Patchwork [3.8.y.z,extended,stable] Patch "KVM: VMX: fix halt emulation while emulating invalid guest sate" has been added to staging queue

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Submitter Kamal Mostafa
Date May 22, 2013, 9:55 p.m.
Message ID <1369259726-25132-1-git-send-email-kamal@canonical.com>
Download mbox | patch
Permalink /patch/245740/
State New
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Kamal Mostafa - May 22, 2013, 9:55 p.m.
This is a note to let you know that I have just added a patch titled

    KVM: VMX: fix halt emulation while emulating invalid guest sate

to the linux-3.8.y-queue branch of the 3.8.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.8.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.8.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

From ea89e81bf579685a95fe16717ed9fec0e5457f34 Mon Sep 17 00:00:00 2001
From: Gleb Natapov <gleb@redhat.com>
Date: Wed, 8 May 2013 18:38:44 +0300
Subject: KVM: VMX: fix halt emulation while emulating invalid guest sate

commit 8d76c49e9ffeee839bc0b7a3278a23f99101263e upstream.

The invalid guest state emulation loop does not check halt_request
which causes 100% cpu loop while guest is in halt and in invalid
state, but more serious issue is that this leaves halt_request set, so
random instruction emulated by vm86 #GP exit can be interpreted
as halt which causes guest hang. Fix both problems by handling
halt_request in emulation loop.

Reported-by: Tomas Papan <tomas.papan@gmail.com>
Tested-by: Tomas Papan <tomas.papan@gmail.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
---
 arch/x86/kvm/vmx.c | 6 ++++++
 1 file changed, 6 insertions(+)

--
1.8.1.2

Patch

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 9120ae1..1b29ec6 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -5059,6 +5059,12 @@  static int handle_invalid_guest_state(struct kvm_vcpu *vcpu)
 			return 0;
 		}

+		if (vcpu->arch.halt_request) {
+			vcpu->arch.halt_request = 0;
+			ret = kvm_emulate_halt(vcpu);
+			goto out;
+		}
+
 		if (signal_pending(current))
 			goto out;
 		if (need_resched())