KVM: x86: fix root cause for missed hardware breakpoints
commit 70e4da7a8ff62f2775337b705f45c804bb450454 upstream. Commit 172b2386ed16 ("KVM: x86: fix missed hardware breakpoints", 2016-02-10) worked around a case where the debug registers are not loaded correctly on preemption and on the first entry to KVM_RUN. However, Xiao Guangrong pointed out that the root cause must be that KVM_DEBUGREG_BP_ENABLED is not being set correctly. This can indeed happen due to the lazy debug exit mechanism, which does not call kvm_update_dr7. Fix it by replacing the existing loop (more or less equivalent to kvm_update_dr0123) with calls to all the kvm_update_dr* functions. Fixes: 172b2386ed16a9143d9a456aae5ec87275c61489 Reviewed-by: Xiao Guangrong <guangrong.xiao@linux.intel.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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1 changed files with 4 additions and 5 deletions
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@ -2736,7 +2736,6 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
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}
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kvm_make_request(KVM_REQ_STEAL_UPDATE, vcpu);
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vcpu->arch.switch_db_regs |= KVM_DEBUGREG_RELOAD;
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}
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void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
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@ -6545,12 +6544,12 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
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* KVM_DEBUGREG_WONT_EXIT again.
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*/
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if (unlikely(vcpu->arch.switch_db_regs & KVM_DEBUGREG_WONT_EXIT)) {
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int i;
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WARN_ON(vcpu->guest_debug & KVM_GUESTDBG_USE_HW_BP);
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kvm_x86_ops->sync_dirty_debug_regs(vcpu);
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for (i = 0; i < KVM_NR_DB_REGS; i++)
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vcpu->arch.eff_db[i] = vcpu->arch.db[i];
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kvm_update_dr0123(vcpu);
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kvm_update_dr6(vcpu);
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kvm_update_dr7(vcpu);
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vcpu->arch.switch_db_regs &= ~KVM_DEBUGREG_RELOAD;
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}
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/*
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