RE: [RFC PATCH v2] PCI: hv: Avoid the retarget interrupt hypercall in irq_unmask() on ARM64

[Michael Kelley (LINUX)]

From: Boqun Feng <boqun.feng@xxxxxxxxx> Sent: Wednesday, February 16, 2022 7:45 PM
> 
> On ARM64 Hyper-V guests, SPIs are used for the interrupts of virtual PCI
> devices, and SPIs can be managed directly via GICD registers. Therefore
> the retarget interrupt hypercall is not needed on ARM64.
> 
> An arch-specific interface hv_arch_irq_unmask() is introduced to handle
> the architecture level differences on this. For x86, the behavior
> remains unchanged, while for ARM64 no hypercall is invoked when
> unmasking an irq for virtual PCI devices.
> 
> Signed-off-by: Boqun Feng <boqun.feng@xxxxxxxxx>
> ---
> v1 -> v2:
> 
> *	Introduce arch-specific interface hv_arch_irq_unmask() as
> 	suggested by Bjorn
> 
>  drivers/pci/controller/pci-hyperv.c | 233 +++++++++++++++-------------
>  1 file changed, 122 insertions(+), 111 deletions(-)

Reviewed-by: Michael Kelley <mikelley@xxxxxxxxxxxxx>