From mboxrd@z Thu Jan  1 00:00:00 1970
From: bugzilla-daemon@bugzilla.kernel.org
Subject: [Bug 65561] KVM:Entry failed on Single stepping sti instruction
Date: Sat, 24 May 2014 05:51:08 +0000
Message-ID: <bug-65561-28872-j6zPd1wFbP@https.bugzilla.kernel.org/>
References: <bug-65561-28872@https.bugzilla.kernel.org/>
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https://bugzilla.kernel.org/show_bug.cgi?id=65561

--- Comment #23 from Jidong Xiao <jidong.xiao@gmail.com> ---
Jatin, do you mean that if one instruction triggers a VM_EXIT, then it won't
trigger the emulate code? So why the emulate code tries to emulate those
privileged instructions, like wrmsr, rdmsr, mov cr to reg, mov dr to reg, I
think these instructions will trigger VM_EXIT anyway, but we see the kvm
emulator still attempt to emulate them.
(In reply to Jatin Kumar from comment #21)
> The way I would approach this problem is to first check if there is a
> VM_EXIT while executing this instruction. You should be able to find that in
> vmx_vcpu_run() function (I guess in KVM code). Put a printk there and print
> the instruction as well which caused VM_EXIT.
> 
> Futher you should try to investigate if the control flow is trying to
> emulate this instruction and then your printk's should be triggered.
> 
> CAUTION: I haven't spent much time digging KVM code, but I am confident
> about the VM_EXIT part. Still after putting in some effort, you may want to
> wait for Paolo's reply :)

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