Message-ID: <alpine.DEB.2.20.1707030943000.2188@nanos>
Date:   Mon, 3 Jul 2017 09:50:35 +0200 (CEST)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
cc:     LKML <linux-kernel@...r.kernel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Ingo Molnar <mingo@...nel.org>,
        "H. Peter Anvin" <hpa@...or.com>
Subject: [GIT pull] x86/PCI updates for 4.13

Linus,

please pull the latest x86-platform-for-linus git tree from:

   git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git x86-platform-for-linus

This update provides:

   The seperation of x86 PCI accessors from the global PCI lock in the
   generic PCI config space accessors.  The reasons for this are:

   - x86 has it's own PCI config lock for various reasons, so the accessors
     have to lock two locks nested.

   - The ECAM (mmconfig) access to the extended configuration space does
     not require locking. The existing generic locking causes a massive
     lock contention when accessing the extended config space of the Uncore
     facility for performance monitoring.

   The commit, which switched the access to the primary config space over
   to ECAM mode, has been removed from the branch, so the primary config
   space is still accessed with type1 accessors properly serialized by the
   x86 internal locking.

   Bjorn agreed on merging this through the x86 tree.

Thanks,

	tglx

------------------>
Thomas Gleixner (5):
      x86/PCI: Remove duplicate defines
      x86/PCI: Abort if legacy init fails
      x86/PCI/ce4100: Properly lock accessor functions
      PCI: Provide Kconfig option for lockless config space accessors
      x86/PCI: Select CONFIG_PCI_LOCKLESS_CONFIG


 arch/x86/Kconfig           |  1 +
 arch/x86/include/asm/pci.h |  8 +----
 arch/x86/pci/ce4100.c      | 87 +++++++++++++++++++++++++---------------------
 arch/x86/pci/common.c      |  4 +--
 arch/x86/pci/legacy.c      | 18 +++++-----
 drivers/pci/Kconfig        |  3 ++
 drivers/pci/access.c       | 16 ++++++---
 7 files changed, 77 insertions(+), 60 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 0efb4c9497bc..0652c9f8902e 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -166,6 +166,7 @@ config X86
 	select HAVE_UNSTABLE_SCHED_CLOCK
 	select HAVE_USER_RETURN_NOTIFIER
 	select IRQ_FORCED_THREADING
+	select PCI_LOCKLESS_CONFIG
 	select PERF_EVENTS
 	select RTC_LIB
 	select RTC_MC146818_LIB
diff --git a/arch/x86/include/asm/pci.h b/arch/x86/include/asm/pci.h
index f513cc231151..473a7295ab10 100644
--- a/arch/x86/include/asm/pci.h
+++ b/arch/x86/include/asm/pci.h
@@ -77,14 +77,8 @@ static inline bool is_vmd(struct pci_bus *bus)
 
 extern unsigned int pcibios_assign_all_busses(void);
 extern int pci_legacy_init(void);
-# ifdef CONFIG_ACPI
-#  define x86_default_pci_init pci_acpi_init
-# else
-#  define x86_default_pci_init pci_legacy_init
-# endif
 #else
-# define pcibios_assign_all_busses()	0
-# define x86_default_pci_init		NULL
+static inline int pcibios_assign_all_busses(void) { return 0; }
 #endif
 
 extern unsigned long pci_mem_start;
diff --git a/arch/x86/pci/ce4100.c b/arch/x86/pci/ce4100.c
index b914e20b5a00..3353b76dcff0 100644
--- a/arch/x86/pci/ce4100.c
+++ b/arch/x86/pci/ce4100.c
@@ -65,6 +65,9 @@ struct sim_reg_op {
 { PCI_DEVFN(device, func), offset, init_op, read_op, write_op,\
 	{0, SIZE_TO_MASK(size)} },
 
+/*
+ * All read/write functions are called with pci_config_lock held.
+ */
 static void reg_init(struct sim_dev_reg *reg)
 {
 	pci_direct_conf1.read(0, 1, reg->dev_func, reg->reg, 4,
@@ -73,21 +76,13 @@ static void reg_init(struct sim_dev_reg *reg)
 
 static void reg_read(struct sim_dev_reg *reg, u32 *value)
 {
-	unsigned long flags;
-
-	raw_spin_lock_irqsave(&pci_config_lock, flags);
 	*value = reg->sim_reg.value;
-	raw_spin_unlock_irqrestore(&pci_config_lock, flags);
 }
 
 static void reg_write(struct sim_dev_reg *reg, u32 value)
 {
-	unsigned long flags;
-
-	raw_spin_lock_irqsave(&pci_config_lock, flags);
 	reg->sim_reg.value = (value & reg->sim_reg.mask) |
 		(reg->sim_reg.value & ~reg->sim_reg.mask);
-	raw_spin_unlock_irqrestore(&pci_config_lock, flags);
 }
 
 static void sata_reg_init(struct sim_dev_reg *reg)
@@ -117,12 +112,8 @@ static void sata_revid_read(struct sim_dev_reg *reg, u32 *value)
 
 static void reg_noirq_read(struct sim_dev_reg *reg, u32 *value)
 {
-	unsigned long flags;
-
-	raw_spin_lock_irqsave(&pci_config_lock, flags);
 	/* force interrupt pin value to 0 */
 	*value = reg->sim_reg.value & 0xfff00ff;
-	raw_spin_unlock_irqrestore(&pci_config_lock, flags);
 }
 
 static struct sim_dev_reg bus1_fixups[] = {
@@ -265,24 +256,33 @@ int bridge_read(unsigned int devfn, int reg, int len, u32 *value)
 	return retval;
 }
 
-static int ce4100_conf_read(unsigned int seg, unsigned int bus,
-			    unsigned int devfn, int reg, int len, u32 *value)
+static int ce4100_bus1_read(unsigned int devfn, int reg, int len, u32 *value)
 {
+	unsigned long flags;
 	int i;
 
-	WARN_ON(seg);
-	if (bus == 1) {
-		for (i = 0; i < ARRAY_SIZE(bus1_fixups); i++) {
-			if (bus1_fixups[i].dev_func == devfn &&
-			    bus1_fixups[i].reg == (reg & ~3) &&
-			    bus1_fixups[i].read) {
-				bus1_fixups[i].read(&(bus1_fixups[i]),
-						    value);
-				extract_bytes(value, reg, len);
-				return 0;
-			}
+	for (i = 0; i < ARRAY_SIZE(bus1_fixups); i++) {
+		if (bus1_fixups[i].dev_func == devfn &&
+		    bus1_fixups[i].reg == (reg & ~3) &&
+		    bus1_fixups[i].read) {
+
+			raw_spin_lock_irqsave(&pci_config_lock, flags);
+			bus1_fixups[i].read(&(bus1_fixups[i]), value);
+			raw_spin_unlock_irqrestore(&pci_config_lock, flags);
+			extract_bytes(value, reg, len);
+			return 0;
 		}
 	}
+	return -1;
+}
+
+static int ce4100_conf_read(unsigned int seg, unsigned int bus,
+			    unsigned int devfn, int reg, int len, u32 *value)
+{
+	WARN_ON(seg);
+
+	if (bus == 1 && !ce4100_bus1_read(devfn, reg, len, value))
+		return 0;
 
 	if (bus == 0 && (PCI_DEVFN(1, 0) == devfn) &&
 	    !bridge_read(devfn, reg, len, value))
@@ -291,23 +291,32 @@ static int ce4100_conf_read(unsigned int seg, unsigned int bus,
 	return pci_direct_conf1.read(seg, bus, devfn, reg, len, value);
 }
 
-static int ce4100_conf_write(unsigned int seg, unsigned int bus,
-			     unsigned int devfn, int reg, int len, u32 value)
+static int ce4100_bus1_write(unsigned int devfn, int reg, int len, u32 value)
 {
+	unsigned long flags;
 	int i;
 
-	WARN_ON(seg);
-	if (bus == 1) {
-		for (i = 0; i < ARRAY_SIZE(bus1_fixups); i++) {
-			if (bus1_fixups[i].dev_func == devfn &&
-			    bus1_fixups[i].reg == (reg & ~3) &&
-			    bus1_fixups[i].write) {
-				bus1_fixups[i].write(&(bus1_fixups[i]),
-						     value);
-				return 0;
-			}
+	for (i = 0; i < ARRAY_SIZE(bus1_fixups); i++) {
+		if (bus1_fixups[i].dev_func == devfn &&
+		    bus1_fixups[i].reg == (reg & ~3) &&
+		    bus1_fixups[i].write) {
+
+			raw_spin_lock_irqsave(&pci_config_lock, flags);
+			bus1_fixups[i].write(&(bus1_fixups[i]), value);
+			raw_spin_unlock_irqrestore(&pci_config_lock, flags);
+			return 0;
 		}
 	}
+	return -1;
+}
+
+static int ce4100_conf_write(unsigned int seg, unsigned int bus,
+			     unsigned int devfn, int reg, int len, u32 value)
+{
+	WARN_ON(seg);
+
+	if (bus == 1 && !ce4100_bus1_write(devfn, reg, len, value))
+		return 0;
 
 	/* Discard writes to A/V bridge BAR. */
 	if (bus == 0 && PCI_DEVFN(1, 0) == devfn &&
@@ -318,8 +327,8 @@ static int ce4100_conf_write(unsigned int seg, unsigned int bus,
 }
 
 static const struct pci_raw_ops ce4100_pci_conf = {
-	.read =	ce4100_conf_read,
-	.write = ce4100_conf_write,
+	.read	= ce4100_conf_read,
+	.write	= ce4100_conf_write,
 };
 
 int __init ce4100_pci_init(void)
diff --git a/arch/x86/pci/common.c b/arch/x86/pci/common.c
index 190e718694b1..cfd1a89fd04e 100644
--- a/arch/x86/pci/common.c
+++ b/arch/x86/pci/common.c
@@ -75,8 +75,8 @@ struct pci_ops pci_root_ops = {
 };
 
 /*
- * This interrupt-safe spinlock protects all accesses to PCI
- * configuration space.
+ * This interrupt-safe spinlock protects all accesses to PCI configuration
+ * space, except for the mmconfig (ECAM) based operations.
  */
 DEFINE_RAW_SPINLOCK(pci_config_lock);
 
diff --git a/arch/x86/pci/legacy.c b/arch/x86/pci/legacy.c
index ea6f3802c17b..1cb01abcb1be 100644
--- a/arch/x86/pci/legacy.c
+++ b/arch/x86/pci/legacy.c
@@ -24,12 +24,10 @@ static void pcibios_fixup_peer_bridges(void)
 
 int __init pci_legacy_init(void)
 {
-	if (!raw_pci_ops) {
-		printk("PCI: System does not support PCI\n");
-		return 0;
-	}
+	if (!raw_pci_ops)
+		return 1;
 
-	printk("PCI: Probing PCI hardware\n");
+	pr_info("PCI: Probing PCI hardware\n");
 	pcibios_scan_root(0);
 	return 0;
 }
@@ -46,7 +44,7 @@ void pcibios_scan_specific_bus(int busn)
 		if (!raw_pci_read(0, busn, devfn, PCI_VENDOR_ID, 2, &l) &&
 		    l != 0x0000 && l != 0xffff) {
 			DBG("Found device at %02x:%02x [%04x]\n", busn, devfn, l);
-			printk(KERN_INFO "PCI: Discovered peer bus %02x\n", busn);
+			pr_info("PCI: Discovered peer bus %02x\n", busn);
 			pcibios_scan_root(busn);
 			return;
 		}
@@ -60,8 +58,12 @@ static int __init pci_subsys_init(void)
 	 * The init function returns an non zero value when
 	 * pci_legacy_init should be invoked.
 	 */
-	if (x86_init.pci.init())
-		pci_legacy_init();
+	if (x86_init.pci.init()) {
+		if (pci_legacy_init()) {
+			pr_info("PCI: System does not support PCI\n");
+			return -ENODEV;
+		}
+	}
 
 	pcibios_fixup_peer_bridges();
 	x86_init.pci.init_irq();
diff --git a/drivers/pci/Kconfig b/drivers/pci/Kconfig
index e0cacb7b8563..c32a77fc8b03 100644
--- a/drivers/pci/Kconfig
+++ b/drivers/pci/Kconfig
@@ -86,6 +86,9 @@ config PCI_ATS
 config PCI_ECAM
 	bool
 
+config PCI_LOCKLESS_CONFIG
+	bool
+
 config PCI_IOV
 	bool "PCI IOV support"
 	depends on PCI
diff --git a/drivers/pci/access.c b/drivers/pci/access.c
index c80e37a69305..913d6722ece9 100644
--- a/drivers/pci/access.c
+++ b/drivers/pci/access.c
@@ -25,6 +25,14 @@ DEFINE_RAW_SPINLOCK(pci_lock);
 #define PCI_word_BAD (pos & 1)
 #define PCI_dword_BAD (pos & 3)
 
+#ifdef CONFIG_PCI_LOCKLESS_CONFIG
+# define pci_lock_config(f)	do { (void)(f); } while (0)
+# define pci_unlock_config(f)	do { (void)(f); } while (0)
+#else
+# define pci_lock_config(f)	raw_spin_lock_irqsave(&pci_lock, f)
+# define pci_unlock_config(f)	raw_spin_unlock_irqrestore(&pci_lock, f)
+#endif
+
 #define PCI_OP_READ(size, type, len) \
 int pci_bus_read_config_##size \
 	(struct pci_bus *bus, unsigned int devfn, int pos, type *value)	\
@@ -33,10 +41,10 @@ int pci_bus_read_config_##size \
 	unsigned long flags;						\
 	u32 data = 0;							\
 	if (PCI_##size##_BAD) return PCIBIOS_BAD_REGISTER_NUMBER;	\
-	raw_spin_lock_irqsave(&pci_lock, flags);			\
+	pci_lock_config(flags);						\
 	res = bus->ops->read(bus, devfn, pos, len, &data);		\
 	*value = (type)data;						\
-	raw_spin_unlock_irqrestore(&pci_lock, flags);		\
+	pci_unlock_config(flags);					\
 	return res;							\
 }
 
@@ -47,9 +55,9 @@ int pci_bus_write_config_##size \
 	int res;							\
 	unsigned long flags;						\
 	if (PCI_##size##_BAD) return PCIBIOS_BAD_REGISTER_NUMBER;	\
-	raw_spin_lock_irqsave(&pci_lock, flags);			\
+	pci_lock_config(flags);						\
 	res = bus->ops->write(bus, devfn, pos, len, value);		\
-	raw_spin_unlock_irqrestore(&pci_lock, flags);		\
+	pci_unlock_config(flags);					\
 	return res;							\
 }
 

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