[PATCH v3 11/21] PCI/TSM: Support connecting to PCIe CMA devices

[alistair23@gmail.com]

From: Alistair Francis <alistair.francis@wdc.com>

In the next patch we are going to add a PCIe CMA TSM driver, as such we
need to ensure that is_pci_tsm_host() will allow us to connect to CMA
capable devices. These devices don't necessarily has DEVCAP_TEE or IDE
support.

To avoid calling pci_find_doe_mailbox() everytime is_pci_tsm_host() is
called we can cache the CMA support in struct pci_dev and just check
against that.

Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
---
 drivers/pci/doe.c       |  3 +++
 drivers/pci/tsm.c       | 31 +++++++++++++++++++++++++------
 include/linux/pci-tsm.h | 12 +++++++++++-
 include/linux/pci.h     |  1 +
 4 files changed, 40 insertions(+), 7 deletions(-)

diff --git a/drivers/pci/doe.c b/drivers/pci/doe.c
index ac95b1d2d999..6a59969bd52f 100644
--- a/drivers/pci/doe.c
+++ b/drivers/pci/doe.c
@@ -870,6 +870,9 @@ void pci_doe_init(struct pci_dev *pdev)
 			pci_doe_destroy_mb(doe_mb);
 		}
 	}
+
+	pdev->doe_cma = pci_find_doe_mailbox(pdev, PCI_VENDOR_ID_PCI_SIG,
+					     PCI_DOE_FEATURE_CMA);
 }
 
 void pci_doe_destroy(struct pci_dev *pdev)
diff --git a/drivers/pci/tsm.c b/drivers/pci/tsm.c
index 10c9c6696624..440f818ac569 100644
--- a/drivers/pci/tsm.c
+++ b/drivers/pci/tsm.c
@@ -88,8 +88,8 @@ static void pci_tsm_walk_fns(struct pci_dev *pdev,
 		if (!pf)
 			continue;
 
-		/* on entry function 0 has already run @cb */
-		if (i > 0)
+		/* the caller is responsible for running @cb on the host itself */
+		if (pf != pdev)
 			cb(pf, data);
 
 		/* walk virtual functions of each pf */
@@ -145,8 +145,8 @@ static void pci_tsm_walk_fns_reverse(struct pci_dev *pdev,
 			cb(vf, data);
 		}
 
-		/* on exit, caller will run @cb on function 0 */
-		if (i > 0)
+		/* the caller is responsible for running @cb on the host itself */
+		if (pf != pdev)
 			cb(pf, data);
 	}
 }
@@ -287,6 +287,16 @@ static DEVICE_ATTR_RW(connect);
 
 static int remove_fn(struct pci_dev *pdev, void *data)
 {
+	struct pci_dev *host = data;
+
+	/*
+	 * Only teardown the security context of functions that belong to the
+	 * DSM being disconnected, leaving any sibling DSM in the same slot
+	 * untouched.
+	 */
+	if (!pdev->tsm || pdev->tsm->dsm_dev != host)
+		return 0;
+
 	tsm_remove(pdev->tsm);
 	link_sysfs_disable(pdev);
 	return 0;
@@ -299,6 +309,7 @@ static int remove_fn(struct pci_dev *pdev, void *data)
  */
 static int __pci_tsm_unbind(struct pci_dev *pdev, void *data)
 {
+	struct pci_dev *host = data;
 	struct pci_tdi *tdi;
 	struct pci_tsm_host *tsm_host;
 
@@ -307,6 +318,14 @@ static int __pci_tsm_unbind(struct pci_dev *pdev, void *data)
 	if (!pdev->tsm)
 		return 0;
 
+	/*
+	 * When walking a DSM's dependent functions skip any that belong to a
+	 * different DSM in the same slot. A NULL @host is a direct unbind of
+	 * @pdev itself.
+	 */
+	if (host && pdev->tsm->dsm_dev != host)
+		return 0;
+
 	tsm_host = to_pci_tsm_host(pdev->tsm);
 	guard(mutex)(&tsm_host->lock);
 
@@ -437,7 +456,7 @@ EXPORT_SYMBOL_GPL(pci_tsm_guest_req);
 
 static void pci_tsm_unbind_all(struct pci_dev *pdev)
 {
-	pci_tsm_walk_fns_reverse(pdev, __pci_tsm_unbind, NULL);
+	pci_tsm_walk_fns_reverse(pdev, __pci_tsm_unbind, pdev);
 	__pci_tsm_unbind(pdev, NULL);
 }
 
@@ -456,7 +475,7 @@ static void __pci_tsm_disconnect(struct pci_dev *pdev)
 	 * teardown
 	 */
 	guard(mutex)(&tsm_host->lock);
-	pci_tsm_walk_fns_reverse(pdev, remove_fn, NULL);
+	pci_tsm_walk_fns_reverse(pdev, remove_fn, pdev);
 	ops->disconnect(pdev);
 }
 
diff --git a/include/linux/pci-tsm.h b/include/linux/pci-tsm.h
index 950e2c36a4ca..f504fa680315 100644
--- a/include/linux/pci-tsm.h
+++ b/include/linux/pci-tsm.h
@@ -3,6 +3,7 @@
 #define __PCI_TSM_H
 #include <linux/mutex.h>
 #include <linux/pci.h>
+#include <linux/pci-doe.h>
 #include <linux/sockptr.h>
 
 struct pci_tsm;
@@ -130,7 +131,7 @@ struct pci_tsm_host {
 	struct pci_doe_mb *doe_mb;
 };
 
-/* physical function0 and capable of 'connect' */
+/* device is a TSM host and capable of 'connect' */
 static inline bool is_pci_tsm_host(struct pci_dev *pdev)
 {
 	if (!pdev)
@@ -142,6 +143,15 @@ static inline bool is_pci_tsm_host(struct pci_dev *pdev)
 	if (pdev->is_virtfn)
 		return false;
 
+	/*
+	 * Report capable if CMA is supported, which can be supported on any PCIe
+	 * device.
+	 */
+#ifdef CONFIG_PCI_DOE
+	if (pdev->doe_cma)
+		return true;
+#endif
+
 	/*
 	 * Allow for a Device Security Manager (DSM) associated with function0
 	 * of an Endpoint to coordinate TDISP requests for other functions
diff --git a/include/linux/pci.h b/include/linux/pci.h
index d31a8d107b1e..cb13b40952b4 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -565,6 +565,7 @@ struct pci_dev {
 #endif
 #ifdef CONFIG_PCI_DOE
 	struct xarray	doe_mbs;	/* Data Object Exchange mailboxes */
+	bool		doe_cma;	/* A CMA/SPDM DOE mailbox is present */
 #endif
 #ifdef CONFIG_PCI_NPEM
 	struct npem	*npem;		/* Native PCIe Enclosure Management */
-- 
2.55.0