This series aims to add an option for PCI resource allocator to force BARs not to share PAGE_SIZE. This would make sense to VFIO driver. Because current VFIO implementation disallows to mmap sub-page(size < PAGE_SIZE) MMIO BARs which may share the same page with other BARs for security reasons. Thus, we have to handle mmio access to these BARs in QEMU emulation rather than in guest which will cause some performance loss. To achieve that, we would like to make use of the existing resource_alignment kernel parameter and force a minimum alignment of PAGE_SIZE. It's flexible. And we can enable it by default on some archs which may easily hit the performance issue because of their 64K page. In this series, patch 1,2,3 fixed bugs of using resource_alignment; patch 4,5 tried to add a new option for resource_alignment to use IORESOURCE_STARTALIGN to specify the alignment of PCI BARs; patch 6 modified resource_alignment to support syntax which can be used to enforce the alignment of all MMIO BARs to be at least PAGE_SIZE; patch 7 enabled this feature by default on PowerNV platform. Changelog v3: - Ignore enforced alignment to fixed BARs - Fix issue that disabling memory decoding when reassigning the alignment - Only enable default alignment on PowerNV platform Changelog v2: - Ignore enforced alignment to VF BARs on pci_reassigndev_resource_alignment() Yongji Xie (7): PCI: Ignore enforced alignment when kernel uses existing firmware setup PCI: Ignore enforced alignment to VF BARs PCI: Do not disable memory decoding in pci_reassigndev_resource_alignment() PCI: Add a new option for resource_alignment to reassign alignment PCI: Do not use IORESOURCE_STARTALIGN to identify bridge resources PCI: Add support for enforcing all MMIO BARs to be page aligned PCI: Add a macro to set default alignment for all PCI devices Documentation/kernel-parameters.txt | 7 +- arch/powerpc/include/asm/pci.h | 4 ++ drivers/pci/pci.c | 123 +++++++++++++++++++++++++++-------- drivers/pci/setup-bus.c | 9 ++- 4 files changed, 111 insertions(+), 32 deletions(-) -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
