linux-kernel - [patch 0/7] x86/pci: Switch to lockless ECAM configuration mode

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Date:   Thu, 16 Mar 2017 22:50:02 +0100
From:   Thomas Gleixner <tglx@...utronix.de>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     Bjorn Helgaas <helgaas@...nel.org>, x86@...nel.org,
        Peter Anvin <hpa@...or.com>, Borislav Petkov <bp@...en8.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Stephane Eranian <eranian@...gle.com>,
        Andi Kleen <ak@...ux.intel.com>
Subject: [patch 0/7] x86/pci: Switch to lockless ECAM configuration mode

Andi reported that the Intel Uncore performance monitoring suffers from the
global pci_lock which protects the generic PCI config space accessors.

This lock can be removed on X86 because all architecture specific config
space accessors are either serialized by a seperate lock or can be
converted to have their own locking. The mmconfig based access (ECAM) does
not require serialization at the config read/write level because the access
is a simple byte/word/dword read from or write to the memory mapped
configuration space. In that case the lock does not provide any more
protection than the hardware provides already.

The series converts the CE4100 PCI low level accessors to use the x86
specific pci_config_lock and implements the switch over to lockless ECAM
configureation space accesors when the system is capable.

Thanks,

	tglx

---
 arch/x86/Kconfig               |    1 
 arch/x86/include/asm/pci.h     |    8 ---
 arch/x86/include/asm/pci_x86.h |   15 +++----
 arch/x86/pci/Makefile          |    2 
 arch/x86/pci/ce4100.c          |   87 ++++++++++++++++++++++-------------------
 arch/x86/pci/common.c          |   16 +++++++
 arch/x86/pci/legacy.c          |   19 +++++---
 arch/x86/pci/mmconfig-shared.c |   36 ++++++++++++++++
 arch/x86/pci/mmconfig_32.c     |   12 -----
 arch/x86/pci/mmconfig_64.c     |   16 +------
 drivers/pci/Kconfig            |    3 +
 drivers/pci/access.c           |   16 +++++--
 12 files changed, 142 insertions(+), 89 deletions(-)