Re: [PATCH 0/4 v3] Multi-Region and Volatile Memory support for CXL Type-3 Devices

["Michael S. Tsirkin" <mst@redhat.com>]

On Tue, Oct 25, 2022 at 08:47:33PM -0400, Gregory Price wrote:
> Submitted as an extention to the multi-feature branch maintained
> by Jonathan Cameron at:
> https://gitlab.com/jic23/qemu/-/tree/cxl-2022-10-24 

BTW pls set subject prefix for all patches, and put it before the patch #.
-v parameter to format-patch will do this for you.

> 
> Summary of Changes:
> 1) E820 CFMW Bug fix.  
> 2) Add CXL_CAPACITY_MULTIPLIER definition to replace magic numbers
> 3) Multi-Region and Volatile Memory support for CXL Type-3 Devices
> 4) CXL Type-3 SRAT Generation when NUMA node is attached to memdev
> 
> 
> Regarding the E820 fix
>   * This bugfix is required for memory regions to work on x86
>   * input from Dan Williams and others suggest that E820 entry for
>     the CFMW should not exist, as it is expected to be dynamically
>     assigned at runtime.  If this entry exists, it instead blocks
>     region creation by nature of the memory region being marked as
>     reserved.
> 
> Regarding Multi-Region and Volatile Memory
>   * Developed with input from Jonathan Cameron and Davidlohr Bueso.
> 
> Regarding SRAT Generation for Type-3 Devices
>   * Co-Developed by Davidlohr Bueso.  Built from his base patch and
>     extended to work with both volatile and persistent regions.
>   * This can be used to demonstrate static type-3 device mapping and
>     testing numa-access to type-3 device memory regions.
> 
> 
> This series brings 3 features to CXL Type-3 Devices:
>     1) Volatile Memory Region support
>     2) Multi-Region support (1 Volatile, 1 Persistent)
>     3) (optional) SRAT Entry generation for type-3 device regions
> 
> In this series we implement multi-region and volatile region support
> through 7 major changes to CXL devices
>     1) The HostMemoryBackend [hostmem] has been replaced by two
>        [hostvmem] and [hostpmem] to store volatile and persistent
>        memory respectively
>     2) The single AddressSpace has been replaced by two AddressSpaces
>        [hostvmem_as] and [hostpmem_as] to map respective memdevs.
>     3) Each memory region size and total region are stored separately
>     4) The CDAT and DVSEC memory map entries have been updated:
>        a) if vmem is present, vmem is mapped at DPA(0)
>        b) if pmem is present
>           i)  and vmem is present, pmem is mapped at DPA(vmem->size)
>           ii) else, pmem is mapped at DPA(0)
>        c) partitioning of pmem is not supported in this patch set but
>           has been discussed and this design should suffice.
>     5) Read/Write functions have been updated to access AddressSpaces
>        according to the mapping described in #4
>     6) cxl-mailbox has been updated to report the respective size of
>        volatile and persistent memory regions
>     7) SRAT entries may optionally be generated by manually assigning
>        memdevs to a cpuless numa node
> 
> To support the Device Physical Address (DPA) Mapping decisions, see
> CXL Spec (3.0) Section 8.2.9.8.2.0 - Get Partition Info:
>   Active Volatile Memory
>     The device shall provide this volatile capacity starting at DPA 0
>   Active Persistent Memory
>     The device shall provide this persistent capacity starting at the
>     DPA immediately following the volatile capacity
> 
> Partitioning of Persistent Memory regions may be supported on
> following patch sets.
> 
> 
> Gregory Price (4):
>   hw/i386/pc.c: CXL Fixed Memory Window should not reserve e820 in bios
>   hw/cxl: Add CXL_CAPACITY_MULTIPLIER definition
>   hw/cxl: Multi-Region CXL Type-3 Devices (Volatile and Persistent)
>   hw/acpi/cxl.c: Fill in SRAT for vmem/pmem if NUMA node is assigned
> 
>  docs/system/devices/cxl.rst |  74 ++++++++--
>  hw/acpi/cxl.c               |  67 +++++++++
>  hw/cxl/cxl-mailbox-utils.c  |  23 +--
>  hw/i386/acpi-build.c        |   4 +
>  hw/i386/pc.c                |   2 -
>  hw/mem/cxl_type3.c          | 274 +++++++++++++++++++++++++++---------
>  include/hw/acpi/cxl.h       |   1 +
>  include/hw/cxl/cxl_device.h |  11 +-
>  tests/qtest/cxl-test.c      | 111 +++++++++++----
>  9 files changed, 443 insertions(+), 124 deletions(-)
> 
> -- 
> 2.37.3