Re: [PATCH v2] mem/cxl_type3: support 3, 6, 12 and 16 interleave ways

[Jonathan Cameron via <qemu-devel@nongnu.org>]

On Wed, 24 Apr 2024 01:36:56 +0000
"Xingtao Yao (Fujitsu)" <yaoxt.fnst@fujitsu.com> wrote:

> ping.
> 
> > -----Original Message-----
> > From: Yao Xingtao <yaoxt.fnst@fujitsu.com>
> > Sent: Sunday, April 7, 2024 11:07 AM
> > To: jonathan.cameron@huawei.com; fan.ni@samsung.com
> > Cc: qemu-devel@nongnu.org; Yao, Xingtao/姚 幸涛 <yaoxt.fnst@fujitsu.com>
> > Subject: [PATCH v2] mem/cxl_type3: support 3, 6, 12 and 16 interleave ways
> > 
> > Since the kernel does not check the interleave capability, a
> > 3-way, 6-way, 12-way or 16-way region can be create normally.
> > 
> > Applications can access the memory of 16-way region normally because
> > qemu can convert hpa to dpa correctly for the power of 2 interleave
> > ways, after kernel implementing the check, this kind of region will
> > not be created any more.
> > 
> > For non power of 2 interleave ways, applications could not access the
> > memory normally and may occur some unexpected behaviors, such as
> > segmentation fault.
> > 
> > So implements this feature is needed.
> > 
> > Link:
> > https://lore.kernel.org/linux-cxl/3e84b919-7631-d1db-3e1d-33000f3f3868@fujits
> > u.com/
> > Signed-off-by: Yao Xingtao <yaoxt.fnst@fujitsu.com>
> > ---
> >  hw/mem/cxl_type3.c | 18 ++++++++++++++----
> >  1 file changed, 14 insertions(+), 4 deletions(-)
> > 
> > diff --git a/hw/mem/cxl_type3.c b/hw/mem/cxl_type3.c
> > index b0a7e9f11b..d6ef784e96 100644
> > --- a/hw/mem/cxl_type3.c
> > +++ b/hw/mem/cxl_type3.c
> > @@ -805,10 +805,17 @@ static bool cxl_type3_dpa(CXLType3Dev *ct3d, hwaddr
> > host_addr, uint64_t *dpa)
> >              continue;
> >          }
> > 
> > -        *dpa = dpa_base +
> > -            ((MAKE_64BIT_MASK(0, 8 + ig) & hpa_offset) |
> > -             ((MAKE_64BIT_MASK(8 + ig + iw, 64 - 8 - ig - iw) & hpa_offset)  
> > -              >> iw));  
> > +        if (iw < 8) {
> > +            *dpa = dpa_base +
> > +                ((MAKE_64BIT_MASK(0, 8 + ig) & hpa_offset) |
> > +                 ((MAKE_64BIT_MASK(8 + ig + iw, 64 - 8 - ig - iw) & hpa_offset)
> > +                  >> iw));
> > +        } else {
> > +            *dpa = dpa_base +
> > +                ((MAKE_64BIT_MASK(0, 8 + ig) & hpa_offset) |
> > +                 ((((MAKE_64BIT_MASK(ig + iw, 64 - ig - iw) & hpa_offset)
> > +                   >> (ig + iw)) / 3) << (ig + 8)));
> > +        }
> > 
> >          return true;
> >      }
> > @@ -906,6 +913,9 @@ static void ct3d_reset(DeviceState *dev)
> >      uint32_t *write_msk = ct3d->cxl_cstate.crb.cache_mem_regs_write_mask;
> > 
> >      cxl_component_register_init_common(reg_state, write_msk,
> > CXL2_TYPE3_DEVICE);
> > +    ARRAY_FIELD_DP32(reg_state, CXL_HDM_DECODER_CAPABILITY,
> > 3_6_12_WAY, 1);
> > +    ARRAY_FIELD_DP32(reg_state, CXL_HDM_DECODER_CAPABILITY,
> > 16_WAY, 1);
> > +

Why here rather than in hdm_reg_init_common()?
It's constant data and is currently being set to 0 in there.

> >      cxl_device_register_init_t3(ct3d);
> > 
> >      /*
> > --
> > 2.37.3  
>