Re: [Xen-devel] [PATCH v4 1/3] x86/ldt: Make modify_ldt synchronous

2015-07-25 Thread Borislav Petkov
On Fri, Jul 24, 2015 at 10:36:44PM -0700, Andy Lutomirski wrote: > modify_ldt has questionable locking and does not synchronize > threads. Improve it: redesign the locking and synchronize all > threads' LDTs using an IPI on all modifications. > > This will dramatically slow down modify_ldt in mul

[Xen-devel] [PATCH v4 1/3] x86/ldt: Make modify_ldt synchronous

2015-07-24 Thread Andy Lutomirski
modify_ldt has questionable locking and does not synchronize threads. Improve it: redesign the locking and synchronize all threads' LDTs using an IPI on all modifications. This will dramatically slow down modify_ldt in multithreaded programs, but there shouldn't be any multithreaded programs that