Re: [PATCH 4/7] KVM: arm64: guest debug, add SW break point support

[Christoffer Dall]

On Wed, Nov 26, 2014 at 05:07:20PM +0100, Andrew Jones wrote:
> On Tue, Nov 25, 2014 at 04:10:02PM +0000, Alex Bennée wrote:
> > This adds support for SW breakpoints inserted by userspace.
> > 
> > First we need to trap all BKPT exceptions in the hypervisor (ELS). This
> > in controlled through the MDCR_EL2 register. I've added a new field to
> > the vcpu structure to hold this value. There should be scope to
> > rationlise this with the VCPU_DEBUG_FLAGS/KVM_ARM64_DEBUG_DIRTY_SHIFT
> > manipulation in later patches.
> 
> I think we should start using the new mdcr_el2 field everywhere we plan
> to within the same series that it is introduced. Otherwise it's hard
> to tell if we need an mdcr_el2 field, or if a more generic field would
> suffice. We can always translate bits of a more generic field to
> mdcr_el2 bits when necessary, but not the reverse.
> 
Agreed, this is getting messy already with this patch.

-Christoffer
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