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 asmlinkage 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 __visible 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 /* See xen_irq_enable() for why preemption must be disabled. */ 51 preempt_disable(); 52 vcpu = this_cpu_read(xen_vcpu); 53 vcpu->evtchn_upcall_mask = flags; 54 55 if (flags == 0) { 56 barrier(); /* unmask then check (avoid races) */ 57 if (unlikely(vcpu->evtchn_upcall_pending)) 58 xen_force_evtchn_callback(); 59 preempt_enable(); 60 } else 61 preempt_enable_no_resched(); 62 } 63 PV_CALLEE_SAVE_REGS_THUNK(xen_restore_fl); 64 65 asmlinkage void xen_irq_disable(void) 66 { 67 /* There's a one instruction preempt window here. We need to 68 make sure we're don't switch CPUs between getting the vcpu 69 pointer and updating the mask. */ 70 preempt_disable(); 71 this_cpu_read(xen_vcpu)->evtchn_upcall_mask = 1; 72 preempt_enable_no_resched(); 73 } 74 PV_CALLEE_SAVE_REGS_THUNK(xen_irq_disable); 75 76 asmlinkage void xen_irq_enable(void) 77 { 78 struct vcpu_info *vcpu; 79 80 /* 81 * We may be preempted as soon as vcpu->evtchn_upcall_mask is 82 * cleared, so disable preemption to ensure we check for 83 * events on the VCPU we are still running on. 84 */ 85 preempt_disable(); 86 87 vcpu = this_cpu_read(xen_vcpu); 88 vcpu->evtchn_upcall_mask = 0; 89 90 /* Doesn't matter if we get preempted here, because any 91 pending event will get dealt with anyway. */ 92 93 barrier(); /* unmask then check (avoid races) */ 94 if (unlikely(vcpu->evtchn_upcall_pending)) 95 xen_force_evtchn_callback(); 96 97 preempt_enable(); 98 } 99 PV_CALLEE_SAVE_REGS_THUNK(xen_irq_enable); 100 101 static void xen_safe_halt(void) 102 { 103 /* Blocking includes an implicit local_irq_enable(). */ 104 if (HYPERVISOR_sched_op(SCHEDOP_block, NULL) != 0) 105 BUG(); 106 } 107 108 static void xen_halt(void) 109 { 110 if (irqs_disabled()) 111 HYPERVISOR_vcpu_op(VCPUOP_down, smp_processor_id(), NULL); 112 else 113 xen_safe_halt(); 114 } 115 116 static const struct pv_irq_ops xen_irq_ops __initconst = { 117 .save_fl = PV_CALLEE_SAVE(xen_save_fl), 118 .restore_fl = PV_CALLEE_SAVE(xen_restore_fl), 119 .irq_disable = PV_CALLEE_SAVE(xen_irq_disable), 120 .irq_enable = PV_CALLEE_SAVE(xen_irq_enable), 121 122 .safe_halt = xen_safe_halt, 123 .halt = xen_halt, 124 #ifdef CONFIG_X86_64 125 .adjust_exception_frame = xen_adjust_exception_frame, 126 #endif 127 }; 128 129 void __init xen_init_irq_ops(void) 130 { 131 pv_irq_ops = xen_irq_ops; 132 x86_init.irqs.intr_init = xen_init_IRQ; 133 } 134