Re: [PATCH v8 08/14] hw/mem/cxl_type3: Add host backend and address space handling for DC regions

[Jonathan Cameron]

On Thu, 23 May 2024 10:44:48 -0700
nifan.cxl@gmail.com wrote:

> From: Fan Ni <fan.ni@samsung.com>
> 
> Add (file/memory backed) host backend for DCD. All the dynamic capacity
> regions will share a single, large enough host backend. Set up address
> space for DC regions to support read/write operations to dynamic capacity
> for DCD.
> 
> With the change, the following support is added:
> 1. Add a new property to type3 device "volatile-dc-memdev" to point to host
>    memory backend for dynamic capacity. Currently, all DC regions share one
>    host backend;
> 2. Add namespace for dynamic capacity for read/write support;
> 3. Create cdat entries for each dynamic capacity region.
> 
> Reviewed-by: Gregory Price <gregory.price@memverge.com>
> Signed-off-by: Fan Ni <fan.ni@samsung.com>

>      dvsec = (uint8_t *)&(CXLDVSECDevice){
> @@ -579,11 +622,28 @@ static bool cxl_create_dc_regions(CXLType3Dev *ct3d, 
> Error **errp)
>  {
>      int i;
>      uint64_t region_base = 0;
> -    uint64_t region_len =  2 * GiB;
> -    uint64_t decode_len = 2 * GiB;
> +    uint64_t region_len;
> +    uint64_t decode_len;
>      uint64_t blk_size = 2 * MiB;
>      CXLDCRegion *region;
>      MemoryRegion *mr;
> +    uint64_t dc_size;
> +
> +    mr = host_memory_backend_get_memory(ct3d->dc.host_dc);
> +    dc_size = memory_region_size(mr);
> +    region_len = DIV_ROUND_UP(dc_size, ct3d->dc.num_regions);
> +
> +    if (dc_size % (ct3d->dc.num_regions * CXL_CAPACITY_MULTIPLIER) != 0) {
> +        error_setg(errp, "backend size is not multiple of region len: 0x%lx",

Just seen a build error for this in mst's gitlab.
Needs to be the messy PRIx64(not tested) e.g.

    error_setg(errp, "backend size is not multiple of region len: " PRIx64,
               region_len);

Michael, do you want a new version, or are you happy to fix this up?

Thanks,

Jonathan

> +                   region_len);
> +        return false;
> +    }
> +    if (region_len % CXL_CAPACITY_MULTIPLIER != 0) {
> +        error_setg(errp, "DC region size is unaligned to 0x%lx",
> +                   CXL_CAPACITY_MULTIPLIER);
> +        return false;
> +    }
> +    decode_len = region_len;
>  
>      if (ct3d->hostvmem) {
>          mr = host_memory_backend_get_memory(ct3d->hostvmem);
> @@ -610,6 +670,7 @@ static bool cxl_create_dc_regions(CXLType3Dev *ct3d, 
> Error **errp)
>              /* dsmad_handle set when creating CDAT table entries */
>              .flags = 0,
>          };
> +        ct3d->dc.total_capacity += region->len;
>      }
>  
>      return true;
> @@ -619,7 +680,8 @@ static bool cxl_setup_memory(CXLType3Dev *ct3d, Error 
> **errp)
>  {
>      DeviceState *ds = DEVICE(ct3d);
>  
> -    if (!ct3d->hostmem && !ct3d->hostvmem && !ct3d->hostpmem) {
> +    if (!ct3d->hostmem && !ct3d->hostvmem && !ct3d->hostpmem
> +        && !ct3d->dc.num_regions) {
>          error_setg(errp, "at least one memdev property must be set");
>          return false;
>      } else if (ct3d->hostmem && ct3d->hostpmem) {
> @@ -683,7 +745,37 @@ static bool cxl_setup_memory(CXLType3Dev *ct3d, Error 
> **errp)
>          g_free(p_name);
>      }
>  
> +    ct3d->dc.total_capacity = 0;
>      if (ct3d->dc.num_regions > 0) {
> +        MemoryRegion *dc_mr;
> +        char *dc_name;
> +
> +        if (!ct3d->dc.host_dc) {
> +            error_setg(errp, "dynamic capacity must have a backing device");
> +            return false;
> +        }
> +
> +        dc_mr = host_memory_backend_get_memory(ct3d->dc.host_dc);
> +        if (!dc_mr) {
> +            error_setg(errp, "dynamic capacity must have a backing device");
> +            return false;
> +        }
> +
> +        /*
> +         * Set DC regions as volatile for now, non-volatile support can
> +         * be added in the future if needed.
> +         */
> +        memory_region_set_nonvolatile(dc_mr, false);
> +        memory_region_set_enabled(dc_mr, true);
> +        host_memory_backend_set_mapped(ct3d->dc.host_dc, true);
> +        if (ds->id) {
> +            dc_name = g_strdup_printf("cxl-dcd-dpa-dc-space:%s", ds->id);
> +        } else {
> +            dc_name = g_strdup("cxl-dcd-dpa-dc-space");
> +        }
> +        address_space_init(&ct3d->dc.host_dc_as, dc_mr, dc_name);
> +        g_free(dc_name);
> +
>          if (!cxl_create_dc_regions(ct3d, errp)) {
>              error_append_hint(errp, "setup DC regions failed");
>              return false;
> @@ -779,6 +871,9 @@ err_release_cdat:
>  err_free_special_ops:
>      g_free(regs->special_ops);
>  err_address_space_free:
> +    if (ct3d->dc.host_dc) {
> +        address_space_destroy(&ct3d->dc.host_dc_as);
> +    }
>      if (ct3d->hostpmem) {
>          address_space_destroy(&ct3d->hostpmem_as);
>      }
> @@ -797,6 +892,9 @@ static void ct3_exit(PCIDevice *pci_dev)
>      pcie_aer_exit(pci_dev);
>      cxl_doe_cdat_release(cxl_cstate);
>      g_free(regs->special_ops);
> +    if (ct3d->dc.host_dc) {
> +        address_space_destroy(&ct3d->dc.host_dc_as);
> +    }
>      if (ct3d->hostpmem) {
>          address_space_destroy(&ct3d->hostpmem_as);
>      }
> @@ -875,16 +973,23 @@ static int cxl_type3_hpa_to_as_and_dpa(CXLType3Dev 
> *ct3d,
>                                         AddressSpace **as,
>                                         uint64_t *dpa_offset)
>  {
> -    MemoryRegion *vmr = NULL, *pmr = NULL;
> +    MemoryRegion *vmr = NULL, *pmr = NULL, *dc_mr = NULL;
> +    uint64_t vmr_size = 0, pmr_size = 0, dc_size = 0;
>  
>      if (ct3d->hostvmem) {
>          vmr = host_memory_backend_get_memory(ct3d->hostvmem);
> +        vmr_size = memory_region_size(vmr);
>      }
>      if (ct3d->hostpmem) {
>          pmr = host_memory_backend_get_memory(ct3d->hostpmem);
> +        pmr_size = memory_region_size(pmr);
> +    }
> +    if (ct3d->dc.host_dc) {
> +        dc_mr = host_memory_backend_get_memory(ct3d->dc.host_dc);
> +        dc_size = memory_region_size(dc_mr);
>      }
>  
> -    if (!vmr && !pmr) {
> +    if (!vmr && !pmr && !dc_mr) {
>          return -ENODEV;
>      }
>  
> @@ -892,19 +997,18 @@ static int cxl_type3_hpa_to_as_and_dpa(CXLType3Dev 
> *ct3d,
>          return -EINVAL;
>      }
>  
> -    if (*dpa_offset > ct3d->cxl_dstate.static_mem_size) {
> +    if (*dpa_offset >= vmr_size + pmr_size + dc_size) {
>          return -EINVAL;
>      }
>  
> -    if (vmr) {
> -        if (*dpa_offset < memory_region_size(vmr)) {
> -            *as = &ct3d->hostvmem_as;
> -        } else {
> -            *as = &ct3d->hostpmem_as;
> -            *dpa_offset -= memory_region_size(vmr);
> -        }
> -    } else {
> +    if (*dpa_offset < vmr_size) {
> +        *as = &ct3d->hostvmem_as;
> +    } else if (*dpa_offset < vmr_size + pmr_size) {
>          *as = &ct3d->hostpmem_as;
> +        *dpa_offset -= vmr_size;
> +    } else {
> +        *as = &ct3d->dc.host_dc_as;
> +        *dpa_offset -= (vmr_size + pmr_size);
>      }
>  
>      return 0;
> @@ -986,6 +1090,8 @@ static Property ct3_props[] = {
>      DEFINE_PROP_UINT64("sn", CXLType3Dev, sn, UI64_NULL),
>      DEFINE_PROP_STRING("cdat", CXLType3Dev, cxl_cstate.cdat.filename),
>      DEFINE_PROP_UINT8("num-dc-regions", CXLType3Dev, dc.num_regions, 0),
> +    DEFINE_PROP_LINK("volatile-dc-memdev", CXLType3Dev, dc.host_dc,
> +                     TYPE_MEMORY_BACKEND, HostMemoryBackend *),
>      DEFINE_PROP_END_OF_LIST(),
>  };
>  
> @@ -1052,33 +1158,39 @@ static void set_lsa(CXLType3Dev *ct3d, const void 
> *buf, uint64_t size,
>  
>  static bool set_cacheline(CXLType3Dev *ct3d, uint64_t dpa_offset, uint8_t 
> *data)
>  {
> -    MemoryRegion *vmr = NULL, *pmr = NULL;
> +    MemoryRegion *vmr = NULL, *pmr = NULL, *dc_mr = NULL;
>      AddressSpace *as;
> +    uint64_t vmr_size = 0, pmr_size = 0, dc_size = 0;
>  
>      if (ct3d->hostvmem) {
>          vmr = host_memory_backend_get_memory(ct3d->hostvmem);
> +        vmr_size = memory_region_size(vmr);
>      }
>      if (ct3d->hostpmem) {
>          pmr = host_memory_backend_get_memory(ct3d->hostpmem);
> +        pmr_size = memory_region_size(pmr);
>      }
> +    if (ct3d->dc.host_dc) {
> +        dc_mr = host_memory_backend_get_memory(ct3d->dc.host_dc);
> +        dc_size = memory_region_size(dc_mr);
> +     }
>  
> -    if (!vmr && !pmr) {
> +    if (!vmr && !pmr && !dc_mr) {
>          return false;
>      }
>  
> -    if (dpa_offset + CXL_CACHE_LINE_SIZE > ct3d->cxl_dstate.static_mem_size) 
> {
> +    if (dpa_offset + CXL_CACHE_LINE_SIZE > vmr_size + pmr_size + dc_size) {
>          return false;
>      }
>  
> -    if (vmr) {
> -        if (dpa_offset < memory_region_size(vmr)) {
> -            as = &ct3d->hostvmem_as;
> -        } else {
> -            as = &ct3d->hostpmem_as;
> -            dpa_offset -= memory_region_size(vmr);
> -        }
> -    } else {
> +    if (dpa_offset < vmr_size) {
> +        as = &ct3d->hostvmem_as;
> +    } else if (dpa_offset < vmr_size + pmr_size) {
>          as = &ct3d->hostpmem_as;
> +        dpa_offset -= vmr_size;
> +    } else {
> +        as = &ct3d->dc.host_dc_as;
> +        dpa_offset -= (vmr_size + pmr_size);
>      }
>  
>      address_space_write(as, dpa_offset, MEMTXATTRS_UNSPECIFIED, &data,
> diff --git a/include/hw/cxl/cxl_device.h b/include/hw/cxl/cxl_device.h
> index f7f56b44e3..c2c3df0d2a 100644
> --- a/include/hw/cxl/cxl_device.h
> +++ b/include/hw/cxl/cxl_device.h
> @@ -467,6 +467,14 @@ struct CXLType3Dev {
>      uint64_t poison_list_overflow_ts;
>  
>      struct dynamic_capacity {
> +        HostMemoryBackend *host_dc;
> +        AddressSpace host_dc_as;
> +        /*
> +         * total_capacity is equivalent to the dynamic capability
> +         * memory region size.
> +         */
> +        uint64_t total_capacity; /* 256M aligned */
> +
>          uint8_t num_regions; /* 0-8 regions */
>          CXLDCRegion regions[DCD_MAX_NUM_REGION];
>      } dc;