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: 89e1f7d4c66d ("vfio: Add PCI device driver")
Signed-off-by: Matt Evans <[email protected]>
---
drivers/vfio/pci/vfio_pci_core.c | 36 +++++++++++++++++++++++++++++++-
drivers/vfio/pci/vfio_pci_rdwr.c | 26 +++++++----------------
2 files changed, 42 insertions(+), 20 deletions(-)
diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_core.c
index 3f8d093aacf8..62931dc381d8 100644
--- a/drivers/vfio/pci/vfio_pci_core.c
+++ b/drivers/vfio/pci/vfio_pci_core.c
@@ -482,6 +482,39 @@ static int vfio_pci_core_runtime_resume(struct device *dev)
}
#endif /* CONFIG_PM */
+/*
+ * Eager-request BAR resources, and iomap them. 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.
+ */
+static void vfio_pci_core_map_bars(struct vfio_pci_core_device *vdev)
+{
+ struct pci_dev *pdev = vdev->pdev;
+ int i;
+
+ for (i = 0; i < PCI_STD_NUM_BARS; i++) {
+ int bar = i + PCI_STD_RESOURCES;
+
+ vdev->barmap[bar] = ERR_PTR(-ENODEV);
+
+ if (!pci_resource_len(pdev, i))
+ continue;
+
+ if (pci_request_selected_regions(pdev, 1 << bar, "vfio")) {
+ pci_dbg(vdev->pdev, "Failed to reserve region %d\n",
bar);
+ vdev->barmap[bar] = ERR_PTR(-EBUSY);
+ continue;
+ }
+
+ vdev->barmap[bar] = pci_iomap(pdev, bar, 0);
+ if (!vdev->barmap[bar]) {
+ pci_dbg(vdev->pdev, "Failed to iomap region %d\n", bar);
+ vdev->barmap[bar] = ERR_PTR(-ENOMEM);
+ }
+ }
+}
+
/*
* 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 +601,7 @@ 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;
@@ -648,7 +682,7 @@ void vfio_pci_core_disable(struct vfio_pci_core_device
*vdev)
for (i = 0; i < PCI_STD_NUM_BARS; i++) {
bar = i + PCI_STD_RESOURCES;
- if (!vdev->barmap[bar])
+ if (IS_ERR_OR_NULL(vdev->barmap[bar]))
continue;
pci_iounmap(pdev, vdev->barmap[bar]);
pci_release_selected_regions(pdev, 1 << bar);
diff --git a/drivers/vfio/pci/vfio_pci_rdwr.c b/drivers/vfio/pci/vfio_pci_rdwr.c
index 4251ee03e146..3bfbb879a005 100644
--- a/drivers/vfio/pci/vfio_pci_rdwr.c
+++ b/drivers/vfio/pci/vfio_pci_rdwr.c
@@ -198,27 +198,15 @@ ssize_t vfio_pci_core_do_io_rw(struct
vfio_pci_core_device *vdev, bool test_mem,
}
EXPORT_SYMBOL_GPL(vfio_pci_core_do_io_rw);
+/*
+ * 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.
+ */
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;
- }
-
- vdev->barmap[bar] = io;
-
+ 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
