1 #include <linux/hardirq.h> 2 3 #include <asm/x86_init.h> 4 5 #include <xen/interface/xen.h> 6 #include <xen/interface/sched.h> 7 #include <xen/interface/vcpu.h> 8 #include <xen/events.h> 9 10 #include <asm/xen/hypercall.h> 11 #include <asm/xen/hypervisor.h> 12 13 #include "xen-ops.h" 14 15 /* 16 * Force a proper event-channel callback from Xen after clearing the 17 * callback mask. We do this in a very simple manner, by making a call 18 * down into Xen. The pending flag will be checked by Xen on return. 19 */ 20 void xen_force_evtchn_callback(void) 21 { 22 (void)HYPERVISOR_xen_version(0, NULL); 23 } 24 25 static unsigned long xen_save_fl(void) 26 { 27 struct vcpu_info *vcpu; 28 unsigned long flags; 29 30 vcpu = this_cpu_read(xen_vcpu); 31 32 /* flag has opposite sense of mask */ 33 flags = !vcpu->evtchn_upcall_mask; 34 35 /* convert to IF type flag 36 -0 -> 0x00000000 37 -1 -> 0xffffffff 38 */ 39 return (-flags) & X86_EFLAGS_IF; 40 } 41 PV_CALLEE_SAVE_REGS_THUNK(xen_save_fl); 42 43 static void xen_restore_fl(unsigned long flags) 44 { 45 struct vcpu_info *vcpu; 46 47 /* convert from IF type flag */ 48 flags = !(flags & X86_EFLAGS_IF); 49 50 /* There's a one instruction preempt window here. We need to 51 make sure we're don't switch CPUs between getting the vcpu 52 pointer and updating the mask. */ 53 preempt_disable(); 54 vcpu = this_cpu_read(xen_vcpu); 55 vcpu->evtchn_upcall_mask = flags; 56 preempt_enable_no_resched(); 57 58 /* Doesn't matter if we get preempted here, because any 59 pending event will get dealt with anyway. */ 60 61 if (flags == 0) { 62 preempt_check_resched(); 63 barrier(); /* unmask then check (avoid races) */ 64 if (unlikely(vcpu->evtchn_upcall_pending)) 65 xen_force_evtchn_callback(); 66 } 67 } 68 PV_CALLEE_SAVE_REGS_THUNK(xen_restore_fl); 69 70 static void xen_irq_disable(void) 71 { 72 /* There's a one instruction preempt window here. We need to 73 make sure we're don't switch CPUs between getting the vcpu 74 pointer and updating the mask. */ 75 preempt_disable(); 76 this_cpu_read(xen_vcpu)->evtchn_upcall_mask = 1; 77 preempt_enable_no_resched(); 78 } 79 PV_CALLEE_SAVE_REGS_THUNK(xen_irq_disable); 80 81 static void xen_irq_enable(void) 82 { 83 struct vcpu_info *vcpu; 84 85 /* We don't need to worry about being preempted here, since 86 either a) interrupts are disabled, so no preemption, or b) 87 the caller is confused and is trying to re-enable interrupts 88 on an indeterminate processor. */ 89 90 vcpu = this_cpu_read(xen_vcpu); 91 vcpu->evtchn_upcall_mask = 0; 92 93 /* Doesn't matter if we get preempted here, because any 94 pending event will get dealt with anyway. */ 95 96 barrier(); /* unmask then check (avoid races) */ 97 if (unlikely(vcpu->evtchn_upcall_pending)) 98 xen_force_evtchn_callback(); 99 } 100 PV_CALLEE_SAVE_REGS_THUNK(xen_irq_enable); 101 102 static void xen_safe_halt(void) 103 { 104 /* Blocking includes an implicit local_irq_enable(). */ 105 if (HYPERVISOR_sched_op(SCHEDOP_block, NULL) != 0) 106 BUG(); 107 } 108 109 static void xen_halt(void) 110 { 111 if (irqs_disabled()) 112 HYPERVISOR_vcpu_op(VCPUOP_down, smp_processor_id(), NULL); 113 else 114 xen_safe_halt(); 115 } 116 117 static const struct pv_irq_ops xen_irq_ops __initconst = { 118 .save_fl = PV_CALLEE_SAVE(xen_save_fl), 119 .restore_fl = PV_CALLEE_SAVE(xen_restore_fl), 120 .irq_disable = PV_CALLEE_SAVE(xen_irq_disable), 121 .irq_enable = PV_CALLEE_SAVE(xen_irq_enable), 122 123 .safe_halt = xen_safe_halt, 124 .halt = xen_halt, 125 #ifdef CONFIG_X86_64 126 .adjust_exception_frame = xen_adjust_exception_frame, 127 #endif 128 }; 129 130 void __init xen_init_irq_ops(void) 131 { 132 pv_irq_ops = xen_irq_ops; 133 x86_init.irqs.intr_init = xen_init_IRQ; 134 } 135