Previously BAR resource requests and the corresponding pci_iomap()
were performed on-demand and without synchronisation, which was racy.
Rather than add synchronisation, it's simplest to address this by
doing both activities from vfio_pci_core_enable().
The resource allocation and/or pci_iomap() can still fail; their
status is tracked and existing calls to vfio_pci_core_setup_barmap()
will fail in a similar way to before. This keeps the point of failure
as observed by userspace the same, i.e. failures to request/map unused
BARs are benign.
Fixes: 7f5764e179c6 ("vfio: use vfio_pci_core_setup_barmap to map bar in mmap")
Fixes: 0d77ed3589ac0 ("vfio/pci: Pull BAR mapping setup from read-write path")
Signed-off-by: Matt Evans <[email protected]>
---
drivers/vfio/pci/vfio_pci_core.c | 33 ++++++++++++++++++++++++++++++++
drivers/vfio/pci/vfio_pci_rdwr.c | 29 ++++++++++++----------------
2 files changed, 45 insertions(+), 17 deletions(-)
diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_core.c
index 3f8d093aacf8..eab4f2626b39 100644
--- a/drivers/vfio/pci/vfio_pci_core.c
+++ b/drivers/vfio/pci/vfio_pci_core.c
@@ -482,6 +482,38 @@ static int vfio_pci_core_runtime_resume(struct device *dev)
}
#endif /* CONFIG_PM */
+static void vfio_pci_core_map_bars(struct vfio_pci_core_device *vdev)
+{
+ struct pci_dev *pdev = vdev->pdev;
+ int i;
+
+ /*
+ * Eager-request BAR resources, and iomap. Soft failures are
+ * allowed, and consumers must check the barmap before use in
+ * order to give compatible user-visible behaviour with the
+ * previous on-demand allocation method.
+ */
+ for (i = 0; i < PCI_STD_NUM_BARS; i++) {
+ int bar = i + PCI_STD_RESOURCES;
+ void __iomem *io = ERR_PTR(-ENODEV);
+
+ if (pci_resource_len(pdev, i) > 0) {
+ if (pci_request_selected_regions(pdev, 1 << bar,
"vfio")) {
+ pci_warn(vdev->pdev, "Failed to reserve region
%d\n", bar);
+ io = ERR_PTR(-EBUSY);
+ } else {
+ io = pci_iomap(pdev, bar, 0);
+ if (!io) {
+ pci_warn(vdev->pdev, "Failed to iomap
region %d\n",
+ bar);
+ io = ERR_PTR(-ENOMEM);
+ }
+ }
+ }
+ vdev->barmap[bar] = io;
+ }
+}
+
/*
* The pci-driver core runtime PM routines always save the device state
* before going into suspended state. If the device is going into low power
@@ -568,6 +600,7 @@ int vfio_pci_core_enable(struct vfio_pci_core_device *vdev)
if (!vfio_vga_disabled() && vfio_pci_is_vga(pdev))
vdev->has_vga = true;
+ vfio_pci_core_map_bars(vdev);
return 0;
diff --git a/drivers/vfio/pci/vfio_pci_rdwr.c b/drivers/vfio/pci/vfio_pci_rdwr.c
index 4251ee03e146..f66ad3d96481 100644
--- a/drivers/vfio/pci/vfio_pci_rdwr.c
+++ b/drivers/vfio/pci/vfio_pci_rdwr.c
@@ -200,25 +200,20 @@ EXPORT_SYMBOL_GPL(vfio_pci_core_do_io_rw);
int vfio_pci_core_setup_barmap(struct vfio_pci_core_device *vdev, int bar)
{
- struct pci_dev *pdev = vdev->pdev;
- int ret;
- void __iomem *io;
-
- if (vdev->barmap[bar])
- return 0;
-
- ret = pci_request_selected_regions(pdev, 1 << bar, "vfio");
- if (ret)
- return ret;
-
- io = pci_iomap(pdev, bar, 0);
- if (!io) {
- pci_release_selected_regions(pdev, 1 << bar);
- return -ENOMEM;
- }
+ /*
+ * The barmap is set up in vfio_pci_core_enable(). Callers
+ * use this function to check that the BAR resources are
+ * requested or that the pci_iomap() was done.
+ */
+ if (bar < 0 || bar >= PCI_STD_NUM_BARS)
+ return -EINVAL;
- vdev->barmap[bar] = io;
+ /* Did vfio_pci_core_map_bars() set it up yet? */
+ if (!vdev->barmap[bar])
+ return -ENODEV;
+ if (IS_ERR(vdev->barmap[bar]))
+ return PTR_ERR(vdev->barmap[bar]);
return 0;
}
EXPORT_SYMBOL_GPL(vfio_pci_core_setup_barmap);
--
2.47.3
