[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH 3/5] xen/smp: Update pv_lock_ops functions before alternative code starts under PVHVM
On 07/09/13 14:46, Konrad Rzeszutek Wilk wrote: > Before this patch we would patch all of the pv_lock_ops sites > using alternative assembler. Then later in the bootup cycle > change the unlock_kick and lock_spinning to the Xen specific - > without re patching. > > That meant that for the core of the kernel we would be running > with the baremetal version of unlock_kick and lock_spinning while > for modules we would have the proper Xen specific slowpaths. > > As most of the module uses some API from the core kernel that ended > up with slowpath lockers waiting forever to be kicked (b/c they > would be using the Xen specific slowpath logic). And the > kick never came b/c the unlock path that was taken was the > baremetal one. > > On PV we do not have the problem as we initialise before the > alternative code kicks in. > > The fix is to move the updating of the pv_lock_ops function > before the alternative code starts patching. This comment seems odd. The xen_spinlock_init() call is added not moved. > --- a/arch/x86/xen/smp.c > +++ b/arch/x86/xen/smp.c > @@ -731,4 +731,12 @@ void __init xen_hvm_smp_init(void) > smp_ops.cpu_die = xen_hvm_cpu_die; > smp_ops.send_call_func_ipi = xen_smp_send_call_function_ipi; > smp_ops.send_call_func_single_ipi = > xen_smp_send_call_function_single_ipi; > + > + /* > + * The alternative logic (which patches the unlock/lock) runs before > + * the smp bootup up code is activated. That meant we would never patch > + * the core of the kernel with proper paravirt interfaces but would > patch > + * modules. > + */ > + xen_init_spinlocks(); PV does this in xen_smp_prepare_boot_cpu. It would be better if the PVHVM case followed this same pattern and provide a smp_prepare_boot_cpu implementation to do this? David _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
|
Lists.xenproject.org is hosted with RackSpace, monitoring our |