Re: [RFC 5/7] hw/cxl/cxl-mailbox-utils: Add mailbox commands to support add/release dynamic capacity response

[address@hidden]

The 05/15/2023 15:37, Jonathan Cameron wrote:
> On Thu, 11 May 2023 17:56:40 +0000
> Fan Ni <fan.ni@samsung.com> wrote:
> 
> > From: Fan Ni <nifan@outlook.com>
> > 
> > Per CXL spec 3.0, we implemented the two mailbox commands:
> > Add Dynamic Capacity Response (Opcode 4802h) 8.2.9.8.9.3, and
> > Release Dynamic Capacity Response (Opcode 4803h) 8.2.9.8.9.4.
> > 
> > Signed-off-by: Fan Ni <fan.ni@samsung.com>
> > ---
> >  hw/cxl/cxl-mailbox-utils.c  | 223 ++++++++++++++++++++++++++++++++++++
> >  include/hw/cxl/cxl_device.h |   3 +-
> >  2 files changed, 225 insertions(+), 1 deletion(-)
> > 
> > diff --git a/hw/cxl/cxl-mailbox-utils.c b/hw/cxl/cxl-mailbox-utils.c
> > index ed2ac154cb..7212934627 100644
> > --- a/hw/cxl/cxl-mailbox-utils.c
> > +++ b/hw/cxl/cxl-mailbox-utils.c
> > @@ -84,6 +84,8 @@ enum {
> >     DCD_CONFIG = 0x48, /*8.2.9.8.9*/
> >             #define GET_DC_REGION_CONFIG   0x0
> >             #define GET_DYN_CAP_EXT_LIST   0x1
> > +           #define ADD_DYN_CAP_RSP        0x2
> > +           #define RELEASE_DYN_CAP        0x3
> >      PHYSICAL_SWITCH = 0x51
> >          #define IDENTIFY_SWITCH_DEVICE      0x0
> >  };
> > @@ -1069,6 +1071,221 @@ static CXLRetCode 
> > cmd_dcd_get_dyn_cap_ext_list(struct cxl_cmd *cmd,
> >     return CXL_MBOX_SUCCESS;
> >  }
> >  
> > +static inline int test_bits(const unsigned long *addr, int nr, int size)
> 
> Not obvious what this does from the name.  Please add some docs.
> 
> > +{
> > +   unsigned long res = find_next_zero_bit(addr, size + nr, nr);
> > +
> > +   if (res >= nr + size)
> > +           return 1;
> > +   else
> > +           return 0;
> > +}
> > +
> > +static uint8_t find_region_id(struct CXLType3Dev *dev, uint64_t dpa
> 
> Operates only on things in dev->dc, so perhaps pass that instead.
dc is a struct defined inside CXLType3Dev struct, so will leave it as it
is for now.

Fan
> 
> > +           , uint64_t len)
> 
> comma on previous line.
> 
> > +{
> > +   int8_t i = dev->dc.num_regions-1;
> > +
> > +   while (i > 0 && dpa < dev->dc.regions[i].base)
> > +           i--;
> > +
> > +   if (dpa < dev->dc.regions[i].base
> > +                   || dpa + len > dev->dc.regions[i].base + 
> > dev->dc.regions[i].len)
> > +           return dev->dc.num_regions;
> > +
> > +   return i;
> > +}
> > +
> > +static CXLRetCode detect_malformed_extent_list(CXLType3Dev *dev, void 
> > *data)
> > +{
> > +   struct updated_dc_extent_list_in_pl {
> This is same as used in next function.  Pull it out of the functions and
> use that type rather than mapping via a void *data pointer.  
> 
> > +           uint32_t num_entries_updated;
> > +           uint8_t rsvd[4];
> > +           struct {
> > +                   uint64_t start_dpa;
> > +                   uint64_t len;
> > +                   uint8_t rsvd[8];
> > +           } QEMU_PACKED updated_entries[];
> > +   } QEMU_PACKED;
> > +
> > +   struct updated_dc_extent_list_in_pl *in = data;
> > +   unsigned long *blk_bitmap;
> > +   uint64_t min_block_size = dev->dc.regions[0].block_size;
> > +   struct CXLDCD_Region *region = &dev->dc.regions[0];
> > +   uint32_t i;
> > +   uint64_t dpa, len;
> > +   uint8_t rid;
> > +
> > +   for (i = 1; i < dev->dc.num_regions; i++) {
> > +           region = &dev->dc.regions[i];
> > +           if (min_block_size > region->block_size)
> > +                   min_block_size = region->block_size;
> > +   }
> > +   blk_bitmap = bitmap_new((region->len + region->base
> > +                           - dev->dc.regions[0].base) / min_block_size);
> > +   g_assert(blk_bitmap);
> 
> Abort in bitmap_new() anyway so no need for this.  Most qemu allocations
> don't need to be checked as they fail hard anyway so we never get to the 
> checks.
> 
> > +   bitmap_zero(blk_bitmap, (region->len + region->base
> > +                           - dev->dc.regions[0].base) / min_block_size);
> 
> bitmap_new() seems to use a g_malloc0 internally so no need to zero again here
> I think.
> 
> > +
> > +   for (i = 0; i < in->num_entries_updated; i++) {
> > +           dpa = in->updated_entries[i].start_dpa;
> > +           len = in->updated_entries[i].len;
> > +
> > +           rid = find_region_id(dev, dpa, len);
> > +           if (rid == dev->dc.num_regions) {
> 
> Use a goto and single cleanup path having set ret or similar to
> the particular issue.
> 
> > +                   g_free(blk_bitmap);
> > +                   return CXL_MBOX_INVALID_PA;
> > +           }
> > +           region = &dev->dc.regions[rid];
> > +           if (dpa % region->block_size || len % region->block_size) {
> > +                   g_free(blk_bitmap);
> > +                   return CXL_MBOX_INVALID_EXTENT_LIST;
> goto from here as well.. etc.
> 
> > +           }
> > +           /* the dpa range already covered by some other extents in the 
> > list */
> > +           if (test_bits(blk_bitmap, dpa/min_block_size, 
> > len/min_block_size)) {
> > +                   g_free(blk_bitmap);
> > +                   return CXL_MBOX_INVALID_EXTENT_LIST;
> > +           }
> > +           bitmap_set(blk_bitmap, dpa/min_block_size, len/min_block_size);
> > +   }
> > +
> > +   g_free(blk_bitmap);
> > +   return CXL_MBOX_SUCCESS;
> > +}
> > +
> > +/*
> > + * cxl spec 3.0: 8.2.9.8.9.3
> > + * Add Dynamic Capacity Response (opcode 4802h)
> > + * Assuming extent list is updated when a extent is added, when receiving
> > + * the response, verify and ensure the extent is utilized by the host, and
> > + * update extent list  as needed.
> 
> Double space in middle of sentence
> 
> > + **/
> > +static CXLRetCode cmd_dcd_add_dyn_cap_rsp(struct cxl_cmd *cmd,
> > +           CXLDeviceState *cxl_dstate,
> > +           uint16_t *len_unused)
> > +{
> > +   struct add_dyn_cap_ext_list_in_pl {
> > +           uint32_t num_entries_updated;
> > +           uint8_t rsvd[4];
> > +           struct {
> > +                   uint64_t start_dpa;
> > +                   uint64_t len;
> > +                   uint8_t rsvd[8];
> > +           } QEMU_PACKED updated_entries[];
> 
> These extent list entries keep turning up in the code. Pull that out of here
> to be a general 'Extent list element' or similar.
> 
> > +   } QEMU_PACKED;
> > +
> > +   struct add_dyn_cap_ext_list_in_pl *in = (void *)cmd->payload;
> > +   struct CXLType3Dev *ct3d = container_of(cxl_dstate, CXLType3Dev, 
> > cxl_dstate);
> > +   CXLDCDExtentList *extent_list = &ct3d->dc.extents;
> > +   CXLDCD_Extent *ent;
> > +   uint32_t i;
> > +   uint64_t dpa, len;
> > +   CXLRetCode rs;
> > +
> > +   if (in->num_entries_updated == 0)
> > +           return CXL_MBOX_SUCCESS;
> > +
> > +   rs = detect_malformed_extent_list(ct3d, in);
> > +   if (rs != CXL_MBOX_SUCCESS)
> > +           return rs;
> > +
> > +   for (i = 0; i < in->num_entries_updated; i++) {
> > +           dpa = in->updated_entries[i].start_dpa;
> > +           len = in->updated_entries[i].len;
> > +
> > +           /* Todo: check following
> > +            * One or more of the updated extent lists contain Starting DPA
> > +            * or Lengths that are out of range of a current extent list
> > +            * maintained by the device.
> > +            **/
> > +
> > +           QTAILQ_FOREACH(ent, extent_list, node) {
> 
> Add some comments here.  Is this a repeated entry test?
> 
> > +                   if (ent->start_dpa == dpa && ent->len == len)
> > +                           return CXL_MBOX_INVALID_PA;
> > +                   if (ent->start_dpa <= dpa
> > +                           && dpa + len <= ent->start_dpa + ent->len) {
> 
> Comment needed on this one. Why is it shrinking an existing entry?
> 
> > +                           ent->start_dpa = dpa;
> > +                           ent->len = len;
> > +                           break;
> 
> If you break here I think it will only result in return CXL_MBOX_SUCCESS so
> might as well do that here.
> 
> > +                   } else if ((dpa < ent->start_dpa + ent->len
> > +                           && dpa + len > ent->start_dpa + ent->len)
> 
> Above is new entry would contain existing one.
> 
> > +                           || (dpa < ent->start_dpa && dpa + len > 
> > ent->start_dpa))
> > +                           return CXL_MBOX_INVALID_EXTENT_LIST;
> > +           }
> > +           // a new extent added
> 
> Why?  This function generally need more documentation.
> 
> > +           if (!ent) {
> > +                   ent = g_new0(CXLDCD_Extent, 1);
> > +                   assert(ent);
> 
> No need.  g_new0 will already have blown up before you get here.
> 
> > +                   ent->start_dpa = dpa;
> > +                   ent->len = len;
> > +                   memset(ent->tag, 0, 0x10);
> Allocated empty just above, still empty so no need to set it again.
> > +                   ent->shared_seq = 0;
> > +                   QTAILQ_INSERT_TAIL(extent_list, ent, node);
> > +           }
> > +   }
> > +
> > +   return CXL_MBOX_SUCCESS;
> > +}
> > +
> > +/*
> > + * Spec 3.0: 8.2.9.8.9.4
> > + * Release Dynamic Capacity (opcode 4803h)
> > + **/
> > +static CXLRetCode cmd_dcd_release_dcd_capacity(struct cxl_cmd *cmd,
> > +           CXLDeviceState *cxl_dstate,
> > +           uint16_t *len_unused)
> > +{
> > +   struct release_dcd_cap_in_pl {
> > +           uint32_t num_entries_updated;
> > +           uint8_t rsvd[4];
> > +           struct {
> > +                   uint64_t start_dpa;
> > +                   uint64_t len;
> > +                   uint8_t rsvd[8];
> > +           } QEMU_PACKED updated_entries[];
> > +   } QEMU_PACKED;
> > +
> > +   struct release_dcd_cap_in_pl *in = (void *)cmd->payload;
> > +   struct CXLType3Dev *ct3d = container_of(cxl_dstate, CXLType3Dev, 
> > cxl_dstate);
> > +   CXLDCDExtentList *extent_list = &ct3d->dc.extents;
> > +   CXLDCD_Extent *ent;
> > +   uint32_t i;
> > +   uint64_t dpa, len;
> > +   CXLRetCode rs;
> > +
> > +   if (in->num_entries_updated == 0)
> > +           return CXL_MBOX_INVALID_INPUT;
> > +
> > +   rs = detect_malformed_extent_list(ct3d, in);
> > +   if (rs != CXL_MBOX_SUCCESS)
> > +           return rs;
> > +
> > +           /* Todo: check following
> > +            * One or more of the updated extent lists contain Starting DPA
> > +            * or Lengths that are out of range of a current extent list
> > +            * maintained by the device.
> > +            **/
> > +
> > +   for (i = 0; i < in->num_entries_updated; i++) {
> > +           dpa = in->updated_entries[i].start_dpa;
> > +           len = in->updated_entries[i].len;
> > +
> > +           QTAILQ_FOREACH(ent, extent_list, node) {
> > +                   if (ent->start_dpa == dpa && ent->len == len)
> 
> Do the remove here and comment on 'found entry' not needed.
> Note I think you can release partial extents so that will need handling at 
> some point.
> 
> > +                           break;
> > +                   else if ((dpa < ent->start_dpa + ent->len
> > +                           && dpa + len > ent->start_dpa + ent->len)
> > +                           || (dpa < ent->start_dpa && dpa + len > 
> > ent->start_dpa))
> Comment on this condition and why it's a problem.
> 
> > +                           return CXL_MBOX_INVALID_EXTENT_LIST;
> > +           }
> > +           /* found the entry, release it */
> > +           if (ent)
> > +                   QTAILQ_REMOVE(extent_list, ent, node);
> > +   }
> > +
> > +   return CXL_MBOX_SUCCESS;
> > +}
> > +
> >  #define IMMEDIATE_CONFIG_CHANGE (1 << 1)
> >  #define IMMEDIATE_DATA_CHANGE (1 << 2)
> >  #define IMMEDIATE_POLICY_CHANGE (1 << 3)
> > @@ -1112,6 +1329,12 @@ static struct cxl_cmd cxl_cmd_set[256][256] = {
> >     [DCD_CONFIG][GET_DYN_CAP_EXT_LIST] = {
> >             "DCD_GET_DYNAMIC_CAPACITY_EXTENT_LIST", 
> > cmd_dcd_get_dyn_cap_ext_list,
> >             8, 0 },
> > +   [DCD_CONFIG][ADD_DYN_CAP_RSP] = {
> > +           "ADD_DCD_DYNAMIC_CAPACITY_RESPONSE", cmd_dcd_add_dyn_cap_rsp,
> > +           ~0, IMMEDIATE_DATA_CHANGE },
> > +   [DCD_CONFIG][RELEASE_DYN_CAP] = {
> > +           "RELEASE_DCD_DYNAMIC_CAPACITY", cmd_dcd_release_dcd_capacity,
> > +           ~0, IMMEDIATE_DATA_CHANGE },
> >  };
> >  
> >  static struct cxl_cmd cxl_cmd_set_sw[256][256] = {
> > diff --git a/include/hw/cxl/cxl_device.h b/include/hw/cxl/cxl_device.h
> > index 20ad5e7411..c0c8fcc24b 100644
> > --- a/include/hw/cxl/cxl_device.h
> > +++ b/include/hw/cxl/cxl_device.h
> > @@ -131,7 +131,8 @@ typedef enum {
> >      CXL_MBOX_INCORRECT_PASSPHRASE = 0x14,
> >      CXL_MBOX_UNSUPPORTED_MAILBOX = 0x15,
> >      CXL_MBOX_INVALID_PAYLOAD_LENGTH = 0x16,
> > -    CXL_MBOX_MAX = 0x17
> > +   CXL_MBOX_INVALID_EXTENT_LIST = 0x17,
> 
> 0x1e in the spec.
> 
> > +   CXL_MBOX_MAX = 0x18
> >  } CXLRetCode;
> >  
> >  struct cxl_cmd;
> 

-- 
Fan Ni <nifan@outlook.com>