Re: [PATCH v3 04/23] arm64: Move MAIR_EL1_SET to asm/memory.h

David Brazdil
2020-12-01T13:59:58Z

Hey Mark,

> > diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h
> > index cd61239bae8c..54a22cb5b17b 100644
> > --- a/arch/arm64/include/asm/memory.h
> > +++ b/arch/arm64/include/asm/memory.h
> > @@ -152,6 +152,19 @@
> > #define MT_S2_FWB_NORMAL 6
> > #define MT_S2_FWB_DEVICE_nGnRE 1
> >
> > +/*
> > + * Default MAIR_ELx. MT_NORMAL_TAGGED is initially mapped as Normal memory and
> > + * changed during __cpu_setup to Normal Tagged if the system supports MTE.
> > + */
> > +#define MAIR_ELx_SET \
> > + (MAIR_ATTRIDX(MAIR_ATTR_DEVICE_nGnRnE, MT_DEVICE_nGnRnE) | \
> > + MAIR_ATTRIDX(MAIR_ATTR_DEVICE_nGnRE, MT_DEVICE_nGnRE) | \
> > + MAIR_ATTRIDX(MAIR_ATTR_DEVICE_GRE, MT_DEVICE_GRE) | \
> > + MAIR_ATTRIDX(MAIR_ATTR_NORMAL_NC, MT_NORMAL_NC) | \
> > + MAIR_ATTRIDX(MAIR_ATTR_NORMAL, MT_NORMAL) | \
> > + MAIR_ATTRIDX(MAIR_ATTR_NORMAL_WT, MT_NORMAL_WT) | \
> > + MAIR_ATTRIDX(MAIR_ATTR_NORMAL, MT_NORMAL_TAGGED))
>
> Patch 7 initializes MAIR_EL2 with this directly rather than copying it
> from MAIR_EL1, which means that MT_NORMAL_TAGGED will never be tagged
> within the nVHE hyp code.
>
> Is that expected? I suspect it's worth a comment here (introduced in
> patch 7), just to make that clear.

Ouch, that didn't use to be there. In that case let's not build more implicit
assumptions into the code. I'll pass MAIR_EL1 in kvm_nvhe_init_params.

David