Re: [RFC 3/7] hw/mem/cxl_type3: Add a parameter to pass number of DC regions the device supports in qemu command line

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

On Thu, 11 May 2023 17:56:40 +0000
Fan Ni <fan.ni@samsung.com> wrote:

> From: Fan Ni <nifan@outlook.com>
> 
> Add a property 'num-dc-regions' to ct3_props to allow users to create DC
> regions.
> With the change, users can control the number of DC regions the device
> supports.
> To make it easier, other parameters of the region like region base, length,
> and block size are hard coded. If desired, these parameters
> can be added easily.
> 
> Signed-off-by: Fan Ni <fan.ni@samsung.com>

Ok. This is fine for initial testing, but we need to figure out how to actually
handle DCD regions and how to back them with memory.
Probably a 3rd memory backend to cover all the DCD regions?
Default perhaps to an even spread of a few regions (no real point in doing
more than 2 for initial support, fall back to 1 region if size is too small).
We will want to be able to mess with regions from the FM-API but lots more to
do there before that matters and we can still have default config for any
regions we define now.

Jonathan

> ---
>  hw/mem/cxl_type3.c | 32 ++++++++++++++++++++++++++++++++
>  1 file changed, 32 insertions(+)
> 
> diff --git a/hw/mem/cxl_type3.c b/hw/mem/cxl_type3.c
> index 2b483d3d8e..b9c375d9b4 100644
> --- a/hw/mem/cxl_type3.c
> +++ b/hw/mem/cxl_type3.c
> @@ -684,6 +684,34 @@ static void ct3d_reg_write(void *opaque, hwaddr offset, uint64_t value,
>      }
>  }
>  
> +/*
> + * Create a dc region to test "Get Dynamic Capacity Configuration" command.
> + */
> +static int cxl_create_toy_regions(CXLType3Dev *ct3d)
> +{
> +	int i;
> +	uint64_t region_base = ct3d->hostvmem?ct3d->hostvmem->size
> +		+ ct3d->hostpmem->size:ct3d->hostpmem->size;
> +	uint64_t region_len = 1024*1024*1024;
> +	uint64_t decode_len = 4; /* 4*256MB */
> +	uint64_t blk_size = 2*1024*1024;
> +	struct CXLDCD_Region *region;
> +
> +	for (i = 0; i < ct3d->dc.num_regions; i++) {
> +		region = &ct3d->dc.regions[i];
> +		region->base = region_base;
> +		region->decode_len = decode_len;
> +		region->len = region_len;
> +		region->block_size = blk_size;
> +		/* dsmad_handle is set when creating cdat table entries */
> +		region->flags = 0;
> +
> +		region_base += region->len;
> +	}
> +
> +	return 0;
> +}
> +
>  static bool cxl_setup_memory(CXLType3Dev *ct3d, Error **errp)
>  {
>      DeviceState *ds = DEVICE(ct3d);
> @@ -752,6 +780,9 @@ static bool cxl_setup_memory(CXLType3Dev *ct3d, Error **errp)
>          g_free(p_name);
>      }
>  
> +	if (cxl_create_toy_regions(ct3d))
> +		return false;
> +
>      return true;
>  }
>  
> @@ -1036,6 +1067,7 @@ static Property ct3_props[] = {
>      DEFINE_PROP_UINT64("sn", CXLType3Dev, sn, UI64_NULL),
>      DEFINE_PROP_STRING("cdat", CXLType3Dev, cxl_cstate.cdat.filename),
>      DEFINE_PROP_UINT16("spdm", CXLType3Dev, spdm_port, 0),
> +	DEFINE_PROP_UINT8("num-dc-regions", CXLType3Dev, dc.num_regions, 0),
>      DEFINE_PROP_END_OF_LIST(),
>  };
>