> -----Original Message-----
> From: Jonathan Cameron <jonathan.came...@huawei.com>
> Sent: Wednesday, May 8, 2024 12:31 AM
> To: Yao, Xingtao/姚 幸涛 <yaoxt.f...@fujitsu.com>
> Cc: fan...@samsung.com; qemu-devel@nongnu.org
> Subject: Re: [PATCH v2] mem/cxl_type3: support 3, 6, 12 and 16 interleave ways
>
> On Tue, 7 May 2024 00:22:00 +0000
> "Xingtao Yao (Fujitsu)" <yaoxt.f...@fujitsu.com> wrote:
>
> > > -----Original Message-----
> > > From: Jonathan Cameron <jonathan.came...@huawei.com>
> > > Sent: Tuesday, April 30, 2024 10:43 PM
> > > To: Yao, Xingtao/姚 幸涛 <yaoxt.f...@fujitsu.com>
> > > Cc: fan...@samsung.com; qemu-devel@nongnu.org
> > > Subject: Re: [PATCH v2] mem/cxl_type3: support 3, 6, 12 and 16 interleave
> ways
> > >
> > > On Wed, 24 Apr 2024 01:36:56 +0000
> > > "Xingtao Yao (Fujitsu)" <yaoxt.f...@fujitsu.com> wrote:
> > >
> > > > ping.
> > > >
> > > > > -----Original Message-----
> > > > > From: Yao Xingtao <yaoxt.f...@fujitsu.com>
> > > > > Sent: Sunday, April 7, 2024 11:07 AM
> > > > > To: jonathan.came...@huawei.com; fan...@samsung.com
> > > > > Cc: qemu-devel@nongnu.org; Yao, Xingtao/姚 幸涛
> > > <yaoxt.f...@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.f...@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.
> >
> > according to the CXL specifications (8.2.4.20.1 CXL HDM Decoder Capability
> Register (Offset 00h)),
> > this feature is only applicable to cxl.mem, upstream switch port and CXL
> > host
> bridges shall hardwrite
> > these bits to 0.
> >
> > so I think it would be more appropriate to set these bits here.
> I don't follow. hdm_init_common() (sorry wrong function name above)
> has some type specific stuff already to show how this can be done.
> I'd prefer to minimize what we set directly in the ct3d_reset() call
> because it loses the connection to the rest of the register setup.
thanks, got it.
>
> Jonathan
>
>
>
> Jonathan
>
>
> >
> > >
> > > > > cxl_device_register_init_t3(ct3d);
> > > > >
> > > > > /*
> > > > > --
> > > > > 2.37.3
> > > >
> >
