clocksource/drivers/hyper-v: Move handling of STIMER0 interrupts

STIMER0 interrupts are most naturally modeled as per-cpu IRQs. But
because x86/x64 doesn't have per-cpu IRQs, the core STIMER0 interrupt
handling machinery is done in code under arch/x86 and Linux IRQs are
not used. Adding support for ARM64 means adding equivalent code
using per-cpu IRQs under arch/arm64.

A better model is to treat per-cpu IRQs as the normal path (which it is
for modern architectures), and the x86/x64 path as the exception. Do this
by incorporating standard Linux per-cpu IRQ allocation into the main
SITMER0 driver code, and bypass it in the x86/x64 exception case. For
x86/x64, special case code is retained under arch/x86, but no STIMER0
interrupt handling code is needed under arch/arm64.

No functional change.

Signed-off-by: Michael Kelley <mikelley@microsoft.com>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/1614721102-2241-11-git-send-email-mikelley@microsoft.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>

1 files changed, 3 insertions, 7 deletions

diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
index 41fd84a88783..cebed535ec56 100644
--- a/arch/x86/kernel/cpu/mshyperv.c
+++ b/arch/x86/kernel/cpu/mshyperv.c
@@ -90,21 +90,17 @@ DEFINE_IDTENTRY_SYSVEC(sysvec_hyperv_stimer0)
 	set_irq_regs(old_regs);
 }
 
-int hv_setup_stimer0_irq(int *irq, int *vector, void (*handler)(void))
+/* For x86/x64, override weak placeholders in hyperv_timer.c */
+void hv_setup_stimer0_handler(void (*handler)(void))
 {
-	*vector = HYPERV_STIMER0_VECTOR;
-	*irq = -1;   /* Unused on x86/x64 */
 	hv_stimer0_handler = handler;
-	return 0;
 }
-EXPORT_SYMBOL_GPL(hv_setup_stimer0_irq);
 
-void hv_remove_stimer0_irq(int irq)
+void hv_remove_stimer0_handler(void)
 {
 	/* We have no way to deallocate the interrupt gate */
 	hv_stimer0_handler = NULL;
 }
-EXPORT_SYMBOL_GPL(hv_remove_stimer0_irq);
 
 void hv_setup_kexec_handler(void (*handler)(void))
 {