Re: [PATCH v3 2/2] hw/cxl: Multi-Region CXL Type-3 Devices (Volatile and Persistent)

["Philippe Mathieu-Daudé" <philmd@linaro.org>]

On 21/2/23 15:00, Jonathan Cameron wrote:
> From: Gregory Price <gourry.memverge@gmail.com>
> 
> This commit enables each CXL Type-3 device to contain one volatile
> memory region and one persistent region.
> 
> Two new properties have been added to cxl-type3 device initialization:
>      [volatile-memdev] and [persistent-memdev]
> 
> The existing [memdev] property has been deprecated and will default the
> memory region to a persistent memory region (although a user may assign
> the region to a ram or file backed region). It cannot be used in
> combination with the new [persistent-memdev] property.
> 
> Partitioning volatile memory from persistent memory is not yet supported.
> 
> Volatile memory is mapped at DPA(0x0), while Persistent memory is mapped
> at DPA(vmem->size), per CXL Spec 8.2.9.8.2.0 - Get Partition Info.
> 
> Signed-off-by: Gregory Price <gregory.price@memverge.com>
> Reviewed-by: Davidlohr Bueso <dave@stgolabs.net>
> Reviewed-by: Fan Ni <fan.ni@samsung.com>
> Tested-by: Fan Ni <fan.ni@samsung.com>
> Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> 
> ---
> v3:
> - Don't set the DVSEC range register base address
> v2:
> - Fixed an off by one in address space selection.
> - Gather tags.
> ---
>   docs/system/devices/cxl.rst    |  49 ++++--
>   hw/cxl/cxl-mailbox-utils.c     |  26 +--
>   hw/mem/cxl_type3.c             | 294 +++++++++++++++++++++++++--------
>   include/hw/cxl/cxl_device.h    |  11 +-
>   tests/qtest/bios-tables-test.c |   8 +-
>   tests/qtest/cxl-test.c         |  76 +++++++--
>   6 files changed, 353 insertions(+), 111 deletions(-)
> 
> diff --git a/docs/system/devices/cxl.rst b/docs/system/devices/cxl.rst
> index f25783a4ec..89a41cff73 100644
> --- a/docs/system/devices/cxl.rst
> +++ b/docs/system/devices/cxl.rst
> @@ -300,7 +300,7 @@ Example topology involving a switch::
>   
>   Example command lines
>   ---------------------
> -A very simple setup with just one directly attached CXL Type 3 device::
> +A very simple setup with just one directly attached CXL Type 3 Persistent Memory device::
>   
>     qemu-system-aarch64 -M virt,gic-version=3,cxl=on -m 4g,maxmem=8G,slots=8 -cpu max \
>     ...
> @@ -308,7 +308,28 @@ A very simple setup with just one directly attached CXL Type 3 device::
>     -object memory-backend-file,id=cxl-lsa1,share=on,mem-path=/tmp/lsa.raw,size=256M \
>     -device pxb-cxl,bus_nr=12,bus=pcie.0,id=cxl.1 \
>     -device cxl-rp,port=0,bus=cxl.1,id=root_port13,chassis=0,slot=2 \
> -  -device cxl-type3,bus=root_port13,memdev=cxl-mem1,lsa=cxl-lsa1,id=cxl-pmem0 \
> +  -device cxl-type3,bus=root_port13,persistent-memdev=cxl-mem1,lsa=cxl-lsa1,id=cxl-pmem0 \
> +  -M cxl-fmw.0.targets.0=cxl.1,cxl-fmw.0.size=4G
> +
> +A very simple setup with just one directly attached CXL Type 3 Volatile Memory device::
> +
> +  qemu-system-aarch64 -M virt,gic-version=3,cxl=on -m 4g,maxmem=8G,slots=8 -cpu max \
> +  ...
> +  -object memory-backend-ram,id=vmem0,share=on,size=256M \
> +  -device pxb-cxl,bus_nr=12,bus=pcie.0,id=cxl.1 \
> +  -device cxl-rp,port=0,bus=cxl.1,id=root_port13,chassis=0,slot=2 \
> +  -device cxl-type3,bus=root_port13,volatile-memdev=vmem0,id=cxl-vmem0 \
> +  -M cxl-fmw.0.targets.0=cxl.1,cxl-fmw.0.size=4G
> +
> +The same volatile setup may optionally include an LSA region::
> +
> +  qemu-system-aarch64 -M virt,gic-version=3,cxl=on -m 4g,maxmem=8G,slots=8 -cpu max \
> +  ...
> +  -object memory-backend-ram,id=vmem0,share=on,size=256M \
> +  -object memory-backend-file,id=cxl-lsa0,share=on,mem-path=/tmp/lsa.raw,size=256M \
> +  -device pxb-cxl,bus_nr=12,bus=pcie.0,id=cxl.1 \
> +  -device cxl-rp,port=0,bus=cxl.1,id=root_port13,chassis=0,slot=2 \
> +  -device cxl-type3,bus=root_port13,volatile-memdev=vmem0,lsa=cxl-lsa0,id=cxl-vmem0 \
>     -M cxl-fmw.0.targets.0=cxl.1,cxl-fmw.0.size=4G
>   
>   A setup suitable for 4 way interleave. Only one fixed window provided, to enable 2 way
> @@ -328,13 +349,13 @@ the CXL Type3 device directly attached (no switches).::
>     -device pxb-cxl,bus_nr=12,bus=pcie.0,id=cxl.1 \
>     -device pxb-cxl,bus_nr=222,bus=pcie.0,id=cxl.2 \
>     -device cxl-rp,port=0,bus=cxl.1,id=root_port13,chassis=0,slot=2 \
> -  -device cxl-type3,bus=root_port13,memdev=cxl-mem1,lsa=cxl-lsa1,id=cxl-pmem0 \
> +  -device cxl-type3,bus=root_port13,persistent-memdev=cxl-mem1,lsa=cxl-lsa1,id=cxl-pmem0 \
>     -device cxl-rp,port=1,bus=cxl.1,id=root_port14,chassis=0,slot=3 \
> -  -device cxl-type3,bus=root_port14,memdev=cxl-mem2,lsa=cxl-lsa2,id=cxl-pmem1 \
> +  -device cxl-type3,bus=root_port14,persistent-memdev=cxl-mem2,lsa=cxl-lsa2,id=cxl-pmem1 \
>     -device cxl-rp,port=0,bus=cxl.2,id=root_port15,chassis=0,slot=5 \
> -  -device cxl-type3,bus=root_port15,memdev=cxl-mem3,lsa=cxl-lsa3,id=cxl-pmem2 \
> +  -device cxl-type3,bus=root_port15,persistent-memdev=cxl-mem3,lsa=cxl-lsa3,id=cxl-pmem2 \
>     -device cxl-rp,port=1,bus=cxl.2,id=root_port16,chassis=0,slot=6 \
> -  -device cxl-type3,bus=root_port16,memdev=cxl-mem4,lsa=cxl-lsa4,id=cxl-pmem3 \
> +  -device cxl-type3,bus=root_port16,persistent-memdev=cxl-mem4,lsa=cxl-lsa4,id=cxl-pmem3 \
>     -M cxl-fmw.0.targets.0=cxl.1,cxl-fmw.0.targets.1=cxl.2,cxl-fmw.0.size=4G,cxl-fmw.0.interleave-granularity=8k
>   
>   An example of 4 devices below a switch suitable for 1, 2 or 4 way interleave::
> @@ -354,15 +375,23 @@ An example of 4 devices below a switch suitable for 1, 2 or 4 way interleave::
>     -device cxl-rp,port=1,bus=cxl.1,id=root_port1,chassis=0,slot=1 \
>     -device cxl-upstream,bus=root_port0,id=us0 \
>     -device cxl-downstream,port=0,bus=us0,id=swport0,chassis=0,slot=4 \
> -  -device cxl-type3,bus=swport0,memdev=cxl-mem0,lsa=cxl-lsa0,id=cxl-pmem0,size=256M \
> +  -device cxl-type3,bus=swport0,persistent-memdev=cxl-mem0,lsa=cxl-lsa0,id=cxl-pmem0,size=256M \
>     -device cxl-downstream,port=1,bus=us0,id=swport1,chassis=0,slot=5 \
> -  -device cxl-type3,bus=swport1,memdev=cxl-mem1,lsa=cxl-lsa1,id=cxl-pmem1,size=256M \
> +  -device cxl-type3,bus=swport1,persistent-memdev=cxl-mem1,lsa=cxl-lsa1,id=cxl-pmem1,size=256M \
>     -device cxl-downstream,port=2,bus=us0,id=swport2,chassis=0,slot=6 \
> -  -device cxl-type3,bus=swport2,memdev=cxl-mem2,lsa=cxl-lsa2,id=cxl-pmem2,size=256M \
> +  -device cxl-type3,bus=swport2,persistent-memdev=cxl-mem2,lsa=cxl-lsa2,id=cxl-pmem2,size=256M \
>     -device cxl-downstream,port=3,bus=us0,id=swport3,chassis=0,slot=7 \
> -  -device cxl-type3,bus=swport3,memdev=cxl-mem3,lsa=cxl-lsa3,id=cxl-pmem3,size=256M \
> +  -device cxl-type3,bus=swport3,persistent-memdev=cxl-mem3,lsa=cxl-lsa3,id=cxl-pmem3,size=256M \
>     -M cxl-fmw.0.targets.0=cxl.1,cxl-fmw.0.size=4G,cxl-fmw.0.interleave-granularity=4k
>   
> +Deprecations
> +------------
> +
> +The Type 3 device [memdev] attribute has been deprecated in favor of the
> +[persistent-memdev] attributes. [memdev] will default to a persistent memory
> +device for backward compatibility and is incapable of being used in combination
> +with [persistent-memdev].
> +

Probably worth mentioning & referring this in docs/about/deprecated.rst.