> diff -r ccb713d46376 linux-2.6-xen-sparse/arch/ia64/xen/hypercall.S
Can a macro be used instead of repeating same assembler sequence to set vpsr.ic = 0? On Wed, Mar 29, 2006 at 09:49:38PM +0800, Tian, Kevin wrote: > This patch merges current interrupt_delivery_enabled on xen/ia64 with > evtchn_upcall_mask in shared_info_area. Currently when guest clears > vpsr.i, interrupt_delivery_enabled is cleared correspondingly to prevent > further interrupt injection. However evtchn_upcall_mask is left > untouched, > which makes event_pending(v) check valid and thus may result a window > to drop guest into dead loop. For example: > > 1. Guest disable interrupts > (interrupt_delivery_enabled:0 evtchn_upcall_mask:0) > 2. Guest calls a hypercall, like do_console_io with CONSOLEIO_write > 3. guest_console_write in Xen will check whether any events pending to > preempt current hypercall. If pending with evtchn_upcall_mask cleared, > create a continuation context and resume to guest to re-execute > hypercall > 4. Before resuming to guest, xen checks whether any pending interrupts > to inject into guest. However because guest interrupt is disabled, > pending > events won't be injected into guest and still pends there > 5. Then guest re-executes hypercall, and back to step 2 and INFINITE > loop occurs because events are not handled > > One typical example is timer oops message occurring in guest timer > handler, which may halt the machine sometimes if events happen to pend > there due to above reason. > > So in this case, we need update evtchn_upcall_mask together with > Interrupt delivery enabled flag. However there'll be some race > conditions > to operate two flags non-atomically. Actually since two flags serves for > > same purpose, it's better to merge them as one which also makes > xen/ia64 adapting to common code a bit since the latter always assumes > upon evtchn_upcall_mask. > > That's why this patch comes, and tested upon tip. > > Signed-off-by Kevin Tian <[EMAIL PROTECTED]> > > Thanks, > Kevin > _______________________________________________ > Xen-ia64-devel mailing list > Xen-ia64-devel@lists.xensource.com > http://lists.xensource.com/xen-ia64-devel -- yamahata _______________________________________________ Xen-ia64-devel mailing list Xen-ia64-devel@lists.xensource.com http://lists.xensource.com/xen-ia64-devel
