linux-kernel - Re: [PATCH] KVM: x86: fix root cause for missed hardware breakpoints

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Date:	Fri, 26 Feb 2016 13:48:47 +0100
From:	Paolo Bonzini <pbonzini@...hat.com>
To:	Nadav Amit <nadav.amit@...il.com>
Cc:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	kvm <kvm@...r.kernel.org>, stable@...r.kernel.org,
	Nadav Amit <namit@...technion.ac.il>,
	Andrey Wagin <avagin@...il.com>,
	Xiao Guangrong <guangrong.xiao@...ux.intel.com>
Subject: Re: [PATCH] KVM: x86: fix root cause for missed hardware breakpoints



On 26/02/2016 13:14, Nadav Amit wrote:
> Seems correct. The code may be easier to follow if the following line:
> 
> vcpu->arch.switch_db_regs &= ~KVM_DEBUGREG_WONT_EXIT
> 
> would have been moved out of svm_sync_dirty_debug_regs and
> vmx_sync_dirty_debug_regs into the flow of vcpu_enter_guest (above).

It is there because removing the bit is tied to actually enabling debug
register exits.  On one hand it's bad to have duplicated code, on the
other hand there's a reason for it...  I'm a bit undecided on whether to
move that duplicated line to x86.c.

Paolo