From 3d53c27d05950390712f92c5ad1604c60190ed64 Mon Sep 17 00:00:00 2001 From: Avi Kivity Date: Tue, 1 Sep 2009 12:34:07 +0300 Subject: [PATCH] KVM: Use thread debug register storage instead of kvm specific data Instead of saving the debug registers from the processor to a kvm data structure, rely in the debug registers stored in the thread structure. This allows us not to save dr6 and dr7. Reduces lightweight vmexit cost by 350 cycles, or 11 percent. Signed-off-by: Avi Kivity --- arch/x86/include/asm/kvm_host.h | 3 --- arch/x86/kvm/x86.c | 22 +++++++--------------- 2 files changed, 7 insertions(+), 18 deletions(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 33901be75a3..e8f166a02c7 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -362,9 +362,6 @@ struct kvm_vcpu_arch { u32 pat; int switch_db_regs; - unsigned long host_db[KVM_NR_DB_REGS]; - unsigned long host_dr6; - unsigned long host_dr7; unsigned long db[KVM_NR_DB_REGS]; unsigned long dr6; unsigned long dr7; diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 35e7fc54de3..3e893c4fdd3 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -3623,14 +3623,7 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run) kvm_guest_enter(); - get_debugreg(vcpu->arch.host_dr6, 6); - get_debugreg(vcpu->arch.host_dr7, 7); if (unlikely(vcpu->arch.switch_db_regs)) { - get_debugreg(vcpu->arch.host_db[0], 0); - get_debugreg(vcpu->arch.host_db[1], 1); - get_debugreg(vcpu->arch.host_db[2], 2); - get_debugreg(vcpu->arch.host_db[3], 3); - set_debugreg(0, 7); set_debugreg(vcpu->arch.eff_db[0], 0); set_debugreg(vcpu->arch.eff_db[1], 1); @@ -3641,15 +3634,14 @@ 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)) { - set_debugreg(0, 7); - set_debugreg(vcpu->arch.host_db[0], 0); - set_debugreg(vcpu->arch.host_db[1], 1); - set_debugreg(vcpu->arch.host_db[2], 2); - set_debugreg(vcpu->arch.host_db[3], 3); + if (unlikely(vcpu->arch.switch_db_regs || test_thread_flag(TIF_DEBUG))) { + set_debugreg(current->thread.debugreg0, 0); + set_debugreg(current->thread.debugreg1, 1); + set_debugreg(current->thread.debugreg2, 2); + set_debugreg(current->thread.debugreg3, 3); + set_debugreg(current->thread.debugreg6, 6); + set_debugreg(current->thread.debugreg7, 7); } - set_debugreg(vcpu->arch.host_dr6, 6); - set_debugreg(vcpu->arch.host_dr7, 7); set_bit(KVM_REQ_KICK, &vcpu->requests); local_irq_enable(); -- 2.20.1