[PATCH 1/2] vfio/pci: Set up barmap in vfio_pci_core_enable()

[Matt Evans <mattev@meta.com>]

The previous lazy-setup of the barmaps provided opportunities to
forget to do it (for example, DMABUF export).  Since all users will
ultimately require BAR resources to have been requested, request them
in vfio_pci_core_enable.

Existing calls to vfio_pci_core_setup_barmap() are now benign, but
remain because some callers use it to validate a BAR index.  This
fixes at least the case where DMABUF export could succeed before
resources were requested.

This keeps resource request and ioremap() done at the same time, but
in future the ioremap() could be done on-demand (not all VFIO users
need it).

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 <mattev@meta.com>
---
 drivers/vfio/pci/vfio_pci_core.c | 63 +++++++++++++++++++++++++++-----
 drivers/vfio/pci/vfio_pci_rdwr.c | 25 +++----------
 2 files changed, 60 insertions(+), 28 deletions(-)

diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_core.c
index 3f8d093aacf8..4a314213f3ae 100644
--- a/drivers/vfio/pci/vfio_pci_core.c
+++ b/drivers/vfio/pci/vfio_pci_core.c
@@ -482,6 +482,55 @@ static int vfio_pci_core_runtime_resume(struct device *dev)
 }
 #endif /* CONFIG_PM */
 
+static void __vfio_pci_core_unmap_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;
+
+		if (!vdev->barmap[i])
+			continue;
+		pci_iounmap(pdev, vdev->barmap[bar]);
+		pci_release_selected_regions(pdev, 1 << bar);
+		vdev->barmap[bar] = NULL;
+	}
+}
+
+static int __vfio_pci_core_map_bars(struct vfio_pci_core_device *vdev)
+{
+	struct pci_dev *pdev = vdev->pdev;
+	int ret = 0;
+	int i;
+
+	/* Eager-request BAR resources (and iomap) */
+	for (i = 0; i < PCI_STD_NUM_BARS; i++) {
+		int bar = i + PCI_STD_RESOURCES;
+		void __iomem *io;
+
+		if (pci_resource_len(pdev, i) == 0)
+			continue;
+
+		ret = pci_request_selected_regions(pdev, 1 << bar, "vfio");
+		if (ret)
+			goto err_free_barmap;
+
+		io = pci_iomap(pdev, bar, 0);
+		if (!io) {
+			pci_release_selected_regions(pdev, 1 << bar);
+			ret = -ENOMEM;
+			goto err_free_barmap;
+		}
+		vdev->barmap[bar] = io;
+	}
+	return 0;
+
+err_free_barmap:
+	__vfio_pci_core_unmap_bars(vdev);
+	return ret;
+}
+
 /*
  * 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 +617,9 @@ int vfio_pci_core_enable(struct vfio_pci_core_device *vdev)
 	if (!vfio_vga_disabled() && vfio_pci_is_vga(pdev))
 		vdev->has_vga = true;
 
+	ret = __vfio_pci_core_map_bars(vdev);
+	if (ret)
+		goto out_free_zdev;
 
 	return 0;
 
@@ -591,7 +643,7 @@ void vfio_pci_core_disable(struct vfio_pci_core_device *vdev)
 	struct pci_dev *pdev = vdev->pdev;
 	struct vfio_pci_dummy_resource *dummy_res, *tmp;
 	struct vfio_pci_ioeventfd *ioeventfd, *ioeventfd_tmp;
-	int i, bar;
+	int i;
 
 	/* For needs_reset */
 	lockdep_assert_held(&vdev->vdev.dev_set->lock);
@@ -646,14 +698,7 @@ void vfio_pci_core_disable(struct vfio_pci_core_device *vdev)
 
 	vfio_config_free(vdev);
 
-	for (i = 0; i < PCI_STD_NUM_BARS; i++) {
-		bar = i + PCI_STD_RESOURCES;
-		if (!vdev->barmap[bar])
-			continue;
-		pci_iounmap(pdev, vdev->barmap[bar]);
-		pci_release_selected_regions(pdev, 1 << bar);
-		vdev->barmap[bar] = NULL;
-	}
+	__vfio_pci_core_unmap_bars(vdev);
 
 	list_for_each_entry_safe(dummy_res, tmp,
 				 &vdev->dummy_resources_list, res_next) {
diff --git a/drivers/vfio/pci/vfio_pci_rdwr.c b/drivers/vfio/pci/vfio_pci_rdwr.c
index 4251ee03e146..d1386a31a3a3 100644
--- a/drivers/vfio/pci/vfio_pci_rdwr.c
+++ b/drivers/vfio/pci/vfio_pci_rdwr.c
@@ -200,26 +200,13 @@ 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;
-	}
-
-	vdev->barmap[bar] = io;
+	/*
+	 * The barmap is now always set up in vfio_pci_core_enable().
+	 * Some legacy callers use this function to check if the BAR
+	 * is legitimate, so maintain that:
+	 */
 
-	return 0;
+	return vdev->barmap[bar] ? 0 : -EBUSY;
 }
 EXPORT_SYMBOL_GPL(vfio_pci_core_setup_barmap);
 
-- 
2.47.3