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

[Yongji Xie]

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

> > --
> > 1.7.9.5