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authorPaolo Bonzini <pbonzini@redhat.com>2016-02-26 12:28:40 +0100
committerSasha Levin <sasha.levin@oracle.com>2016-03-09 13:15:10 -0500
commit18d609bb0b8c6823a750b32106be5685ca3daff7 (patch)
tree1029cb3396c12588e839d4be9afc750a713019f4
parentd017f850a3b6f84e6d847c6cbb01eaf6ce61f4f6 (diff)
KVM: x86: fix root cause for missed hardware breakpoints
[ Upstream commit 70e4da7a8ff62f2775337b705f45c804bb450454 ] 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. Cc: stable@vger.kernel.org # 4.1+ Fixes: 172b2386ed16a9143d9a456aae5ec87275c61489 Reviewed-by: Xiao Guangrong <guangrong.xiao@linux.intel.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
-rw-r--r--arch/x86/kvm/x86.c9
1 files changed, 4 insertions, 5 deletions
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 0dbf28a6d83d..42f1575ab58d 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2968,7 +2968,6 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
accumulate_steal_time(vcpu);
kvm_make_request(KVM_REQ_STEAL_UPDATE, vcpu);
- vcpu->arch.switch_db_regs |= KVM_DEBUGREG_RELOAD;
}
void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
@@ -6372,12 +6371,12 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
* KVM_DEBUGREG_WONT_EXIT again.
*/
if (unlikely(vcpu->arch.switch_db_regs & KVM_DEBUGREG_WONT_EXIT)) {
- int i;
-
WARN_ON(vcpu->guest_debug & KVM_GUESTDBG_USE_HW_BP);
kvm_x86_ops->sync_dirty_debug_regs(vcpu);
- for (i = 0; i < KVM_NR_DB_REGS; i++)
- vcpu->arch.eff_db[i] = vcpu->arch.db[i];
+ kvm_update_dr0123(vcpu);
+ kvm_update_dr6(vcpu);
+ kvm_update_dr7(vcpu);
+ vcpu->arch.switch_db_regs &= ~KVM_DEBUGREG_RELOAD;
}
/*