Re: [Xen-devel] [PATCH] VMX: fix/adjust trap injection

["Tian, Kevin" <kevin.tian@xxxxxxxxx>]

> From: Jan Beulich [mailto:JBeulich@xxxxxxxx]
> Sent: Monday, November 23, 2015 8:49 PM
> 
> In the course of investigating the 4.1.6 backport issue of the XSA-156
> patch I realized that #DB injection has always been broken, but with it
> now getting always intercepted the problem has got worse: Documentation
> clearly states that neither DR7.GD nor DebugCtl.LBR get cleared before
> the intercept, so this is something we need to do before reflecting the
> intercepted exception.
> 
> While adjusting this (and also with 4.1.6's strange use of
> X86_EVENTTYPE_SW_EXCEPTION for #DB in mind) I further realized that
> the special casing of individual vectors shouldn't be done for
> software interrupts (resulting from INT $nn).
> 
> And then some code movement: Setting of CR2 for #PF can be done in the
> same switch() statement (no need for a separate if()), and reading of
> intr_info is better done close the the consumption of the variable
> (allowing the compiler to generate better code / use fewer registers
> for variables).
> 
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
> 

Acked-by: Kevin Tian <kevin.tian@xxxxxxxxx>

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