[RFC PATCH v1 05/38] tsm: Don't overload connect

["Aneesh Kumar K.V (Arm)" <aneesh.kumar@kernel.org>]

We need separate handling in the guest while destroying the device.
Hence switch to new callback lock and unlock. Hide the connect sysfs
file in guest.

guest sysfs will now looks like
ls -al  /sys/bus/pci/devices/0000:02:00.0/tsm/
total 0
drwxr-xr-x    2 root     root             0 Jan  1 00:00 .
drwxr-xr-x    7 root     root             0 Jan  1 00:00 ..
-rw-r--r--    1 root     root          4096 Jan  1 00:00 accept
-rw-r--r--    1 root     root          4096 Jan  1 00:00 lock

Signed-off-by: Aneesh Kumar K.V (Arm) <aneesh.kumar@kernel.org>
---
 drivers/pci/tsm.c       | 136 ++++++++++++++++++++++++++++++++++------
 include/linux/pci-tsm.h |   3 +
 2 files changed, 121 insertions(+), 18 deletions(-)

diff --git a/drivers/pci/tsm.c b/drivers/pci/tsm.c
index 60f50d57a725..80607082b7f0 100644
--- a/drivers/pci/tsm.c
+++ b/drivers/pci/tsm.c
@@ -125,18 +125,6 @@ static int pci_tsm_disconnect(struct pci_dev *pdev)
 	return 0;
 }
 
-/*
- * TDISP locked state temporarily makes the device inaccessible, do not
- * surprise live attached drivers
- */
-static int __driver_idle_connect(struct pci_dev *pdev)
-{
-	guard(device)(&pdev->dev);
-	if (pdev->dev.driver)
-		return -EBUSY;
-	return tsm_ops->connect(pdev);
-}
-
 /*
  * When the registered ops support accept it indicates that this is a
  * TVM-side (guest) TSM operations structure. In this mode ->connect()
@@ -162,10 +150,7 @@ static int pci_tsm_connect(struct pci_dev *pdev)
 	if (tsm->state >= PCI_TSM_CONNECT)
 		return 0;
 
-	if (tvm_mode())
-		rc = __driver_idle_connect(pdev);
-	else
-		rc = tsm_ops->connect(pdev);
+	rc = tsm_ops->connect(pdev);
 	if (rc)
 		return rc;
 	tsm->state = PCI_TSM_CONNECT;
@@ -299,6 +284,99 @@ static ssize_t accept_show(struct device *dev, struct device_attribute *attr,
 }
 static DEVICE_ATTR_RW(accept);
 
+static int pci_tsm_unlock(struct pci_dev *pdev)
+{
+	struct pci_tsm_pf0 *tsm = to_pci_tsm_pf0(pdev->tsm);
+
+	struct mutex *lock __free(tsm_ops_unlock) = tsm_ops_lock(tsm);
+	if (!lock)
+		return -EINTR;
+
+	if (tsm->state < PCI_TSM_INIT)
+		return -ENXIO;
+	if (tsm->state < PCI_TSM_LOCK)
+		return 0;
+
+	tsm_ops->unlock(pdev);
+	tsm->state = PCI_TSM_INIT;
+	pdev->dev.tdi_enabled = false;
+
+	return 0;
+}
+
+/*
+ * TDISP locked state temporarily makes the device inaccessible, do not
+ * surprise live attached drivers
+ */
+static int __driver_idle_lock(struct pci_dev *pdev)
+{
+	guard(device)(&pdev->dev);
+	if (pdev->dev.driver)
+		return -EBUSY;
+	return tsm_ops->lock(pdev);
+}
+
+static int pci_tsm_lock(struct pci_dev *pdev)
+{
+	struct pci_tsm_pf0 *tsm = to_pci_tsm_pf0(pdev->tsm);
+	int rc;
+
+	struct mutex *lock __free(tsm_ops_unlock) = tsm_ops_lock(tsm);
+	if (!lock)
+		return -EINTR;
+
+	if (tsm->state < PCI_TSM_INIT)
+		return -ENXIO;
+
+	rc = __driver_idle_lock(pdev);
+	if (rc)
+		return rc;
+	tsm->state = PCI_TSM_CONNECT;
+	return 0;
+}
+
+static ssize_t lock_store(struct device *dev, struct device_attribute *attr,
+			  const char *buf, size_t len)
+{
+	int rc;
+	bool connect;
+	struct pci_dev *pdev = to_pci_dev(dev);
+
+	rc = kstrtobool(buf, &connect);
+	if (rc)
+		return rc;
+
+	struct rw_semaphore *lock __free(tsm_read_unlock) = tsm_read_lock();
+	if (!lock)
+		return -EINTR;
+
+	if (connect)
+		rc = pci_tsm_lock(pdev);
+	else
+		rc = pci_tsm_unlock(pdev);
+	if (rc)
+		return rc;
+	return len;
+}
+
+static ssize_t lock_show(struct device *dev, struct device_attribute *attr,
+			 char *buf)
+{
+	struct pci_dev *pdev = to_pci_dev(dev);
+	struct pci_tsm_pf0 *tsm;
+
+	struct rw_semaphore *lock __free(tsm_read_unlock) = tsm_read_lock();
+	if (!lock)
+		return -EINTR;
+
+	if (!pdev->tsm)
+		return -ENXIO;
+
+	tsm = to_pci_tsm_pf0(pdev->tsm);
+	return sysfs_emit(buf, "%d\n", tsm->state >= PCI_TSM_LOCK);
+}
+static DEVICE_ATTR_RW(lock);
+
 static umode_t pci_tsm_pf0_attr_visible(struct kobject *kobj,
 					struct attribute *a, int n)
 {
@@ -306,6 +384,11 @@ static umode_t pci_tsm_pf0_attr_visible(struct kobject *kobj,
 		/* Host context, filter out guest only attributes */
 		if (a == &dev_attr_accept.attr)
 			return 0;
+		if (a == &dev_attr_lock.attr)
+			return 0;
+	} else {
+		if (a == &dev_attr_connect.attr)
+			return 0;
 	}
 
 	return a->mode;
@@ -325,6 +408,7 @@ DEFINE_SYSFS_GROUP_VISIBLE(pci_tsm_pf0);
 static struct attribute *pci_tsm_pf0_attrs[] = {
 	&dev_attr_connect.attr,
 	&dev_attr_accept.attr,
+	&dev_attr_lock.attr,
 	NULL
 };
 
@@ -537,7 +621,8 @@ static void pci_tsm_pf0_init(struct pci_dev *pdev)
 		return;
 
 	pdev->tsm = no_free_ptr(pci_tsm);
-	sysfs_update_group(&pdev->dev.kobj, &pci_tsm_auth_attr_group);
+	if (!tvm_mode())
+		sysfs_update_group(&pdev->dev.kobj, &pci_tsm_auth_attr_group);
 	sysfs_update_group(&pdev->dev.kobj, &pci_tsm_pf0_attr_group);
 	if (pci_tsm_owner_attr_group)
 		sysfs_merge_group(&pdev->dev.kobj, pci_tsm_owner_attr_group);
@@ -602,6 +687,19 @@ static void pci_tsm_pf0_destroy(struct pci_dev *pdev)
 	__pci_tsm_pf0_destroy(tsm);
 }
 
+static void pci_tsm_guest_destroy(struct pci_dev *pdev)
+{
+	struct pci_tsm_pf0 *tsm = to_pci_tsm_pf0(pdev->tsm);
+
+	if (tsm->state > PCI_TSM_INIT)
+		pci_tsm_unlock(pdev);
+	pdev->tsm = NULL;
+	if (pci_tsm_owner_attr_group)
+		sysfs_unmerge_group(&pdev->dev.kobj, pci_tsm_owner_attr_group);
+	sysfs_update_group(&pdev->dev.kobj, &pci_tsm_pf0_attr_group);
+	__pci_tsm_pf0_destroy(tsm);
+}
+
 static void __pci_tsm_destroy(struct pci_dev *pdev)
 {
 	struct pci_tsm *pci_tsm = pdev->tsm;
@@ -611,7 +709,9 @@ static void __pci_tsm_destroy(struct pci_dev *pdev)
 
 	lockdep_assert_held_write(&pci_tsm_rwsem);
 
-	if (is_pci_tsm_pf0(pdev)) {
+	if (tvm_mode()) {
+		pci_tsm_guest_destroy(pdev);
+	} else if (is_pci_tsm_pf0(pdev)) {
 		pci_tsm_pf0_destroy(pdev);
 	} else {
 		__pci_tsm_unbind(pdev);
diff --git a/include/linux/pci-tsm.h b/include/linux/pci-tsm.h
index 0d4303726b25..7639e7963681 100644
--- a/include/linux/pci-tsm.h
+++ b/include/linux/pci-tsm.h
@@ -11,6 +11,7 @@ enum pci_tsm_state {
 	PCI_TSM_ERR = -1,
 	PCI_TSM_INIT,
 	PCI_TSM_CONNECT,
+	PCI_TSM_LOCK,
 	PCI_TSM_ACCEPT,
 };
 
@@ -153,6 +154,8 @@ struct pci_tsm_ops {
 	void (*remove)(struct pci_tsm *tsm);
 	int (*connect)(struct pci_dev *pdev);
 	void (*disconnect)(struct pci_dev *pdev);
+	int (*lock)(struct pci_dev *pdev);
+	void (*unlock)(struct pci_dev *pdev);
 	struct pci_tdi *(*bind)(struct pci_dev *pdev, struct pci_dev *pf0_dev,
 				struct kvm *kvm, u64 tdi_id);
 	void (*unbind)(struct pci_tdi *tdi);
-- 
2.43.0