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792dc4f6cd
Rather than overloading vectors for event channels, take full responsibility for mapping an event channel to irq directly. With this patch Xen has its own irq allocator. When the kernel gets an event channel upcall, it maps the event channel number to an irq and injects it into the normal interrupt path. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
133 lines
3.3 KiB
C
133 lines
3.3 KiB
C
#include <linux/hardirq.h>
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#include <xen/interface/xen.h>
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#include <xen/interface/sched.h>
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#include <xen/interface/vcpu.h>
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#include <asm/xen/hypercall.h>
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#include <asm/xen/hypervisor.h>
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#include "xen-ops.h"
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/*
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* Force a proper event-channel callback from Xen after clearing the
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* callback mask. We do this in a very simple manner, by making a call
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* down into Xen. The pending flag will be checked by Xen on return.
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*/
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void xen_force_evtchn_callback(void)
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{
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(void)HYPERVISOR_xen_version(0, NULL);
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}
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static unsigned long xen_save_fl(void)
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{
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struct vcpu_info *vcpu;
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unsigned long flags;
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vcpu = percpu_read(xen_vcpu);
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/* flag has opposite sense of mask */
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flags = !vcpu->evtchn_upcall_mask;
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/* convert to IF type flag
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-0 -> 0x00000000
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-1 -> 0xffffffff
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*/
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return (-flags) & X86_EFLAGS_IF;
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}
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PV_CALLEE_SAVE_REGS_THUNK(xen_save_fl);
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static void xen_restore_fl(unsigned long flags)
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{
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struct vcpu_info *vcpu;
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/* convert from IF type flag */
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flags = !(flags & X86_EFLAGS_IF);
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/* There's a one instruction preempt window here. We need to
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make sure we're don't switch CPUs between getting the vcpu
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pointer and updating the mask. */
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preempt_disable();
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vcpu = percpu_read(xen_vcpu);
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vcpu->evtchn_upcall_mask = flags;
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preempt_enable_no_resched();
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/* Doesn't matter if we get preempted here, because any
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pending event will get dealt with anyway. */
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if (flags == 0) {
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preempt_check_resched();
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barrier(); /* unmask then check (avoid races) */
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if (unlikely(vcpu->evtchn_upcall_pending))
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xen_force_evtchn_callback();
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}
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}
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PV_CALLEE_SAVE_REGS_THUNK(xen_restore_fl);
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static void xen_irq_disable(void)
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{
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/* There's a one instruction preempt window here. We need to
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make sure we're don't switch CPUs between getting the vcpu
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pointer and updating the mask. */
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preempt_disable();
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percpu_read(xen_vcpu)->evtchn_upcall_mask = 1;
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preempt_enable_no_resched();
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}
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PV_CALLEE_SAVE_REGS_THUNK(xen_irq_disable);
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static void xen_irq_enable(void)
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{
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struct vcpu_info *vcpu;
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/* We don't need to worry about being preempted here, since
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either a) interrupts are disabled, so no preemption, or b)
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the caller is confused and is trying to re-enable interrupts
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on an indeterminate processor. */
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vcpu = percpu_read(xen_vcpu);
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vcpu->evtchn_upcall_mask = 0;
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/* Doesn't matter if we get preempted here, because any
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pending event will get dealt with anyway. */
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barrier(); /* unmask then check (avoid races) */
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if (unlikely(vcpu->evtchn_upcall_pending))
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xen_force_evtchn_callback();
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}
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PV_CALLEE_SAVE_REGS_THUNK(xen_irq_enable);
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static void xen_safe_halt(void)
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{
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/* Blocking includes an implicit local_irq_enable(). */
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if (HYPERVISOR_sched_op(SCHEDOP_block, NULL) != 0)
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BUG();
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}
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static void xen_halt(void)
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{
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if (irqs_disabled())
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HYPERVISOR_vcpu_op(VCPUOP_down, smp_processor_id(), NULL);
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else
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xen_safe_halt();
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}
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static const struct pv_irq_ops xen_irq_ops __initdata = {
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.init_IRQ = xen_init_IRQ,
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.save_fl = PV_CALLEE_SAVE(xen_save_fl),
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.restore_fl = PV_CALLEE_SAVE(xen_restore_fl),
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.irq_disable = PV_CALLEE_SAVE(xen_irq_disable),
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.irq_enable = PV_CALLEE_SAVE(xen_irq_enable),
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.safe_halt = xen_safe_halt,
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.halt = xen_halt,
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#ifdef CONFIG_X86_64
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.adjust_exception_frame = xen_adjust_exception_frame,
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#endif
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};
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void __init xen_init_irq_ops()
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{
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pv_irq_ops = xen_irq_ops;
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}
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