Re: [Xen-devel] [PATCH 11/19] xen: arm: Annotate handlers for PCTR_EL2.Tx

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

On Mon, 2015-04-06 at 13:18 +0200, Julien Grall wrote:
> Hi Ian,
> 
> Subject: s/PCTR/CPTR/
> 
> On 31/03/2015 12:07, Ian Campbell wrote:
> > Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
> > ---
> >   xen/arch/arm/traps.c |   14 ++++++++++++++
> >   1 file changed, 14 insertions(+)
> >
> > diff --git a/xen/arch/arm/traps.c b/xen/arch/arm/traps.c
> > index 9cdbda8..ba120e5 100644
> > --- a/xen/arch/arm/traps.c
> > +++ b/xen/arch/arm/traps.c
> > @@ -1704,6 +1704,11 @@ static void do_cp15_32(struct cpu_user_regs *regs,
> >        * ARMv7 (DDI 0406C.b): B1.14.3
> >        * ARMv8 (DDI 0487A.d): D1-1501 Table D1-43
> >        *
> > +     * CPTR_EL2.T{0..9,12..13}
> > +     *
> > +     * ARMv7 (DDI 0406C.b): B1.14.12
> > +     * ARMv8 (DDI 0487A.d): N/A
> 
> I would also update the comment on top of WRITE_SYSREG(..., CPTR_EL2) to 
> make clear that CP0..CP9 & CP12..CP13 are only traps for ARMv7.

On v8 the corresponding bits are RES1, i.e. they always trap. I wrote:

    /* Trap all coprocessor registers (0-13) except cp10 and
     * cp11 for VFP.
     *
     * /!\ All coprocessors except cp10 and cp11 cannot be used in Xen.
     *
     * On ARM64 the TCPx bits which we set here (0..9,12,13) are all
     * RES1, i.e. they would trap whether we did this write or not.
     */

Ian.


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