be made. CONFIG_PCI_HYPERV refers to the VMBus device > driver for handling vPCI (a.k.a PCI pass-thru) devices. It's perfectly > possible and normal for a VM on Hyper-V to not have any such devices, > in which case the driver isn't needed and should not be forced to be > included. (See Documentation/virt/hyperv/vpci.rst for more on vPCI > devices.) Ya, we ran into an issue where CONFIG_NVME_CORE=y and CONFIG_PCI_HYPERV=m caused the passed-through SSDs not to show up (i.e. they aren't visible to userspace). I guess it's cause PCI_HYPERV has to load in before the nvme stuff for that workload. So, I thought it was reasonable to select PCI_HYPERV here to prevent someone else from shooting themselves in the foot. Though, I guess it really it on the distro guys to get that right. > > There are other VMBus device drivers: storvsc, netvsc, the Hyper-V > frame buffer driver, the "util" drivers for shutdown, KVP, etc., and more. > These each have their own CONFIG_* entry, and current practice > doesn't select them when CONFIG_HYPERV is set. I don't see a reason > that the vPCI driver should be handled differently. > > Also, different distro vendors take different approaches as to whether > these drivers are built as modules, or as built-in to their kernel images. > I'm not sure what the Kconfig tool does when a SELECT statement identifies > a tri-state setting. Since CONFIG_HYPERV is tri-state, does the target of > the SELECT get the same tri-state value as CONFIG_HYPERV? Again, > that may not be what distro vendors want. They may choose to have > some of the VMBus drivers built-in and others built as modules. Distro > vendors (and anyone doing a custom kernel build) should be allowed > to make their choices just like for any other drivers. > > If you've come across a situation these considerations don't apply > or are problematic, provide more details. That's what a good commit > message should do -- be convincing as to *why* the change should > be made! :-) > > Michael > > > > > Cc: stable@xxxxxxxxxxxxxxx > > Cc: Wei Liu <wei.liu@xxxxxxxxxx> > > Signed-off-by: Hamza Mahfooz <hamzamahfooz@xxxxxxxxxxxxxxxxxxx> > > --- > > drivers/hv/Kconfig | 1 + > > 1 file changed, 1 insertion(+) > > > > diff --git a/drivers/hv/Kconfig b/drivers/hv/Kconfig > > index 862c47b191af..6ee75b3f0fa6 100644 > > --- a/drivers/hv/Kconfig > > +++ b/drivers/hv/Kconfig > > @@ -9,6 +9,7 @@ config HYPERV > > select PARAVIRT > > select X86_HV_CALLBACK_VECTOR if X86 > > select OF_EARLY_FLATTREE if OF > > + select PCI_HYPERV if PCI > > help > > Select this option to run Linux as a Hyper-V client operating > > system. > > -- > > 2.47.1 > > >
