From 0d651e4e65e96989f72236bf83bd4c6e55eb6ce4 Mon Sep 17 00:00:00 2001 From: Mark Rutland Date: Wed, 30 Jan 2013 17:51:26 +0000 Subject: clocksource: arch_timer: use virtual counters Switching between reading the virtual or physical counters is problematic, as some core code wants a view of time before we're fully set up. Using a function pointer and switching the source after the first read can make time appear to go backwards, and having a check in the read function is an unfortunate block on what we want to be a fast path. Instead, this patch makes us always use the virtual counters. If we're a guest, or don't have hyp mode, we'll use the virtual timers, and as such don't care about CNTVOFF as long as it doesn't change in such a way as to make time appear to travel backwards. As the guest will use the virtual timers, a (potential) KVM host must use the physical timers (which can wake up the host even if they fire while a guest is executing), and hence a host must have CNTVOFF set to zero so as to have a consistent view of time between the physical timers and virtual counters. Signed-off-by: Mark Rutland Acked-by: Catalin Marinas Acked-by: Marc Zyngier Acked-by: Santosh Shilimkar Cc: Rob Herring --- arch/arm/include/asm/arch_timer.h | 9 --------- 1 file changed, 9 deletions(-) (limited to 'arch/arm/include/asm') diff --git a/arch/arm/include/asm/arch_timer.h b/arch/arm/include/asm/arch_timer.h index 7c1bfc0aea0c..accefe099182 100644 --- a/arch/arm/include/asm/arch_timer.h +++ b/arch/arm/include/asm/arch_timer.h @@ -80,15 +80,6 @@ static inline u32 arch_timer_get_cntfrq(void) return val; } -static inline u64 arch_counter_get_cntpct(void) -{ - u64 cval; - - isb(); - asm volatile("mrrc p15, 0, %Q0, %R0, c14" : "=r" (cval)); - return cval; -} - static inline u64 arch_counter_get_cntvct(void) { u64 cval; -- cgit v1.2.3-59-g8ed1b