Hi Julien,
> -----Original Message-----
> From: Julien Grall <jul...@xen.org>
> Sent: 2020年8月25日 19:18
> To: Wei Chen <wei.c...@arm.com>; xen-devel@lists.xenproject.org;
> sstabell...@kernel.org
> Cc: Andre Przywara <andre.przyw...@arm.com>; Bertrand Marquis
> <bertrand.marq...@arm.com>; Penny Zheng <penny.zh...@arm.com>; Kaly
> Xin <kaly....@arm.com>; nd <n...@arm.com>
> Subject: Re: [PATCH v3 2/2] xen/arm: Throw messages for unknown FP/SIMD
> implement ID
>
> Hi,
>
> On 25/08/2020 11:08, Wei Chen wrote:
> > Arm ID_AA64PFR0_EL1 register provides two fields to describe CPU
> > FP/SIMD implementations. Currently, we exactly know the meaning of
> > 0x0, 0x1 and 0xf of these fields. Xen treats value < 8 as FP/SIMD
> > features presented. If there is a value 0x2 bumped in the future,
> > Xen behaviors for value <= 0x1 can also take effect. But what Xen
> > done for value <= 0x1 may not always cover new value 0x2 required.
> > We throw these messages to break the silence when Xen detected
> > unknown FP/SIMD IDs to notice user to check.
> >
> > Signed-off-by: Wei Chen <wei.c...@arm.com>
> > Reviewed-by: Bertrand Marquis <bertrand.marq...@arm.com>
>
> OOI, is this reviewed-by coming from internal review?
Ahh. No, I remember Bertrand gave me a reviewed-by in v2, so I picked it.
I had left OSS for a while, and forgot something. If I can't pick it directly,
could
you please tell me how can I handle such reviewed-by?
>
> > ---
> > xen/arch/arm/setup.c | 12 ++++++++++++
> > xen/include/asm-arm/cpufeature.h | 2 ++
> > 2 files changed, 14 insertions(+)
> >
> > diff --git a/xen/arch/arm/setup.c b/xen/arch/arm/setup.c
> > index 7968cee47d..ef39ce1ec6 100644
> > --- a/xen/arch/arm/setup.c
> > +++ b/xen/arch/arm/setup.c
> > @@ -133,6 +133,18 @@ static void __init processor_id(void)
> > cpu_has_simd ? " AdvancedSIMD" : "",
> > cpu_has_gicv3 ? " GICv3-SysReg" : "");
> >
> > + /* Warn user if we find unknown floating-point features */
> > + if ( cpu_has_unknown_fp )
> > + printk(XENLOG_WARNING "WARNING: Unknown Floating-point ID:%d, "
> > + "this may result to corruption on the platform\n",
> > + boot_cpu_feature64(fp));
> > +
> > + /* Warn user if we find unknown AdvancedSIMD features */
> > + if ( cpu_has_unknown_simd )
> > + printk(XENLOG_WARNING "WARNING: Unknown AdvancedSIMD ID:%d,
> "
> > + "this may result to corruption on the platform\n",
> > + boot_cpu_feature64(simd));
> > +
> > printk(" Debug Features: %016"PRIx64" %016"PRIx64"\n",
> > boot_cpu_data.dbg64.bits[0], boot_cpu_data.dbg64.bits[1]);
> > printk(" Auxiliary Features: %016"PRIx64" %016"PRIx64"\n",
> > diff --git a/xen/include/asm-arm/cpufeature.h b/xen/include/asm-
> arm/cpufeature.h
> > index 10878ead8a..a32309986e 100644
> > --- a/xen/include/asm-arm/cpufeature.h
> > +++ b/xen/include/asm-arm/cpufeature.h
> > @@ -16,6 +16,8 @@
> > #define cpu_has_fp (boot_cpu_feature64(fp) < 8)
> > #define cpu_has_simd (boot_cpu_feature64(simd) < 8)
> > #define cpu_has_gicv3 (boot_cpu_feature64(gic) == 1)
> > +#define cpu_has_unknown_fp (cpu_has_fp && (boot_cpu_feature64(fp) >=
> 2))
> > +#define cpu_has_unknown_simd (cpu_has_simd &&
> (boot_cpu_feature64(simd) >= 2))
>
> I would rather prefer if we don't introduce cpu_has_unknown_{fp, simd}
> but open-code directly in the 'if'.
>
> Other than that the code looks ok to me.
Thanks, I could address it in v4.
>
> Cheers,
>
> --
> Julien Grall
