[PATCH] Revert "KVM: x86: fix missed hardware breakpoints"

[Paolo Bonzini <pbonzini@redhat.com>]

[fix for patches applied in the wrong order to 4.1.y and 4.4.y
 ---
 the change is part of 70e4da7a8ff62f2775337b705f45c804bb450454, which
 is already in stable kernels 4.1.y to 4.4.y.  this part of the fix
 however was later undone, so remove the line again]

The following patches were applied in the wrong order in -stable. This
is the order as they appear in Linus' tree,

 [0] commit 4e422bdd2f84 ("KVM: x86: fix missed hardware breakpoints")
 [1] commit 172b2386ed16 ("KVM: x86: fix missed hardware breakpoints")
 [2] commit 70e4da7a8ff6 ("KVM: x86: fix root cause for missed hardware breakpoints")

but this is the order for linux-4.4.y

 [1] commit fc90441e728a ("KVM: x86: fix missed hardware breakpoints")
 [2] commit 25e8618619a5 ("KVM: x86: fix root cause for missed hardware breakpoints")
 [0] commit 0f6e5e26e68f ("KVM: x86: fix missed hardware breakpoints")

The upshot is that KVM_DEBUGREG_RELOAD is always set when returning
from kvm_arch_vcpu_load() in stable, but not in Linus' tree.

This happened because [0] and [1] are the same patch.  [0] and [1] come from two
different merges, and the later merge is trivially resolved; when [2]
is applied it reverts both of them.  Instead, when using the [1][2][0]
order, patches applies normally but "KVM: x86: fix missed hardware
breakpoints" is present in the final tree.

Cc: stable kernels <stable@vger.kernel.org>     # 4.1, 4.4
Reported-by: Matt Fleming <matt@codeblueprint.co.uk>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 arch/x86/kvm/x86.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 4244c2baf57d..f4891f2ece23 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2752,7 +2752,6 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
 	}
 
 	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)
-- 
2.7.4