Merge tag 'powerpc-4.11-2' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux

Pull more powerpc updates from Michael Ellerman:
 "Highlights include:

   - an update of the disassembly code used by xmon to the latest
     versions in binutils. We've received permission from all the
     authors of the relevant binutils changes to relicense their changes
     to the relevant files from GPLv3 to GPLv2, for inclusion in Linux.
     Thanks to Peter Bergner for doing the leg work to get permission
     from everyone.

   - addition of the "architected" Power9 CPU table entry, allowing us
     to boot in Power9 architected mode under a hypervisor.

   - updates to the Power9 PMU code.

   - implementation of clear_bit_unlock_is_negative_byte() to optimise
     unlock_page().

   - Freescale updates from Scott: "Highlights include 8xx breakpoints
     and perf, t1042rdb display support, and board updates."

  Thanks to:
    Al Viro, Andrew Donnellan, Aneesh Kumar K.V, Balbir Singh, Douglas
    Miller, Frédéric Weisbecker, Gavin Shan, Madhavan Srinivasan,
    Michael Roth, Nathan Fontenot, Naveen N. Rao, Nicholas Piggin, Peter
    Bergner, Paul E. McKenney, Rashmica Gupta, Russell Currey, Sahil
    Mehta, Stewart Smith"

* tag 'powerpc-4.11-2' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (48 commits)
  powerpc: Remove leftover cputime_to_nsecs call causing build error
  powerpc/mm/hash: Always clear UPRT and Host Radix bits when setting up CPU
  powerpc/optprobes: Fix TOC handling in optprobes trampoline
  powerpc/pseries: Advertise Hot Plug Event support to firmware
  cxl: fix nested locking hang during EEH hotplug
  powerpc/xmon: Dump memory in CPU endian format
  powerpc/pseries: Revert 'Auto-online hotplugged memory'
  powerpc/powernv: Make PCI non-optional
  powerpc/64: Implement clear_bit_unlock_is_negative_byte()
  powerpc/powernv: Remove unused variable in pnv_pci_sriov_disable()
  powerpc/kernel: Remove error message in pcibios_setup_phb_resources()
  powerpc/mm: Fix typo in set_pte_at()
  pci/hotplug/pnv-php: Disable MSI and PCI device properly
  pci/hotplug/pnv-php: Disable surprise hotplug capability on conflicts
  pci/hotplug/pnv-php: Remove WARN_ON() in pnv_php_put_slot()
  powerpc: Add POWER9 architected mode to cputable
  powerpc/perf: use is_kernel_addr macro in perf_get_misc_flags()
  powerpc/perf: Avoid FAB_*_MATCH checks for power9
  powerpc/perf: Add restrictions to PMC5 in power9 DD1
  powerpc/perf: Use Instruction Counter value
  ...

4 files changed, 27 insertions, 10 deletions

diff --git a/drivers/misc/cxl/cxl.h b/drivers/misc/cxl/cxl.h
index 6c722d96b775d..79e60ec70bd39 100644
--- a/drivers/misc/cxl/cxl.h
+++ b/drivers/misc/cxl/cxl.h
@@ -418,8 +418,9 @@ 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;
+
+	/* -1: AFU deconfigured/locked, >= 0: number of readers */
+	atomic_t configured_state;
 
 	/* 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 2a6bf1d0a3a4f..cc1706a92aceb 100644
--- a/drivers/misc/cxl/main.c
+++ b/drivers/misc/cxl/main.c
@@ -268,8 +268,7 @@ 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);
+	atomic_set(&afu->configured_state, -1);
 	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 cca938845ffdd..91f645992c941 100644
--- a/drivers/misc/cxl/pci.c
+++ b/drivers/misc/cxl/pci.c
@@ -1129,7 +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);
+	atomic_set(&afu->configured_state, 0);
 	return 0;
 
 err2:
@@ -1142,7 +1142,14 @@ err1:
 
 static void pci_deconfigure_afu(struct cxl_afu *afu)
 {
-	down_write(&afu->configured_rwsem);
+	/*
+	 * It's okay to deconfigure when AFU is already locked, otherwise wait
+	 * until there are no readers
+	 */
+	if (atomic_read(&afu->configured_state) != -1) {
+		while (atomic_cmpxchg(&afu->configured_state, 0, -1) != -1)
+			schedule();
+	}
 	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 639a343b7836a..512a4897dbf6e 100644
--- a/drivers/misc/cxl/vphb.c
+++ b/drivers/misc/cxl/vphb.c
@@ -83,6 +83,16 @@ static inline struct cxl_afu *pci_bus_to_afu(struct pci_bus *bus)
 	return phb ? phb->private_data : NULL;
 }
 
+static void cxl_afu_configured_put(struct cxl_afu *afu)
+{
+	atomic_dec_if_positive(&afu->configured_state);
+}
+
+static bool cxl_afu_configured_get(struct cxl_afu *afu)
+{
+	return atomic_inc_unless_negative(&afu->configured_state);
+}
+
 static inline int cxl_pcie_config_info(struct pci_bus *bus, unsigned int devfn,
 				       struct cxl_afu *afu, int *_record)
 {
@@ -107,7 +117,7 @@ static int cxl_pcie_read_config(struct pci_bus *bus, unsigned int devfn,
 
 	afu = pci_bus_to_afu(bus);
 	/* Grab a reader lock on afu. */
-	if (afu == NULL || !down_read_trylock(&afu->configured_rwsem))
+	if (afu == NULL || !cxl_afu_configured_get(afu))
 		return PCIBIOS_DEVICE_NOT_FOUND;
 
 	rc = cxl_pcie_config_info(bus, devfn, afu, &record);
@@ -132,7 +142,7 @@ static int cxl_pcie_read_config(struct pci_bus *bus, unsigned int devfn,
 	}
 
 out:
-	up_read(&afu->configured_rwsem);
+	cxl_afu_configured_put(afu);
 	return rc ? PCIBIOS_DEVICE_NOT_FOUND : PCIBIOS_SUCCESSFUL;
 }
 
@@ -144,7 +154,7 @@ static int cxl_pcie_write_config(struct pci_bus *bus, unsigned int devfn,
 
 	afu = pci_bus_to_afu(bus);
 	/* Grab a reader lock on afu. */
-	if (afu == NULL || !down_read_trylock(&afu->configured_rwsem))
+	if (afu == NULL || !cxl_afu_configured_get(afu))
 		return PCIBIOS_DEVICE_NOT_FOUND;
 
 	rc = cxl_pcie_config_info(bus, devfn, afu, &record);
@@ -166,7 +176,7 @@ static int cxl_pcie_write_config(struct pci_bus *bus, unsigned int devfn,
 	}
 
 out:
-	up_read(&afu->configured_rwsem);
+	cxl_afu_configured_put(afu);
 	return rc ? PCIBIOS_SET_FAILED : PCIBIOS_SUCCESSFUL;
 }