When vfio passthroughs a PCI device of which MMIO BARs are smaller than PAGE_SIZE, guest will not handle the mmio accesses to the BARs which leads to mmio emulations in host. This is because vfio will not allow to passthrough one BAR's mmio page which may be shared with other BARs. Otherwise, there will be a backdoor that guest can use to access BARs of other guest. This patch adds a macro to set default alignment for all PCI devices. Then we could solve this issue on some platforms which would easily hit this issue because of their 64K page such as PowerNV platform by defining this macro as PAGE_SIZE. Signed-off-by: Yongji Xie <xyjxie@xxxxxxxxxxxxxxxxxx> --- arch/powerpc/include/asm/pci.h | 4 ++++ drivers/pci/pci.c | 3 +++ 2 files changed, 7 insertions(+), 0 deletions(-) diff --git a/arch/powerpc/include/asm/pci.h b/arch/powerpc/include/asm/pci.h index e9bd6cf..5e31bc2 100644 --- a/arch/powerpc/include/asm/pci.h +++ b/arch/powerpc/include/asm/pci.h @@ -28,6 +28,10 @@ #define PCIBIOS_MIN_IO 0x1000 #define PCIBIOS_MIN_MEM 0x10000000 +#ifdef CONFIG_PPC_POWERNV +#define PCIBIOS_DEFAULT_ALIGNMENT PAGE_SIZE +#endif + struct pci_dev; /* Values for the `which' argument to sys_pciconfig_iobase syscall. */ diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index a881c0d..2622e9b 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -4965,6 +4965,9 @@ static resource_size_t pci_specified_resource_alignment(struct pci_dev *dev) resource_size_t align = 0; char *p; +#ifdef PCIBIOS_DEFAULT_ALIGNMENT + align = PCIBIOS_DEFAULT_ALIGNMENT; +#endif spin_lock(&resource_alignment_lock); p = resource_alignment_param; if (!*p) -- 1.7.1
