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vfio-pci: Add module option to disable VGA region access 

Add a module option so that we don't require a CONFIG change and
kernel rebuild to disable VGA support.  Not only can VGA support be
troublesome in itself, but by disabling it we can reduce the impact
to host devices by doing a VGA arbitration opt-out.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
This commit is contained in:
Alex Williamson 2015-04-07 11:14:40 -06:00
parent 0ea18b40cd
commit 88c0dead9f
1 changed files with 16 additions and 3 deletions
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19
drivers/vfio/pci/vfio_pci.c
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@ -37,8 +37,23 @@ module_param_named(nointxmask, nointxmask, bool, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(nointxmask,
"Disable support for PCI 2.3 style INTx masking. If this resolves problems for specific devices, report lspci -vvvxxx to linux-pci@vger.kernel.org so the device can be fixed automatically via the broken_intx_masking flag.");
#ifdef CONFIG_VFIO_PCI_VGA
static bool disable_vga;
module_param(disable_vga, bool, S_IRUGO);
MODULE_PARM_DESC(disable_vga, "Disable VGA resource access through vfio-pci");
#endif
static DEFINE_MUTEX(driver_lock);
static inline bool vfio_vga_disabled(void)
{
#ifdef CONFIG_VFIO_PCI_VGA
return disable_vga;
#else
return true;
#endif
}
static void vfio_pci_try_bus_reset(struct vfio_pci_device *vdev);
static int vfio_pci_enable(struct vfio_pci_device *vdev)
@ -93,10 +108,8 @@ static int vfio_pci_enable(struct vfio_pci_device *vdev)
} else
vdev->msix_bar = 0xFF;
#ifdef CONFIG_VFIO_PCI_VGA
if ((pdev->class >> 8) == PCI_CLASS_DISPLAY_VGA)
if (!vfio_vga_disabled() && (pdev->class >> 8) == PCI_CLASS_DISPLAY_VGA)
vdev->has_vga = true;
#endif
return 0;
}