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path: root/arch/x86/xen/xen-asm.S
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2012-04-27xen: correctly check for pending events when restoring irq flagsDavid Vrabel
In xen_restore_fl_direct(), xen_force_evtchn_callback() was being called even if no events were pending. This resulted in (depending on workload) about a 100 times as many xen_version hypercalls as necessary. Fix this by correcting the sense of the conditional jump. This seems to give a significant performance benefit for some workloads. There is some subtle tricksy "..since the check here is trying to check both pending and masked in a single cmpw, but I think this is correct. It will call check_events now only when the combined mask+pending word is 0x0001 (aka unmasked, pending)." (Ian) CC: stable@kernel.org Acked-by: Ian Campbell <ian.campbell@citrix.com> Signed-off-by: David Vrabel <david.vrabel@citrix.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2009-02-05x86: style cleanups for xen assembliesTejun Heo
Make the following style cleanups: * drop unnecessary //#include from xen-asm_32.S * compulsive adding of space after comma * reformat multiline comments Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-02-05xen: make direct versions of irq_enable/disable/save/restore to common codeJeremy Fitzhardinge
Now that x86-64 has directly accessible percpu variables, it can also implement the direct versions of these operations, which operate on a vcpu_info structure directly embedded in the percpu area. In fact, the 64-bit versions are more or less identical, and so can be shared. The only two differences are: 1. xen_restore_fl_direct takes its argument in eax on 32-bit, and rdi on 64-bit. Unfortunately it isn't possible to directly refer to the 2nd lsb of rdi directly (as you can with %ah), so the code isn't quite as dense. 2. check_events needs to variants to save different registers. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2008-07-16xen64: add 64-bit assemblerJeremy Fitzhardinge
Split xen-asm into 32- and 64-bit files, and implement the 64-bit variants. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Cc: Stephen Tweedie <sct@redhat.com> Cc: Eduardo Habkost <ehabkost@redhat.com> Cc: Mark McLoughlin <markmc@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-04-24xen: fold xen_sysexit into xen_iretJeremy Fitzhardinge
xen_sysexit and xen_iret were doing essentially the same thing. Rather than having a separate implementation for xen_sysexit, we can just strip the stack back to an iret frame and jump into xen_iret. This removes a lot of code and complexity - specifically, another critical region. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-04-24xen: jump to iret fixupJeremy Fitzhardinge
Use jmp rather than call for the iret fixup, so its consistent with the sysexit fixup, and it simplifies the stack (which is already complex). Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-04-24xen: support sysenter/sysexit if hypervisor doesJeremy Fitzhardinge
64-bit Xen supports sysenter for 32-bit guests, so support its use. (sysenter is faster than int $0x80 in 32-on-64.) sysexit is still not supported, so we fake it up using iret. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-04-24xen: make sure iret faults are trappedJeremy Fitzhardinge
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-04-17xen: use iret instruction all the timeJeremy Fitzhardinge
Change iret implementation to not be dependent on direct-access vcpu structure. Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-03-27xen: fix RMW when unmasking eventsJeremy Fitzhardinge
xen_irq_enable_direct and xen_sysexit were using "andw $0x00ff, XEN_vcpu_info_pending(vcpu)" to unmask events and test for pending ones in one instuction. Unfortunately, the pending flag must be modified with a locked operation since it can be set by another CPU, and the unlocked form of this operation was causing the pending flag to get lost, allowing the processor to return to usermode with pending events and ultimately deadlock. The simple fix would be to make it a locked operation, but that's rather costly and unnecessary. The fix here is to split the mask-clearing and pending-testing into two instructions; the interrupt window between them is of no concern because either way pending or new events will be processed. This should fix lingering bugs in using direct vcpu structure access too. [ Stable: needed in 2.6.24.x ] Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Cc: Stable <stable@kernel.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-11i386: move xenThomas Gleixner
Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@elte.hu>