From: Logan Gunthorpe <logang@deltatee.com>
To: linux-kernel@vger.kernel.org, linux-ntb@googlegroups.com,
linux-pci@vger.kernel.org, iommu@lists.linux-foundation.org,
linux-kselftest@vger.kernel.org, Jon Mason <jdmason@kudzu.us>,
Bjorn Helgaas <bhelgaas@google.com>,
Joerg Roedel <joro@8bytes.org>
Cc: Allen Hubbe <allenbh@gmail.com>,
Dave Jiang <dave.jiang@intel.com>,
Serge Semin <fancer.lancer@gmail.com>,
Eric Pilmore <epilmore@gigaio.com>,
Logan Gunthorpe <logang@deltatee.com>
Subject: [PATCH 4/9] NTB: Introduce functions to calculate multi-port resource index
Date: Thu, 31 Jan 2019 11:56:51 -0700 [thread overview]
Message-ID: <20190131185656.17972-5-logang@deltatee.com> (raw)
In-Reply-To: <20190131185656.17972-1-logang@deltatee.com>
When using multi-ports each port uses resources (dbs, msgs, mws, etc)
on every other port. Creating a mapping for these resources such that
each port has a corresponding resource on every other port is a bit
tricky.
Introduce the ntb_peer_resource_idx() function for this purpose.
It returns the peer resource number that will correspond with the
local peer index on the remote peer.
Also, introduce ntb_peer_highest_mw_idx() which will use
ntb_peer_resource_idx() but return the MW index starting with the
highest index and working down.
Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Cc: Jon Mason <jdmason@kudzu.us>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: Allen Hubbe <allenbh@gmail.com>
---
include/linux/ntb.h | 70 +++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 70 insertions(+)
diff --git a/include/linux/ntb.h b/include/linux/ntb.h
index 181d16601dd9..f5c69d853489 100644
--- a/include/linux/ntb.h
+++ b/include/linux/ntb.h
@@ -1502,4 +1502,74 @@ static inline int ntb_peer_msg_write(struct ntb_dev *ntb, int pidx, int midx,
return ntb->ops->peer_msg_write(ntb, pidx, midx, msg);
}
+/**
+ * ntb_peer_resource_idx() - get a resource index for a given peer idx
+ * @ntb: NTB device context.
+ * @pidx: Peer port index.
+ *
+ * When constructing a graph of peers, each remote peer must use a different
+ * resource index (mw, doorbell, etc) to communicate with each other
+ * peer.
+ *
+ * In a two peer system, this function should always return 0 such that
+ * resource 0 points to the remote peer on both ports.
+ *
+ * In a 5 peer system, this function will return the following matrix
+ *
+ * pidx \ port 0 1 2 3 4
+ * 0 0 0 1 2 3
+ * 1 0 1 2 3 4
+ * 2 0 1 2 3 4
+ * 3 0 1 2 3 4
+ *
+ * For example, if this function is used to program peer's memory
+ * windows, port 0 will program MW 0 on all it's peers to point to itself.
+ * port 1 will program MW 0 in port 0 to point to itself and MW 1 on all
+ * other ports. etc.
+ *
+ * For the legacy two host case, ntb_port_number() and ntb_peer_port_number()
+ * both return zero and therefore this function will always return zero.
+ * So MW 0 on each host would be programmed to point to the other host.
+ *
+ * Return: the resource index to use for that peer.
+ */
+static inline int ntb_peer_resource_idx(struct ntb_dev *ntb, int pidx)
+{
+ int local_port, peer_port;
+
+ if (pidx >= ntb_peer_port_count(ntb))
+ return -EINVAL;
+
+ local_port = ntb_port_number(ntb);
+ peer_port = ntb_peer_port_number(ntb, pidx);
+
+ if (peer_port < local_port)
+ return local_port - 1;
+ else
+ return local_port;
+}
+
+/**
+ * ntb_peer_highest_mw_idx() - get a memory window index for a given peer idx
+ * using the highest index memory windows first
+ *
+ * @ntb: NTB device context.
+ * @pidx: Peer port index.
+ *
+ * Like ntb_peer_resource_idx(), except it returns indexes starting with
+ * last memory window index.
+ *
+ * Return: the resource index to use for that peer.
+ */
+static inline int ntb_peer_highest_mw_idx(struct ntb_dev *ntb, int pidx)
+{
+ int ret;
+
+ ret = ntb_peer_resource_idx(ntb, pidx);
+ if (ret < 0)
+ return ret;
+
+ return ntb_mw_count(ntb, pidx) - ret - 1;
+}
+
#endif
--
2.19.0
next prev parent reply other threads:[~2019-01-31 18:56 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-31 18:56 [PATCH 0/9] Support using MSI interrupts in ntb_transport Logan Gunthorpe
2019-01-31 18:56 ` [PATCH 1/9] iommu/vt-d: Allow interrupts from the entire bus for aliased devices Logan Gunthorpe
2019-02-01 16:44 ` Joerg Roedel
2019-02-01 17:27 ` Logan Gunthorpe
2019-02-05 19:19 ` Jacob Pan
2019-02-05 20:40 ` Logan Gunthorpe
2019-02-05 23:58 ` Jacob Pan
2019-01-31 18:56 ` [PATCH 2/9] PCI/MSI: Support allocating virtual MSI interrupts Logan Gunthorpe
2019-01-31 22:39 ` Bjorn Helgaas
2019-01-31 22:52 ` Logan Gunthorpe
2019-02-01 19:23 ` Bjorn Helgaas
2019-01-31 18:56 ` [PATCH 3/9] PCI/switchtec: Add module parameter to request more interrupts Logan Gunthorpe
2019-01-31 18:56 ` Logan Gunthorpe [this message]
2019-01-31 18:56 ` [PATCH 5/9] NTB: Rename ntb.c to support multiple source files in the module Logan Gunthorpe
2019-01-31 18:56 ` [PATCH 6/9] NTB: Introduce MSI library Logan Gunthorpe
2019-01-31 18:56 ` [PATCH 7/9] NTB: Introduce NTB MSI Test Client Logan Gunthorpe
2019-01-31 18:56 ` [PATCH 8/9] NTB: Add ntb_msi_test support to ntb_test Logan Gunthorpe
2019-01-31 18:56 ` [PATCH 9/9] NTB: Add MSI interrupt support to ntb_transport Logan Gunthorpe
2019-01-31 20:20 ` [PATCH 0/9] Support using MSI interrupts in ntb_transport Dave Jiang
2019-01-31 20:48 ` Logan Gunthorpe
[not found] ` <bafe9db4-6d5b-0453-d7e7-e49e9293dd01-OTvnGxWRz7hWk0Htik3J/w@public.gmane.org>
2019-01-31 20:58 ` Dave Jiang
[not found] ` <ea7b7c3c-8ed5-51ec-022a-7d28a5afce82-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
2019-01-31 22:39 ` Logan Gunthorpe
[not found] ` <29f7e3fe-5354-6156-1243-7248ffb2249f-OTvnGxWRz7hWk0Htik3J/w@public.gmane.org>
2019-01-31 22:46 ` Dave Jiang
2019-01-31 23:41 ` Logan Gunthorpe
2019-01-31 23:48 ` Dave Jiang
2019-01-31 23:52 ` Logan Gunthorpe
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