Current vfio-pci implementation disallows to mmap MSI-X
table in case that user get to touch this directly.
However, EEH mechanism can ensure that a given pci device
can only shoot the MSIs assigned for its PE. So we think
it's safe to expose the MSI-X table to userspace because
the exposed MSI-X table can't be used to do harm to other
memory space.
And with MSI-X table mmapped, some performance issues which
are caused when PCI adapters have critical registers in the
same page as the MSI-X table also can be resolved.
So this patch adds a Kconfig option, VFIO_PCI_MMAP_MSIX,
to support for mmapping MSI-X table.
Signed-off-by: Yongji Xie <xyj...@linux.vnet.ibm.com>
---
drivers/vfio/pci/Kconfig | 4 ++++
drivers/vfio/pci/vfio_pci.c | 6 ++++--
2 files changed, 8 insertions(+), 2 deletions(-)
diff --git a/drivers/vfio/pci/Kconfig b/drivers/vfio/pci/Kconfig
index 02912f1..67b0a2c 100644
--- a/drivers/vfio/pci/Kconfig
+++ b/drivers/vfio/pci/Kconfig
@@ -23,6 +23,10 @@ config VFIO_PCI_MMAP
depends on VFIO_PCI
def_bool y if !S390
+config VFIO_PCI_MMAP_MSIX
+ depends on VFIO_PCI_MMAP
+ def_bool y if EEH
+
config VFIO_PCI_INTX
depends on VFIO_PCI
def_bool y if !S390
diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
index 09b3805..d536985 100644
--- a/drivers/vfio/pci/vfio_pci.c
+++ b/drivers/vfio/pci/vfio_pci.c
@@ -555,7 +555,8 @@ static long vfio_pci_ioctl(void *device_data,
IORESOURCE_MEM && (info.size >= PAGE_SIZE ||
pci_resource_page_aligned)) {
info.flags |= VFIO_REGION_INFO_FLAG_MMAP;
- if (info.index == vdev->msix_bar) {
+ if (!IS_ENABLED(CONFIG_VFIO_PCI_MMAP_MSIX) &&
+ info.index == vdev->msix_bar) {
ret = msix_sparse_mmap_cap(vdev, &caps);
if (ret)
return ret;
@@ -967,7 +968,8 @@ static int vfio_pci_mmap(void *device_data, struct
vm_area_struct *vma)
if (phys_len < PAGE_SIZE || req_start + req_len > phys_len)
return -EINVAL;
- if (index == vdev->msix_bar) {
+ if (!IS_ENABLED(CONFIG_VFIO_PCI_MMAP_MSIX) &&
+ index == vdev->msix_bar) {
/*
* Disallow mmaps overlapping the MSI-X table; users don't
* get to touch this directly. We could find somewhere
--
1.7.9.5
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