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/features.h> 9 #include <xen/events.h> 10 11 #include <asm/xen/hypercall.h> 12 #include <asm/xen/hypervisor.h> 13 14 #include "xen-ops.h" 15 16 /* 17 * Force a proper event-channel callback from Xen after clearing the 18 * callback mask. We do this in a very simple manner, by making a call 19 * down into Xen. The pending flag will be checked by Xen on return. 20 */ 21 void xen_force_evtchn_callback(void) 22 { 23 (void)HYPERVISOR_xen_version(0, NULL); 24 } 25 26 static unsigned long xen_save_fl(void) 27 { 28 struct vcpu_info *vcpu; 29 unsigned long flags; 30 31 vcpu = this_cpu_read(xen_vcpu); 32 33 /* flag has opposite sense of mask */ 34 flags = !vcpu->evtchn_upcall_mask; 35 36 /* convert to IF type flag 37 -0 -> 0x00000000 38 -1 -> 0xffffffff 39 */ 40 return (-flags) & X86_EFLAGS_IF; 41 } 42 PV_CALLEE_SAVE_REGS_THUNK(xen_save_fl); 43 44 static void xen_restore_fl(unsigned long flags) 45 { 46 struct vcpu_info *vcpu; 47 48 /* convert from IF type flag */ 49 flags = !(flags & X86_EFLAGS_IF); 50 51 /* See xen_irq_enable() for why preemption must be disabled. */ 52 preempt_disable(); 53 vcpu = this_cpu_read(xen_vcpu); 54 vcpu->evtchn_upcall_mask = flags; 55 56 if (flags == 0) { 57 barrier(); /* unmask then check (avoid races) */ 58 if (unlikely(vcpu->evtchn_upcall_pending)) 59 xen_force_evtchn_callback(); 60 preempt_enable(); 61 } else 62 preempt_enable_no_resched(); 63 } 64 PV_CALLEE_SAVE_REGS_THUNK(xen_restore_fl); 65 66 static void xen_irq_disable(void) 67 { 68 /* There's a one instruction preempt window here. We need to 69 make sure we're don't switch CPUs between getting the vcpu 70 pointer and updating the mask. */ 71 preempt_disable(); 72 this_cpu_read(xen_vcpu)->evtchn_upcall_mask = 1; 73 preempt_enable_no_resched(); 74 } 75 PV_CALLEE_SAVE_REGS_THUNK(xen_irq_disable); 76 77 static void xen_irq_enable(void) 78 { 79 struct vcpu_info *vcpu; 80 81 /* 82 * We may be preempted as soon as vcpu->evtchn_upcall_mask is 83 * cleared, so disable preemption to ensure we check for 84 * events on the VCPU we are still running on. 85 */ 86 preempt_disable(); 87 88 vcpu = this_cpu_read(xen_vcpu); 89 vcpu->evtchn_upcall_mask = 0; 90 91 /* Doesn't matter if we get preempted here, because any 92 pending event will get dealt with anyway. */ 93 94 barrier(); /* unmask then check (avoid races) */ 95 if (unlikely(vcpu->evtchn_upcall_pending)) 96 xen_force_evtchn_callback(); 97 98 preempt_enable(); 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 /* For PVH we use default pv_irq_ops settings. */ 133 if (!xen_feature(XENFEAT_hvm_callback_vector)) 134 pv_irq_ops = xen_irq_ops; 135 x86_init.irqs.intr_init = xen_init_IRQ; 136 } 137