Re: [Xen-devel] [XEN PATCH v2] x86/vm_event: add short-circuit for breakpoints (aka, "fast single step")

[Jan Beulich <jbeulich@xxxxxxxx>]

On 18.12.2019 12:34, Sergey Kovalev wrote:
> On 18.12.2019 13:55, Jan Beulich wrote:
>> On 18.12.2019 06:53, Sergey Kovalev wrote:
>>> --- a/xen/arch/x86/hvm/hvm.c
>>> +++ b/xen/arch/x86/hvm/hvm.c
>>> @@ -5126,6 +5126,18 @@ void hvm_toggle_singlestep(struct vcpu *v)
>>>        v->arch.hvm.single_step = !v->arch.hvm.single_step;
>>>    }
>>>
>>> +void hvm_fast_singlestep(struct vcpu *v, uint16_t p2midx)
>>> +{
>>> +    ASSERT(atomic_read(&v->pause_count));
>>> +
>>> +    if ( !hvm_is_singlestep_supported() )
>>> +        return;
>>> +
>>> +    v->arch.hvm.single_step = true;
>>> +    v->arch.hvm.fast_single_step.enabled = true;
>>> +    v->arch.hvm.fast_single_step.p2midx = p2midx;
>>
>> Perhaps better at least range check p2midx before storing?
> What is the valid range?

The size of the array you use it to index into.

>> Also your patch has come through mangled, reminding me of a problem
>> I had with Thunderbird after initially having switched to it. There
>> are line length / wrapping settings you may need to play with to
>> avoid it inserting extra blanks (I'm sorry, I don't really recall
>> which one(s) it was.).
> Thank You! I used Thunderbird too :) I will re-check it.
> Though I have setup line wrap at 300.

I think you want it set to zero.

Jan

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