Re: [PATCH v3 4/4] arm_mpam: Update architecture version check for MPAM MSC

[Zeng Heng]

Hi all,

On 2026/5/9 0:35, Ben Horgan wrote:
> Hi James,
>
> On 5/8/26 17:23, James Morse wrote:
> > From: Zeng Heng <zengheng4@xxxxxxxxxx>
> >
> > In addition to updating the CPU MPAM version check, the MPAM MSC version
> > check also need to be updated. mpam_msc_check_aidr() is added to check
> > the MSC AIDR register, ensuring that both the major and minor version
> > numbers fall within the supported range of the MPAM architecture version.
> >
> > Signed-off-by: Zeng Heng <zengheng4@xxxxxxxxxx>
> > [ morse: changed mpam_msc_check_aidr() to accept versions like v1.2 ]
> > Signed-off-by: James Morse <james.morse@xxxxxxx>
> > ---
> >   drivers/resctrl/mpam_devices.c | 23 ++++++++++++++++++++---
> >   1 file changed, 20 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/mpam_devices.c
> > index 916d8fd45ed5..1771e9712ca2 100644
> > --- a/drivers/resctrl/mpam_devices.c
> > +++ b/drivers/resctrl/mpam_devices.c
> > @@ -224,6 +224,24 @@ static inline void _mpam_write_monsel_reg(struct mpam_msc *msc, u16 reg, u32 val
> >   
> >   #define mpam_write_monsel_reg(msc, reg, val)   _mpam_write_monsel_reg(msc, MSMON_##reg, val)
> >   
> > +static bool mpam_msc_check_aidr(struct mpam_msc *msc)
> > +{
> > +	u32 aidr = __mpam_read_reg(msc, MPAMF_AIDR);
> > +	u32 major = FIELD_GET(MPAMF_AIDR_ARCH_MAJOR_REV, aidr);
> > +	u32 minor = FIELD_GET(MPAMF_AIDR_ARCH_MINOR_REV, aidr);
> > +
> > +	/*
> > +	 * v0.0 and >v2.x aren't supported, but anything else should be backward
> > +	 * compatible to v0.1 or v1.0.
> > +	 */
> > +	if (!major && !minor)
> > +		return false;
> > +	if (major > 1) >> +		return false;

Would it make sense to introduce a new macro that defines the maximum
supported major version?

~~~
#define MPAM_ARCH_MAJOR_VERSION_MAX    0x1

if (major > MPAM_ARCH_MAJOR_VERSION_MAX)
	return false;
~~~


Best regards,
Zeng Heng

> > +
> > +	return true;
> > +}
> > +
> >   static u64 mpam_msc_read_idr(struct mpam_msc *msc)
> >   {
> >   	u64 idr_high = 0, idr_low;
> > @@ -951,9 +969,8 @@ static int mpam_msc_hw_probe(struct mpam_msc *msc)
> >   
> >   	lockdep_assert_held(&msc->probe_lock);
> >   
> > -	idr = __mpam_read_reg(msc, MPAMF_AIDR);
> > -	if ((idr & MPAMF_AIDR_ARCH_MAJOR_REV) != MPAM_ARCHITECTURE_V1) { >
> nit: MPAM_ARCHITECTURE_V1 is now unused.
>
> Reviewed-by: Ben Horgan <ben.horgan@xxxxxxx>