PCI defines display class VGA regions at I/O port address 0x3b0, 0x3c0
and MMIO address 0xa0000. As these are non-overlapping, we can ignore
the I/O port vs MMIO difference and expose them both in a single
region. We make use of the VGA arbiter around each access to
configure chipset access as necessary.
Signed-off-by: Alex Williamson <alex.williamson@xxxxxxxxxx>
---
v2: Revise the region access based on VFIO AER discussion. We don't
need to add flags for everything or over-engineer generic legacy
resources. GET_REGION_INFO.num_regions should return the the highest
index, as the documentation specifies, not a count. Thus we always
return VFIO_PCI_NUM_REGIONS and userspace can probe for interesting
things within that. The existence of VFIO_PCI_VGA_REGION_INDEX
therefore indicates the presense of PCI VGA support and due to the VGA
I/O port and MMIO being non-overlapping, we can expose them in a
single region.
VFIO PCI AER can follow this lead for an IRQ and region for describing
AER events and data with VFIO_PCI_AER_IRQ_INDEX and
VFIO_PCI_AER_REGION_INDEX.
drivers/vfio/pci/Kconfig | 10 ++++++
drivers/vfio/pci/vfio_pci.c | 18 ++++++++++
drivers/vfio/pci/vfio_pci_private.h | 4 ++
drivers/vfio/pci/vfio_pci_rdwr.c | 61 +++++++++++++++++++++++++++++++++++
include/uapi/linux/vfio.h | 9 +++++
5 files changed, 102 insertions(+)
diff --git a/drivers/vfio/pci/Kconfig b/drivers/vfio/pci/Kconfig
index 5980758..e84300b 100644
--- a/drivers/vfio/pci/Kconfig
+++ b/drivers/vfio/pci/Kconfig
@@ -6,3 +6,13 @@ config VFIO_PCI
use of PCI drivers using the VFIO framework.
If you don't know what to do here, say N.
+
+config VFIO_PCI_VGA
+ bool "VFIO PCI support for VGA devices"
+ depends on VFIO_PCI && X86 && VGA_ARB && EXPERIMENTAL
+ help
+ Support for VGA extension to VFIO PCI. This exposes an additional
+ region on VGA devices for accessing legacy VGA addresses used by
+ BIOS and generic video drivers.
+
+ If you don't know what to do here, say N.
diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
index bb8c8c2..8189cb6 100644
--- a/drivers/vfio/pci/vfio_pci.c
+++ b/drivers/vfio/pci/vfio_pci.c
@@ -84,6 +84,11 @@ 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)
+ vdev->has_vga = true;
+#endif
+
return 0;
}
@@ -285,6 +290,16 @@ static long vfio_pci_ioctl(void *device_data,
info.flags = VFIO_REGION_INFO_FLAG_READ;
break;
}
+ case VFIO_PCI_VGA_REGION_INDEX:
+ if (!vdev->has_vga)
+ return -EINVAL;
+
+ info.offset = VFIO_PCI_INDEX_TO_OFFSET(info.index);
+ info.size = 0xc0000;
+ info.flags = VFIO_REGION_INFO_FLAG_READ |
+ VFIO_REGION_INFO_FLAG_WRITE;
+
+ break;
default:
return -EINVAL;
}
@@ -386,6 +401,9 @@ static ssize_t vfio_pci_rw(void *device_data, char __user *buf,
case VFIO_PCI_BAR0_REGION_INDEX ... VFIO_PCI_BAR5_REGION_INDEX:
return vfio_pci_bar_rw(vdev, buf, count, ppos, iswrite);
+
+ case VFIO_PCI_VGA_REGION_INDEX:
+ return vfio_pci_vga_rw(vdev, buf, count, ppos, iswrite);
}
return -EINVAL;
diff --git a/drivers/vfio/pci/vfio_pci_private.h b/drivers/vfio/pci/vfio_pci_private.h
index 00d19b9..d7e55d0 100644
--- a/drivers/vfio/pci/vfio_pci_private.h
+++ b/drivers/vfio/pci/vfio_pci_private.h
@@ -53,6 +53,7 @@ struct vfio_pci_device {
bool reset_works;
bool extended_caps;
bool bardirty;
+ bool has_vga;
struct pci_saved_state *pci_saved_state;
atomic_t refcnt;
};
@@ -77,6 +78,9 @@ extern ssize_t vfio_pci_config_rw(struct vfio_pci_device *vdev,
extern ssize_t vfio_pci_bar_rw(struct vfio_pci_device *vdev, char __user *buf,
size_t count, loff_t *ppos, bool iswrite);
+extern ssize_t vfio_pci_vga_rw(struct vfio_pci_device *vdev, char __user *buf,
+ size_t count, loff_t *ppos, bool iswrite);
+
extern int vfio_pci_init_perm_bits(void);
extern void vfio_pci_uninit_perm_bits(void);
diff --git a/drivers/vfio/pci/vfio_pci_rdwr.c b/drivers/vfio/pci/vfio_pci_rdwr.c
index e9d78eb..210db24 100644
--- a/drivers/vfio/pci/vfio_pci_rdwr.c
+++ b/drivers/vfio/pci/vfio_pci_rdwr.c
@@ -17,6 +17,7 @@
#include <linux/pci.h>
#include <linux/uaccess.h>
#include <linux/io.h>
+#include <linux/vgaarb.h>
#include "vfio_pci_private.h"
@@ -175,3 +176,63 @@ ssize_t vfio_pci_bar_rw(struct vfio_pci_device *vdev, char __user *buf,
return done;
}
+
+ssize_t vfio_pci_vga_rw(struct vfio_pci_device *vdev, char __user *buf,
+ size_t count, loff_t *ppos, bool iswrite)
+{
+ int ret;
+ loff_t off, pos = *ppos & VFIO_PCI_OFFSET_MASK;
+ void __iomem *iomem = NULL;
+ unsigned int rsrc;
+ bool is_ioport;
+ ssize_t done;
+
+ if (!vdev->has_vga)
+ return -EINVAL;
+
+ switch (pos) {
+ case 0xa0000 ... 0xbffff:
+ count = min(count, (size_t)(0xc0000 - pos));
+ iomem = ioremap_nocache(0xa0000, 0xbffff - 0xa0000 + 1);
+ off = pos - 0xa0000;
+ rsrc = VGA_RSRC_LEGACY_MEM;
+ is_ioport = false;
+ break;
+ case 0x3b0 ... 0x3bb:
+ count = min(count, (size_t)(0x3bc - pos));
+ iomem = ioport_map(0x3b0, 0x3bb - 0x3b0 + 1);
+ off = pos - 0x3b0;
+ rsrc = VGA_RSRC_LEGACY_IO;
+ is_ioport = true;
+ break;
+ case 0x3c0 ... 0x3df:
+ count = min(count, (size_t)(0x3e0 - pos));
+ iomem = ioport_map(0x3c0, 0x3df - 0x3c0 + 1);
+ off = pos - 0x3c0;
+ rsrc = VGA_RSRC_LEGACY_IO;
+ is_ioport = true;
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ if (!iomem)
+ return -ENOMEM;
+
+ ret = vga_get_interruptible(vdev->pdev, rsrc);
+ if (ret) {
+ is_ioport ? ioport_unmap(iomem) : iounmap(iomem);
+ return ret;
+ }
+
+ done = do_io_rw(iomem, buf, off, count, 0, 0, iswrite);
+
+ vga_put(vdev->pdev, rsrc);
+
+ is_ioport ? ioport_unmap(iomem) : iounmap(iomem);
+
+ if (done >= 0)
+ *ppos += done;
+
+ return done;
+}
diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
index 4758d1b..4f41f30 100644
--- a/include/uapi/linux/vfio.h
+++ b/include/uapi/linux/vfio.h
@@ -303,6 +303,15 @@ enum {
VFIO_PCI_BAR5_REGION_INDEX,
VFIO_PCI_ROM_REGION_INDEX,
VFIO_PCI_CONFIG_REGION_INDEX,
+ /*
+ * Expose VGA regions defined for PCI base class 03, subclass 00.
+ * This includes I/O port ranges 0x3b0 to 0x3bb and 0x3c0 to 0x3df
+ * as well as the MMIO range 0xa0000 to 0xbffff. Each implemented
+ * range is found at it's identity mapped offset from the region
+ * offset, for example 0x3b0 is region_info.offset + 0x3b0. Areas
+ * between described ranges are unimplemented.
+ */
+ VFIO_PCI_VGA_REGION_INDEX,
VFIO_PCI_NUM_REGIONS
};
--
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