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From: Matt Fleming <matt@codeblueprint.co.uk>
To: Greg KH <gregkh@linuxfoundation.org>,
	Paolo Bonzini <pbonzini@redhat.com>
Cc: linux-kernel@vger.kernel.org
Subject: KVM patches applied in weird order in -stable
Date: Tue, 13 Sep 2016 15:51:00 +0100	[thread overview]
Message-ID: <20160913145100.GK3872@codeblueprint.co.uk> (raw)

Folks,

While hunting down a performance issue involving KVM I was surprised
to see "native_set_debugreg()" as the first entry in `perf top`.

Digging deeper, it looks as though 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.

             reply	other threads:[~2016-09-13 14:51 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-09-13 14:51 Matt Fleming [this message]
2016-09-13 14:58 ` KVM patches applied in weird order in -stable Greg KH
2016-09-13 16:26   ` Paolo Bonzini
2016-09-13 16:57     ` Greg KH
2016-09-13 16:58       ` Paolo Bonzini
2016-09-14  1:19         ` Greg KH

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