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net/smc: add operations to merge sndbuf with peer DMB

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In some scenarios using Emulated-ISM device, sndbuf can share the same
physical memory region with peer DMB to avoid data copy from one side
to the other. In such case the sndbuf is only a descriptor that
describes the shared memory and does not actually occupy memory, it's
more like a ghost buffer.

      +----------+                     +----------+
      | socket A |                     | socket B |
      +----------+                     +----------+
            |                               |
       +--------+                       +--------+
       | sndbuf |                       |  DMB   |
       |  desc  |                       |  desc  |
       +--------+                       +--------+
            |                               |
            |                          +----v-----+
            +-------------------------->  memory  |
                                       +----------+

So here introduces three new SMC-D device operations to check if this
feature is supported by device, and to {attach|detach} ghost sndbuf to
peer DMB. For now only loopback-ism supports this.

Signed-off-by: Wen Gu <guwen@linux.alibaba.com>
Reviewed-by: Wenjia Zhang <wenjia@linux.ibm.com>
Reviewed-and-tested-by: Jan Karcher <jaka@linux.ibm.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
This commit is contained in:
Wen Gu 2024-04-28 14:07:35 +08:00 committed by Paolo Abeni
parent 04791343d8
commit 4398888268
3 changed files with 47 additions and 0 deletions
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3
include/net/smc.h
View File

@ -74,6 +74,9 @@ struct smcd_ops {
int (*reset_vlan_required)(struct smcd_dev *dev);
int (*signal_event)(struct smcd_dev *dev, struct smcd_gid *rgid,
u32 trigger_irq, u32 event_code, u64 info);
int (*support_dmb_nocopy)(struct smcd_dev *dev);
int (*attach_dmb)(struct smcd_dev *dev, struct smcd_dmb *dmb);
int (*detach_dmb)(struct smcd_dev *dev, u64 token);
};
struct smcd_dev {

40
net/smc/smc_ism.c
View File

@ -250,6 +250,46 @@ int smc_ism_register_dmb(struct smc_link_group *lgr, int dmb_len,
return rc;
}
bool smc_ism_support_dmb_nocopy(struct smcd_dev *smcd)
{
/* for now only loopback-ism supports
* merging sndbuf with peer DMB to avoid
* data copies between them.
*/
return (smcd->ops->support_dmb_nocopy &&
smcd->ops->support_dmb_nocopy(smcd));
}
int smc_ism_attach_dmb(struct smcd_dev *dev, u64 token,
struct smc_buf_desc *dmb_desc)
{
struct smcd_dmb dmb;
int rc = 0;
if (!dev->ops->attach_dmb)
return -EINVAL;
memset(&dmb, 0, sizeof(dmb));
dmb.dmb_tok = token;
rc = dev->ops->attach_dmb(dev, &dmb);
if (!rc) {
dmb_desc->sba_idx = dmb.sba_idx;
dmb_desc->token = dmb.dmb_tok;
dmb_desc->cpu_addr = dmb.cpu_addr;
dmb_desc->dma_addr = dmb.dma_addr;
dmb_desc->len = dmb.dmb_len;
}
return rc;
}
int smc_ism_detach_dmb(struct smcd_dev *dev, u64 token)
{
if (!dev->ops->detach_dmb)
return -EINVAL;
return dev->ops->detach_dmb(dev, token);
}
static int smc_nl_handle_smcd_dev(struct smcd_dev *smcd,
struct sk_buff *skb,
struct netlink_callback *cb)

4
net/smc/smc_ism.h
View File

@ -48,6 +48,10 @@ int smc_ism_put_vlan(struct smcd_dev *dev, unsigned short vlan_id);
int smc_ism_register_dmb(struct smc_link_group *lgr, int buf_size,
struct smc_buf_desc *dmb_desc);
int smc_ism_unregister_dmb(struct smcd_dev *dev, struct smc_buf_desc *dmb_desc);
bool smc_ism_support_dmb_nocopy(struct smcd_dev *smcd);
int smc_ism_attach_dmb(struct smcd_dev *dev, u64 token,
struct smc_buf_desc *dmb_desc);
int smc_ism_detach_dmb(struct smcd_dev *dev, u64 token);
int smc_ism_signal_shutdown(struct smc_link_group *lgr);
void smc_ism_get_system_eid(u8 **eid);
u16 smc_ism_get_chid(struct smcd_dev *dev);