Re: [RFC v5 7/7] vfio-pci: Allow to mmap MSI-X table if interrupt remapping is supported

From: Yongji Xie
Date: Tue Apr 05 2016 - 23:30:22 EST


On 2016/4/6 8:00, Gavin Shan wrote:
On Tue, Apr 05, 2016 at 09:46:44PM +0800, Yongji Xie wrote:
This patch enables mmapping MSI-X tables if
hardware supports interrupt remapping which
can ensure that a given pci device can only
shoot the MSIs assigned for it.

Signed-off-by: Yongji Xie <xyjxie@xxxxxxxxxxxxxxxxxx>
---
drivers/vfio/pci/vfio_pci.c | 9 +++++++--
drivers/vfio/pci/vfio_pci_private.h | 1 +
drivers/vfio/pci/vfio_pci_rdwr.c | 2 +-
3 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
index c60d790..ef02896 100644
--- a/drivers/vfio/pci/vfio_pci.c
+++ b/drivers/vfio/pci/vfio_pci.c
@@ -201,6 +201,10 @@ static int vfio_pci_enable(struct vfio_pci_device *vdev)
} else
vdev->msix_bar = 0xFF;

+ if (iommu_capable(pdev->dev.bus, IOMMU_CAP_INTR_REMAP) ||
+ pdev->bus->bus_flags | PCI_BUS_FLAGS_MSI_REMAP)
+ vdev->msi_remap = true;
+
I guess you probably need a "&" here. Otherwise, the condition
is always true.

Yes, you are right. I'll fix it.

if (!vfio_vga_disabled() && vfio_pci_is_vga(pdev))
vdev->has_vga = true;

@@ -635,7 +639,8 @@ static long vfio_pci_ioctl(void *device_data,
VFIO_REGION_INFO_FLAG_WRITE;
if (vdev->bar_mmap_supported[info.index]) {
info.flags |= VFIO_REGION_INFO_FLAG_MMAP;
- if (info.index == vdev->msix_bar) {
+ if (info.index == vdev->msix_bar &&
+ !vdev->msi_remap) {
ret = msix_sparse_mmap_cap(vdev, &caps);
if (ret)
return ret;
@@ -1067,7 +1072,7 @@ static int vfio_pci_mmap(void *device_data, struct vm_area_struct *vma)
if (req_start + req_len > phys_len)
return -EINVAL;

- if (index == vdev->msix_bar) {
+ if (index == vdev->msix_bar && !vdev->msi_remap) {
/*
* Disallow mmaps overlapping the MSI-X table; users don't
* get to touch this directly. We could find somewhere
diff --git a/drivers/vfio/pci/vfio_pci_private.h b/drivers/vfio/pci/vfio_pci_private.h
index 0ea4c62..4f20963 100644
--- a/drivers/vfio/pci/vfio_pci_private.h
+++ b/drivers/vfio/pci/vfio_pci_private.h
@@ -78,6 +78,7 @@ struct vfio_pci_device {
int irq_type;
int num_regions;
struct vfio_pci_region *region;
+ bool msi_remap;
u8 msi_qmax;
u8 msix_bar;
u16 msix_size;
diff --git a/drivers/vfio/pci/vfio_pci_rdwr.c b/drivers/vfio/pci/vfio_pci_rdwr.c
index 5ffd1d9..606ee3c 100644
--- a/drivers/vfio/pci/vfio_pci_rdwr.c
+++ b/drivers/vfio/pci/vfio_pci_rdwr.c
@@ -164,7 +164,7 @@ ssize_t vfio_pci_bar_rw(struct vfio_pci_device *vdev, char __user *buf,
} else
io = vdev->barmap[bar];

- if (bar == vdev->msix_bar) {
+ if (bar == vdev->msix_bar && !vdev->msi_remap) {
x_start = vdev->msix_offset;
x_end = vdev->msix_offset + vdev->msix_size;
}
When PCI_BUS_FLAGS_MSI_REMAP is set, the MSIx table can be accessed by
read/write interface except mmap(). The commit log doesn't mention it.
It would be better if you have some words about it.

Thanks,
Gavin


OK. I will mention it in commit log.

Thanks,
Yongji

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1.7.9.5