On Thu, 28 Dec 2023 at 00:42, Richard Henderson
<richard.hender...@linaro.org> wrote:
>
> On 12/18/23 22:32, Peter Maydell wrote:
> > Mark up the cpreginfo structs to indicate offsets for system
> > registers from VNCR_EL2, as defined in table D8-66 in rule R_CSRPQ in
> > the Arm ARM. This commit covers offsets 0x100 to 0x160.
> >
> > Many (but not all) of the registers in this range have _EL12 aliases,
> > and the slot in memory is shared between the _EL12 version of the
> > register and the _EL1 version. Where we programmatically generate
> > the regdef for the _EL12 register, arrange that its
> > nv2_redirect_offset is set up correctly to do this.
> >
> > Signed-off-by: Peter Maydell <peter.mayd...@linaro.org>
> > ---
> > target/arm/debug_helper.c | 1 +
> > target/arm/helper.c | 22 ++++++++++++++++++++++
> > 2 files changed, 23 insertions(+)
>
> Reviewed-by: Richard Henderson <richard.hender...@linaro.org>
>
> > + /*
> > + * If the _EL1 register is redirected to memory by FEAT_NV2,
> > + * then it shares the offset with the _EL12 register,
> > + * and which one is redirected depends on HCR_EL2.NV1.
> > + */
> > + if (new_reg->nv2_redirect_offset) {
> > + assert(new_reg->nv2_redirect_offset & NV2_REDIR_NV1);
> > + new_reg->nv2_redirect_offset &= ~NV2_REDIR_NV1;
> > + new_reg->nv2_redirect_offset |= NV2_REDIR_NO_NV1;
> > + }
>
> Could use xor to flip both bits at once.
Could do, but explicit clear-then-set seems a bit more
readable to me, and since this is only happening once at
startup there's no efficiency concern here.
thanks
-- PMM
