[PATCH v2 07/10] PCI/DOE: Create mailboxes on device enumeration

From: Lukas Wunner <lukas@wunner.de>
To: Bjorn Helgaas <helgaas@kernel.org>, linux-pci@vger.kernel.org
Cc: Gregory Price <gregory.price@memverge.com>,
	Ira Weiny <ira.weiny@intel.com>,
	Jonathan Cameron <Jonathan.Cameron@huawei.com>,
	Dan Williams <dan.j.williams@intel.com>,
	Alison Schofield <alison.schofield@intel.com>,
	Vishal Verma <vishal.l.verma@intel.com>,
	Dave Jiang <dave.jiang@intel.com>,
	"Li, Ming" <ming4.li@intel.com>, Hillf Danton <hdanton@sina.com>,
	Ben Widawsky <bwidawsk@kernel.org>,
	linuxarm@huawei.com, linux-cxl@vger.kernel.org
Subject: [PATCH v2 07/10] PCI/DOE: Create mailboxes on device enumeration
Date: Mon, 23 Jan 2023 11:17:00 +0100	[thread overview]
Message-ID: <5b03b8f4d2d04cf7e4997c71daee667c73eb427b.1674468099.git.lukas@wunner.de> (raw)
In-Reply-To: <cover.1674468099.git.lukas@wunner.de>

Currently a DOE instance cannot be shared by multiple drivers because
each driver creates its own pci_doe_mb struct for a given DOE instance.
For the same reason a DOE instance cannot be shared between the PCI core
and a driver.

Overcome this limitation by creating mailboxes in the PCI core on device
enumeration.  Provide a pci_find_doe_mailbox() API call to allow drivers
to get a pci_doe_mb for a given (pci_dev, vendor, protocol) triple.

On device removal, tear down mailboxes in two steps:

In pci_stop_dev(), before the driver is unbound, stop ongoing DOE
exchanges and prevent new ones from being scheduled.  This ensures that
a hot-removed device doesn't needlessly wait for a running exchange to
time out.

In pci_destroy_dev(), after the driver is unbound, free the mailboxes
and their internal data structures.

Tested-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
---
 drivers/pci/doe.c       | 71 +++++++++++++++++++++++++++++++++++++++++
 drivers/pci/pci.h       | 10 ++++++
 drivers/pci/probe.c     |  1 +
 drivers/pci/remove.c    |  2 ++
 include/linux/pci-doe.h |  2 ++
 include/linux/pci.h     |  3 ++
 6 files changed, 89 insertions(+)

diff --git a/drivers/pci/doe.c b/drivers/pci/doe.c
index cc1fdd75ad2a..06c57af05570 100644
--- a/drivers/pci/doe.c
+++ b/drivers/pci/doe.c
@@ -20,6 +20,8 @@
 #include <linux/pci-doe.h>
 #include <linux/workqueue.h>
 
+#include "pci.h"
+
 #define PCI_DOE_PROTOCOL_DISCOVERY 0
 
 /* Timeout of 1 second from 6.30.2 Operation, PCI Spec r6.0 */
@@ -662,3 +664,72 @@ int pci_doe(struct pci_doe_mb *doe_mb, u16 vendor, u8 type,
 	return task.rv;
 }
 EXPORT_SYMBOL_GPL(pci_doe);
+
+/**
+ * pci_find_doe_mailbox() - Find Data Object Exchange mailbox
+ *
+ * @pdev: PCI device
+ * @vendor: Vendor ID
+ * @type: Data Object Type
+ *
+ * Find first DOE mailbox of a PCI device which supports the given protocol.
+ *
+ * RETURNS: Pointer to the DOE mailbox or NULL if none was found.
+ */
+struct pci_doe_mb *pci_find_doe_mailbox(struct pci_dev *pdev, u16 vendor,
+					u8 type)
+{
+	struct pci_doe_mb *doe_mb;
+	unsigned long index;
+
+	xa_for_each(&pdev->doe_mbs, index, doe_mb)
+		if (pci_doe_supports_prot(doe_mb, vendor, type))
+			return doe_mb;
+
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(pci_find_doe_mailbox);
+
+void pci_doe_init(struct pci_dev *pdev)
+{
+	struct pci_doe_mb *doe_mb;
+	u16 offset = 0;
+	int rc;
+
+	xa_init(&pdev->doe_mbs);
+
+	while ((offset = pci_find_next_ext_capability(pdev, offset,
+						      PCI_EXT_CAP_ID_DOE))) {
+		doe_mb = pci_doe_create_mb(pdev, offset);
+		if (IS_ERR(doe_mb))
+			continue;
+
+		rc = xa_insert(&pdev->doe_mbs, offset, doe_mb, GFP_KERNEL);
+		if (rc) {
+			pci_doe_flush_mb(doe_mb);
+			pci_doe_destroy_mb(doe_mb);
+			pci_err(pdev, "[%x] failed to insert mailbox: %d\n",
+				offset, rc);
+		}
+	}
+}
+
+void pci_doe_stop(struct pci_dev *pdev)
+{
+	struct pci_doe_mb *doe_mb;
+	unsigned long index;
+
+	xa_for_each(&pdev->doe_mbs, index, doe_mb)
+		pci_doe_flush_mb(doe_mb);
+}
+
+void pci_doe_destroy(struct pci_dev *pdev)
+{
+	struct pci_doe_mb *doe_mb;
+	unsigned long index;
+
+	xa_for_each(&pdev->doe_mbs, index, doe_mb)
+		pci_doe_destroy_mb(doe_mb);
+
+	xa_destroy(&pdev->doe_mbs);
+}
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 9ed3b5550043..94656c1a01c0 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -777,6 +777,16 @@ static inline pci_power_t mid_pci_get_power_state(struct pci_dev *pdev)
 }
 #endif
 
+#ifdef CONFIG_PCI_DOE
+void pci_doe_init(struct pci_dev *pdev);
+void pci_doe_stop(struct pci_dev *pdev);
+void pci_doe_destroy(struct pci_dev *pdev);
+#else
+static inline void pci_doe_init(struct pci_dev *pdev) { }
+static inline void pci_doe_stop(struct pci_dev *pdev) { }
+static inline void pci_doe_destroy(struct pci_dev *pdev) { }
+#endif
+
 /*
  * Config Address for PCI Configuration Mechanism #1
  *
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 1779582fb500..65e60ee50489 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -2476,6 +2476,7 @@ static void pci_init_capabilities(struct pci_dev *dev)
 	pci_aer_init(dev);		/* Advanced Error Reporting */
 	pci_dpc_init(dev);		/* Downstream Port Containment */
 	pci_rcec_init(dev);		/* Root Complex Event Collector */
+	pci_doe_init(dev);		/* Data Object Exchange */
 
 	pcie_report_downtraining(dev);
 	pci_init_reset_methods(dev);
diff --git a/drivers/pci/remove.c b/drivers/pci/remove.c
index 0145aef1b930..739c7b0f5b91 100644
--- a/drivers/pci/remove.c
+++ b/drivers/pci/remove.c
@@ -16,6 +16,7 @@ static void pci_free_resources(struct pci_dev *dev)
 
 static void pci_stop_dev(struct pci_dev *dev)
 {
+	pci_doe_stop(dev);
 	pci_pme_active(dev, false);
 
 	if (pci_dev_is_added(dev)) {
@@ -39,6 +40,7 @@ static void pci_destroy_dev(struct pci_dev *dev)
 	list_del(&dev->bus_list);
 	up_write(&pci_bus_sem);
 
+	pci_doe_destroy(dev);
 	pcie_aspm_exit_link_state(dev);
 	pci_bridge_d3_update(dev);
 	pci_free_resources(dev);
diff --git a/include/linux/pci-doe.h b/include/linux/pci-doe.h
index 7f16749c6aa3..d6192ee0ac07 100644
--- a/include/linux/pci-doe.h
+++ b/include/linux/pci-doe.h
@@ -29,6 +29,8 @@ struct pci_doe_mb;
 
 struct pci_doe_mb *pcim_doe_create_mb(struct pci_dev *pdev, u16 cap_offset);
 bool pci_doe_supports_prot(struct pci_doe_mb *doe_mb, u16 vid, u8 type);
+struct pci_doe_mb *pci_find_doe_mailbox(struct pci_dev *pdev, u16 vendor,
+					u8 type);
 
 int pci_doe(struct pci_doe_mb *doe_mb, u16 vendor, u8 type,
 	    const void *request, size_t request_sz,
diff --git a/include/linux/pci.h b/include/linux/pci.h
index adffd65e84b4..254c79f9013a 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -511,6 +511,9 @@ struct pci_dev {
 #endif
 #ifdef CONFIG_PCI_P2PDMA
 	struct pci_p2pdma __rcu *p2pdma;
+#endif
+#ifdef CONFIG_PCI_DOE
+	struct xarray	doe_mbs;	/* Data Object Exchange mailboxes */
 #endif
 	u16		acs_cap;	/* ACS Capability offset */
 	phys_addr_t	rom;		/* Physical address if not from BAR */
-- 
2.39.1

