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Subject[PATCH v3 09/10] vfio/pci: Intel IGD host and LCP bridge config space access
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Provide read-only access to PCI config space of the PCI host bridge
and LPC bridge through device specific regions. This may be used to
configure a VM with matching register contents to satisfy driver
requirements. Providing this through the vfio file descriptor removes
an additional userspace requirement for access through pci-sysfs and
removes the CAP_SYS_ADMIN requirement that doesn't appear to apply to
the specific devices we're accessing.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
---
drivers/vfio/pci/vfio_pci.c | 15 ++-
drivers/vfio/pci/vfio_pci_igd.c | 171 +++++++++++++++++++++++++++++++++++
drivers/vfio/pci/vfio_pci_private.h | 4 -
include/uapi/linux/vfio.h | 3 +
4 files changed, 186 insertions(+), 7 deletions(-)

diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
index cb2624d..74a3752 100644
--- a/drivers/vfio/pci/vfio_pci.c
+++ b/drivers/vfio/pci/vfio_pci.c
@@ -111,6 +111,7 @@ static inline bool vfio_pci_is_vga(struct pci_dev *pdev)
}

static void vfio_pci_try_bus_reset(struct vfio_pci_device *vdev);
+static void vfio_pci_disable(struct vfio_pci_device *vdev);

static int vfio_pci_enable(struct vfio_pci_device *vdev)
{
@@ -170,10 +171,16 @@ static int vfio_pci_enable(struct vfio_pci_device *vdev)
vdev->has_vga = true;


- if (vfio_pci_is_vga(pdev) && pdev->vendor == PCI_VENDOR_ID_INTEL) {
- if (vfio_pci_igd_opregion_init(vdev) == 0)
- dev_info(&pdev->dev,
- "Intel IGD OpRegion support enabled\n");
+ if (vfio_pci_is_vga(pdev) &&
+ pdev->vendor == PCI_VENDOR_ID_INTEL &&
+ IS_ENABLED(CONFIG_VFIO_PCI_IGD)) {
+ ret = vfio_pci_igd_init(vdev);
+ if (ret) {
+ dev_warn(&vdev->pdev->dev,
+ "Failed to setup Intel IGD regions\n");
+ vfio_pci_disable(vdev);
+ return ret;
+ }
}

return 0;
diff --git a/drivers/vfio/pci/vfio_pci_igd.c b/drivers/vfio/pci/vfio_pci_igd.c
index 3b6a6f7..6394b16 100644
--- a/drivers/vfio/pci/vfio_pci_igd.c
+++ b/drivers/vfio/pci/vfio_pci_igd.c
@@ -55,7 +55,7 @@ static const struct vfio_pci_regops vfio_pci_igd_regops = {
.release = vfio_pci_igd_release,
};

-int vfio_pci_igd_opregion_init(struct vfio_pci_device *vdev)
+static int vfio_pci_igd_opregion_init(struct vfio_pci_device *vdev)
{
__le32 *dwordp = (__le32 *)(vdev->vconfig + OPREGION_PCI_ADDR);
u32 addr, size;
@@ -109,3 +109,172 @@ int vfio_pci_igd_opregion_init(struct vfio_pci_device *vdev)

return ret;
}
+
+static size_t vfio_pci_igd_cfg_rw(struct vfio_pci_device *vdev,
+ char __user *buf, size_t count, loff_t *ppos,
+ bool iswrite)
+{
+ unsigned int i = VFIO_PCI_OFFSET_TO_INDEX(*ppos) - VFIO_PCI_NUM_REGIONS;
+ struct pci_dev *pdev = vdev->region[i].data;
+ loff_t pos = *ppos & VFIO_PCI_OFFSET_MASK;
+ size_t size;
+ int ret;
+
+ if (pos >= vdev->region[i].size || iswrite)
+ return -EINVAL;
+
+ size = count = min(count, (size_t)(vdev->region[i].size - pos));
+
+ if ((pos & 1) && size) {
+ u8 val;
+
+ ret = pci_user_read_config_byte(pdev, pos, &val);
+ if (ret)
+ return pcibios_err_to_errno(ret);
+
+ if (copy_to_user(buf + count - size, &val, 1))
+ return -EFAULT;
+
+ pos++;
+ size--;
+ }
+
+ if ((pos & 3) && size > 2) {
+ u16 val;
+
+ ret = pci_user_read_config_word(pdev, pos, &val);
+ if (ret)
+ return pcibios_err_to_errno(ret);
+
+ val = cpu_to_le16(val);
+ if (copy_to_user(buf + count - size, &val, 2))
+ return -EFAULT;
+
+ pos += 2;
+ size -= 2;
+ }
+
+ while (size > 3) {
+ u32 val;
+
+ ret = pci_user_read_config_dword(pdev, pos, &val);
+ if (ret)
+ return pcibios_err_to_errno(ret);
+
+ val = cpu_to_le32(val);
+ if (copy_to_user(buf + count - size, &val, 4))
+ return -EFAULT;
+
+ pos += 4;
+ size -= 4;
+ }
+
+ while (size >= 2) {
+ u16 val;
+
+ ret = pci_user_read_config_word(pdev, pos, &val);
+ if (ret)
+ return pcibios_err_to_errno(ret);
+
+ val = cpu_to_le16(val);
+ if (copy_to_user(buf + count - size, &val, 2))
+ return -EFAULT;
+
+ pos += 2;
+ size -= 2;
+ }
+
+ while (size) {
+ u8 val;
+
+ ret = pci_user_read_config_byte(pdev, pos, &val);
+ if (ret)
+ return pcibios_err_to_errno(ret);
+
+ if (copy_to_user(buf + count - size, &val, 1))
+ return -EFAULT;
+
+ pos++;
+ size--;
+ }
+
+ *ppos += count;
+
+ return count;
+}
+
+static void vfio_pci_igd_cfg_release(struct vfio_pci_device *vdev,
+ struct vfio_pci_region *region)
+{
+ struct pci_dev *pdev = region->data;
+
+ pci_dev_put(pdev);
+}
+
+static const struct vfio_pci_regops vfio_pci_igd_cfg_regops = {
+ .rw = vfio_pci_igd_cfg_rw,
+ .release = vfio_pci_igd_cfg_release,
+};
+
+static int vfio_pci_igd_cfg_init(struct vfio_pci_device *vdev)
+{
+ struct pci_dev *host_bridge, *lpc_bridge;
+ int ret;
+
+ host_bridge = pci_get_domain_bus_and_slot(0, 0, PCI_DEVFN(0, 0));
+ if (!host_bridge)
+ return -ENODEV;
+
+ if (host_bridge->vendor != PCI_VENDOR_ID_INTEL ||
+ host_bridge->class != (PCI_CLASS_BRIDGE_HOST << 8)) {
+ pci_dev_put(host_bridge);
+ return -EINVAL;
+ }
+
+ ret = vfio_pci_register_dev_region(vdev,
+ PCI_VENDOR_ID_INTEL | VFIO_REGION_TYPE_PCI_VENDOR_TYPE,
+ VFIO_REGION_SUBTYPE_INTEL_IGD_HOST_CFG,
+ &vfio_pci_igd_cfg_regops, host_bridge->cfg_size,
+ VFIO_REGION_INFO_FLAG_READ, host_bridge);
+ if (ret) {
+ pci_dev_put(host_bridge);
+ return ret;
+ }
+
+ lpc_bridge = pci_get_domain_bus_and_slot(0, 0, PCI_DEVFN(0x1f, 0));
+ if (!lpc_bridge)
+ return -ENODEV;
+
+ if (lpc_bridge->vendor != PCI_VENDOR_ID_INTEL ||
+ lpc_bridge->class != (PCI_CLASS_BRIDGE_ISA << 8)) {
+ pci_dev_put(lpc_bridge);
+ return -EINVAL;
+ }
+
+ ret = vfio_pci_register_dev_region(vdev,
+ PCI_VENDOR_ID_INTEL | VFIO_REGION_TYPE_PCI_VENDOR_TYPE,
+ VFIO_REGION_SUBTYPE_INTEL_IGD_LPC_CFG,
+ &vfio_pci_igd_cfg_regops, lpc_bridge->cfg_size,
+ VFIO_REGION_INFO_FLAG_READ, lpc_bridge);
+ if (ret) {
+ pci_dev_put(lpc_bridge);
+ return ret;
+ }
+
+ return 0;
+}
+
+int vfio_pci_igd_init(struct vfio_pci_device *vdev)
+{
+ int ret;
+
+ ret = vfio_pci_igd_opregion_init(vdev);
+ if (ret)
+ return ret;
+
+ ret = vfio_pci_igd_cfg_init(vdev);
+ if (ret)
+ return ret;
+
+ return 0;
+}
diff --git a/drivers/vfio/pci/vfio_pci_private.h b/drivers/vfio/pci/vfio_pci_private.h
index 19f7699..8a7d546 100644
--- a/drivers/vfio/pci/vfio_pci_private.h
+++ b/drivers/vfio/pci/vfio_pci_private.h
@@ -123,9 +123,9 @@ extern int vfio_pci_register_dev_region(struct vfio_pci_device *vdev,
const struct vfio_pci_regops *ops,
size_t size, u32 flags, void *data);
#ifdef CONFIG_VFIO_PCI_IGD
-extern int vfio_pci_igd_opregion_init(struct vfio_pci_device *vdev);
+extern int vfio_pci_igd_init(struct vfio_pci_device *vdev);
#else
-static inline int vfio_pci_igd_opregion_init(struct vfio_pci_device *vdev)
+static inline int vfio_pci_igd_init(struct vfio_pci_device *vdev)
{
return -ENODEV;
}
diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
index e622982..255a211 100644
--- a/include/uapi/linux/vfio.h
+++ b/include/uapi/linux/vfio.h
@@ -283,7 +283,10 @@ struct vfio_region_info_cap_type {
#define VFIO_REGION_TYPE_PCI_VENDOR_TYPE (1 << 31)
#define VFIO_REGION_TYPE_PCI_VENDOR_MASK (0xffff)

+/* 8086 Vendor sub-types */
#define VFIO_REGION_SUBTYPE_INTEL_IGD_OPREGION (1)
+#define VFIO_REGION_SUBTYPE_INTEL_IGD_HOST_CFG (2)
+#define VFIO_REGION_SUBTYPE_INTEL_IGD_LPC_CFG (3)

/**
* VFIO_DEVICE_GET_IRQ_INFO - _IOWR(VFIO_TYPE, VFIO_BASE + 9,
\
 
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