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 default to enable it on some archs which may easily hit the performance issue because of their 64K page. In this series, patch 1 fixed a bug of resource_alignment; patch 2,3 tried to add a new option for resource_alignment to use IORESOURCE_STARTALIGN to specify the alignment of PCI BARs; patch 4 modified resource_alignment to support syntax which can be used to enforce the alignment of all MMIO BARs to be at least PAGE_SIZE. Yongji Xie (4): PCI: Ignore resource_alignment if PCI_PROBE_ONLY was set PCI: Do not Use IORESOURCE_STARTALIGN to identify bridge resources PCI: Add a new option for resource_alignment to reassign alignment PCI: Add support for enforcing all MMIO BARs to be page aligned Documentation/kernel-parameters.txt | 7 ++- arch/powerpc/include/asm/pci.h | 2 + drivers/pci/pci.c | 105 ++++++++++++++++++++++++++++------- drivers/pci/setup-bus.c | 9 ++- 4 files changed, 98 insertions(+), 25 deletions(-) -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
