diff mbox series

[RFC,net-next,v4,5/9] net/smc: Introduce an interface for getting DMB attribute

Message ID 1679887699-54797-6-git-send-email-guwen@linux.alibaba.com (mailing list archive)
State RFC
Delegated to: Netdev Maintainers
Headers show
Series net/smc: Introduce SMC-D-based OS internal communication acceleration | expand

Checks

Context Check Description
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for net-next
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 18 this patch: 18
netdev/cc_maintainers success CCed 9 of 9 maintainers
netdev/build_clang success Errors and warnings before: 18 this patch: 18
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 18 this patch: 18
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 38 lines checked
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

Wen Gu March 27, 2023, 3:28 a.m. UTC
On s390, since all OSs run on a kind of machine level hypervisor which
is a partitioning hypervisor without paging, the sndbufs and DMBs in
such case are unable to be mapped to the same physical memory.

However, in other scene, such as communication within the same OS instance
(loopback) or between guests of a paging hypervisor (see [1]), eg. KVM,
the sndbufs and DMBs can be mapped to the same physical memory to avoid
memory copy from sndbufs to DMBs.

So this patch introduces an interface to smcd_ops for users to judge
whether DMB-map is available. And for reuse, the interface is designed
to return DMB attribute, not only mappability.

[1] https://lists.oasis-open.org/archives/virtio-comment/202302/msg00148.html

Signed-off-by: Wen Gu <guwen@linux.alibaba.com>
---
 include/net/smc.h | 5 +++++
 net/smc/smc_ism.c | 8 ++++++++
 net/smc/smc_ism.h | 1 +
 3 files changed, 14 insertions(+)
diff mbox series

Patch

diff --git a/include/net/smc.h b/include/net/smc.h
index 021ca42..e39ac41 100644
--- a/include/net/smc.h
+++ b/include/net/smc.h
@@ -55,6 +55,10 @@  struct smcd_seid {
 
 #define ISM_ERROR	0xFFFF
 
+enum {
+	ISM_DMB_MAPPABLE = 0,
+};
+
 struct smcd_dev;
 
 struct smcd_ops {
@@ -77,6 +81,7 @@  struct smcd_ops {
 	u64 (*get_local_gid)(struct smcd_dev *dev);
 	u16 (*get_chid)(struct smcd_dev *dev);
 	struct device* (*get_dev)(struct smcd_dev *dev);
+	int (*get_dev_dmb_attr)(struct smcd_dev *dev);
 };
 
 struct smcd_dev {
diff --git a/net/smc/smc_ism.c b/net/smc/smc_ism.c
index f638999..a21c867 100644
--- a/net/smc/smc_ism.c
+++ b/net/smc/smc_ism.c
@@ -233,6 +233,14 @@  int smc_ism_unregister_dmb(struct smcd_dev *smcd, struct smc_buf_desc *dmb_desc)
 	return rc;
 }
 
+bool smc_ism_dmb_mappable(struct smcd_dev *smcd)
+{
+	if (smcd->ops->get_dev_dmb_attr &&
+	    (smcd->ops->get_dev_dmb_attr(smcd) & (1 << ISM_DMB_MAPPABLE)))
+		return true;
+	return false;
+}
+
 int smc_ism_register_dmb(struct smc_link_group *lgr, int dmb_len,
 			 struct smc_buf_desc *dmb_desc)
 {
diff --git a/net/smc/smc_ism.h b/net/smc/smc_ism.h
index 870ff7b..0ddaa45 100644
--- a/net/smc/smc_ism.h
+++ b/net/smc/smc_ism.h
@@ -39,6 +39,7 @@  struct smc_ism_vlanid {			/* VLAN id set on ISM device */
 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_dmb_mappable(struct smcd_dev *smcd);
 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);