Re: [PATCH 2/7] KVM: x86: Function for determining exception type

[Nadav Amit]

Few comments to see we are on the same page:

On 7/21/14, 3:18 PM, Paolo Bonzini wrote:
> Il 21/07/2014 13:37, Nadav Amit ha scritto:
> > +int kvm_exception_type(unsigned int nr)
>
> The manual calls this the exception class.
Yes, but it also calls it exception "type" (see table 6-1 
"Protected-Mode Exceptions and Interrupts" on the SDM).
I called it exception type, since there is a function exception_class 
that is used to handle nested exceptions.

> > +	case VE_VECTOR:
> > +		return EXCPT_FAULT;
> > +	case DB_VECTOR:
> > +		return EXCPT_FAULT_OR_TRAP;
>
> It is only a fault for instruction fetch breakpoints.  You can modify
> kvm_vcpu_check_breakpoint to set RF, add a comment here that fault
> handling is done elsewhere, and return EXCPT_TRAP.
Unless I am mistaken, kvm_vcpu_check_breakpoint checks only for 
instruction breakpoint. Since instruction breakpoint should not cause RF 
to be set, this function should not be changed.

Anyhow, I would return EXCPT_TRAP on DB_VECTOR.

Nadav

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/