Re: [PATCH] When switching to a vm8086 task, load segments as 16-bit

[Avi Kivity <avi@redhat.com>]

On 08/11/2009 07:45 PM, Anthony Liguori wrote:
> Avi Kivity wrote:
>> On 08/11/2009 04:00 AM, Anthony Liguori wrote:
>>
>> kvm_load_segment_descriptor() can already load plain segments:
>>
>>     if (!(vcpu->arch.cr0 & X86_CR0_PE))
>>         return kvm_load_realmode_segment(vcpu, selector, seg);
>>
>> so we can simplify the patch a bit by extending the check.
>
> I went down that road but you need to check the to-be-switched-into 
> tss, which isn't available directly from vcpu so we would have to 
> either pass the tss as a parameter to the function or at least a flag 
> indicating that we're going into vm8086 mode.
>

eflags is already updated at this point, so no need for an additional 
parameter.

> There are other callers of kvm_load_segment_descriptor that would need 
> updating and it already takes a few extra parameters.  That's why I 
> went down this road.

The other callers are a good reason to do it in 
kvm_load_segment_descriptor(), so they don't have to perform the check 
themselves.  In fact with this change your patch will fix a few more bugs.

-- 
error compiling committee.c: too many arguments to function