4 files changed, 35 insertions, 23 deletions

diff --git a/drivers/misc/cxl/cxl.h b/drivers/misc/cxl/cxl.h
index b24d76723fb0..b4a43fd14b99 100644
--- a/drivers/misc/cxl/cxl.h
+++ b/drivers/misc/cxl/cxl.h
@@ -418,6 +418,8 @@ struct cxl_afu {
 	struct dentry *debugfs;
 	struct mutex contexts_lock;
 	spinlock_t afu_cntl_lock;
+	/* Used to block access to AFU config space while deconfigured */
+	struct rw_semaphore configured_rwsem;
 
 	/* AFU error buffer fields and bin attribute for sysfs */
 	u64 eb_len, eb_offset;
diff --git a/drivers/misc/cxl/main.c b/drivers/misc/cxl/main.c
index 62e0dfb5f15b..2a6bf1d0a3a4 100644
--- a/drivers/misc/cxl/main.c
+++ b/drivers/misc/cxl/main.c
@@ -268,7 +268,8 @@ struct cxl_afu *cxl_alloc_afu(struct cxl *adapter, int slice)
 	idr_init(&afu->contexts_idr);
 	mutex_init(&afu->contexts_lock);
 	spin_lock_init(&afu->afu_cntl_lock);
-
+	init_rwsem(&afu->configured_rwsem);
+	down_write(&afu->configured_rwsem);
 	afu->prefault_mode = CXL_PREFAULT_NONE;
 	afu->irqs_max = afu->adapter->user_irqs;
 
diff --git a/drivers/misc/cxl/pci.c b/drivers/misc/cxl/pci.c
index 73432e7d925d..cca938845ffd 100644
--- a/drivers/misc/cxl/pci.c
+++ b/drivers/misc/cxl/pci.c
@@ -1129,6 +1129,7 @@ static int pci_configure_afu(struct cxl_afu *afu, struct cxl *adapter, struct pc
 	if ((rc = cxl_native_register_psl_irq(afu)))
 		goto err2;
 
+	up_write(&afu->configured_rwsem);
 	return 0;
 
 err2:
@@ -1141,6 +1142,7 @@ err1:
 
 static void pci_deconfigure_afu(struct cxl_afu *afu)
 {
+	down_write(&afu->configured_rwsem);
 	cxl_native_release_psl_irq(afu);
 	if (afu->adapter->native->sl_ops->release_serr_irq)
 		afu->adapter->native->sl_ops->release_serr_irq(afu);
diff --git a/drivers/misc/cxl/vphb.c b/drivers/misc/cxl/vphb.c
index 3519acebfdab..639a343b7836 100644
--- a/drivers/misc/cxl/vphb.c
+++ b/drivers/misc/cxl/vphb.c
@@ -76,23 +76,22 @@ static int cxl_pcie_cfg_record(u8 bus, u8 devfn)
 	return (bus << 8) + devfn;
 }
 
-static int cxl_pcie_config_info(struct pci_bus *bus, unsigned int devfn,
-				struct cxl_afu **_afu, int *_record)
+static inline struct cxl_afu *pci_bus_to_afu(struct pci_bus *bus)
 {
-	struct pci_controller *phb;
-	struct cxl_afu *afu;
-	int record;
+	struct pci_controller *phb = bus ? pci_bus_to_host(bus) : NULL;
 
-	phb = pci_bus_to_host(bus);
-	if (phb == NULL)
-		return PCIBIOS_DEVICE_NOT_FOUND;
+	return phb ? phb->private_data : NULL;
+}
+
+static inline int cxl_pcie_config_info(struct pci_bus *bus, unsigned int devfn,
+				       struct cxl_afu *afu, int *_record)
+{
+	int record;
 
-	afu = (struct cxl_afu *)phb->private_data;
 	record = cxl_pcie_cfg_record(bus->number, devfn);
 	if (record > afu->crs_num)
 		return PCIBIOS_DEVICE_NOT_FOUND;
 
-	*_afu = afu;
 	*_record = record;
 	return 0;
 }
@@ -106,9 +105,14 @@ static int cxl_pcie_read_config(struct pci_bus *bus, unsigned int devfn,
 	u16 val16;
 	u32 val32;
 
-	rc = cxl_pcie_config_info(bus, devfn, &afu, &record);
+	afu = pci_bus_to_afu(bus);
+	/* Grab a reader lock on afu. */
+	if (afu == NULL || !down_read_trylock(&afu->configured_rwsem))
+		return PCIBIOS_DEVICE_NOT_FOUND;
+
+	rc = cxl_pcie_config_info(bus, devfn, afu, &record);
 	if (rc)
-		return rc;
+		goto out;
 
 	switch (len) {
 	case 1:
@@ -127,10 +131,9 @@ static int cxl_pcie_read_config(struct pci_bus *bus, unsigned int devfn,
 		WARN_ON(1);
 	}
 
-	if (rc)
-		return PCIBIOS_DEVICE_NOT_FOUND;
-
-	return PCIBIOS_SUCCESSFUL;
+out:
+	up_read(&afu->configured_rwsem);
+	return rc ? PCIBIOS_DEVICE_NOT_FOUND : PCIBIOS_SUCCESSFUL;
 }
 
 static int cxl_pcie_write_config(struct pci_bus *bus, unsigned int devfn,
@@ -139,9 +142,14 @@ static int cxl_pcie_write_config(struct pci_bus *bus, unsigned int devfn,
 	int rc, record;
 	struct cxl_afu *afu;
 
-	rc = cxl_pcie_config_info(bus, devfn, &afu, &record);
+	afu = pci_bus_to_afu(bus);
+	/* Grab a reader lock on afu. */
+	if (afu == NULL || !down_read_trylock(&afu->configured_rwsem))
+		return PCIBIOS_DEVICE_NOT_FOUND;
+
+	rc = cxl_pcie_config_info(bus, devfn, afu, &record);
 	if (rc)
-		return rc;
+		goto out;
 
 	switch (len) {
 	case 1:
@@ -157,10 +165,9 @@ static int cxl_pcie_write_config(struct pci_bus *bus, unsigned int devfn,
 		WARN_ON(1);
 	}
 
-	if (rc)
-		return PCIBIOS_SET_FAILED;
-
-	return PCIBIOS_SUCCESSFUL;
+out:
+	up_read(&afu->configured_rwsem);
+	return rc ? PCIBIOS_SET_FAILED : PCIBIOS_SUCCESSFUL;
 }
 
 static struct pci_ops cxl_pcie_pci_ops =