On 22/10/2018 03:53, Yi Sun wrote: > On 18-10-19 16:20:52, Juergen Gross wrote: >> On 19/10/2018 15:13, Yi Sun wrote: > > [...] > >>> diff --git a/kernel/locking/qspinlock_paravirt.h >>> b/kernel/locking/qspinlock_paravirt.h >>> index 0130e48..9e88c7e 100644 >>> --- a/kernel/locking/qspinlock_paravirt.h >>> +++ b/kernel/locking/qspinlock_paravirt.h >>> @@ -7,6 +7,8 @@ >>> #include <linux/bootmem.h> >>> #include <linux/debug_locks.h> >>> >>> +#include <asm/mshyperv.h> >>> + >>> /* >>> * Implement paravirt qspinlocks; the general idea is to halt the vcpus >>> instead >>> * of spinning them. >>> @@ -305,6 +307,10 @@ static void pv_wait_node(struct mcs_spinlock *node, >>> struct mcs_spinlock *prev) >>> wait_early = true; >>> break; >>> } >>> +#if defined(CONFIG_X86_64) && defined(CONFIG_PARAVIRT_SPINLOCKS) && >>> IS_ENABLED(CONFIG_HYPERV) >>> + if (!hv_notify_long_spin_wait(SPIN_THRESHOLD - loop)) >>> + break; >>> +#endif >> >> I don't like that. Why should a KVM or Xen guest call into a hyperv >> specific function? >> >> Can't you move this to existing hyperv specific paravirt hooks? >> > hv_notify_long_spin_wait() must be called in this loop but it seems > there is no appropriate existing paravirt hook here. So, can I add > one more hook in pv_lock_ops to do this notification?
vcpu_is_preempted() is already part of this loop. And this is a paravirt hook. Can't you make use of that? This might require adding another parameter to this hook, but I'd prefer that over another pv-spinlock hook. Adding some more locking maintainers and Waiman to the Cc: list. Juergen