hw-breakpoints: Rewrite the hw-breakpoints layer on top of perf events

[linux-2.6-block.git] / arch / x86 / kvm / x86.c

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index fc2974adf9b65a3933345dcec24e051b925b66d2..22dee7aa7813973e895595ebbc879a1a5e87685f 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -42,6 +42,7 @@
 #define CREATE_TRACE_POINTS
 #include "trace.h"
 
+#include <asm/debugreg.h>
 #include <asm/uaccess.h>
 #include <asm/msr.h>
 #include <asm/desc.h>
@@ -3643,14 +3644,15 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
        trace_kvm_entry(vcpu->vcpu_id);
        kvm_x86_ops->run(vcpu, kvm_run);
 
-       if (unlikely(vcpu->arch.switch_db_regs || test_thread_flag(TIF_DEBUG))) {
-               set_debugreg(current->thread.debugreg[0], 0);
-               set_debugreg(current->thread.debugreg[1], 1);
-               set_debugreg(current->thread.debugreg[2], 2);
-               set_debugreg(current->thread.debugreg[3], 3);
-               set_debugreg(current->thread.debugreg6, 6);
-               set_debugreg(current->thread.debugreg7, 7);
-       }
+       /*
+        * If the guest has used debug registers, at least dr7
+        * will be disabled while returning to the host.
+        * If we don't have active breakpoints in the host, we don't
+        * care about the messed up debug address registers. But if
+        * we have some of them active, restore the old state.
+        */
+       if (__get_cpu_var(dr7) & DR_GLOBAL_ENABLE_MASK)
+               hw_breakpoint_restore();
 
        set_bit(KVM_REQ_KICK, &vcpu->requests);
        local_irq_enable();