[PATCH 2/2] vfio/pci: Latch all module parameters per device

[Alex Williamson <alex.williamson@nvidia.com>]

The vfio-pci module parameters of disable_idle_d3, nointxmask, and
disable_vga latch vfio-pci policy into vfio-pci-core globals each time
the vfio-pci module is initialized.  The disable_idle_d3 parameter has
already migrated to a per-device flag in order to provide consistency
for refcounted PM operations for the lifetime of the device
registration.

Pull the remaining vfio-pci module-parameter policy out of vfio-pci-core
into per-device flags set at device initialization.

This also restores the mutable aspect of the disable_idle_d3 and
nointxmask module parameters for vfio-pci, with the caveat that the
parameters are latched into the device at probe.

A notable change for variant drivers is that their devices are no longer
affected by vfio-pci module parameters and those drivers may need to
adopt similar module parameters if any devices have a hidden dependency
on vfio-pci setting non-default policy.

Assisted-by: Claude:claude-opus-4-8
Signed-off-by: Alex Williamson <alex.williamson@nvidia.com>
---
 drivers/vfio/pci/vfio_pci.c      | 30 ++++++++++++++++++++++--------
 drivers/vfio/pci/vfio_pci_core.c | 26 ++++++--------------------
 include/linux/vfio_pci_core.h    |  4 ++--
 3 files changed, 30 insertions(+), 30 deletions(-)

diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
index 0c771064c0b8..830369ff878d 100644
--- a/drivers/vfio/pci/vfio_pci.c
+++ b/drivers/vfio/pci/vfio_pci.c
@@ -125,9 +125,30 @@ static int vfio_pci_open_device(struct vfio_device *core_vdev)
 	return 0;
 }
 
+static int vfio_pci_init_dev(struct vfio_device *core_vdev)
+{
+	struct vfio_pci_core_device *vdev =
+		container_of(core_vdev, struct vfio_pci_core_device, vdev);
+
+	/*
+	 * These behaviors originated in vfio-pci and moved into
+	 * vfio-pci-core when the driver was split; vfio-pci remains the
+	 * only driver that toggles them.  Latch our module parameters per
+	 * device at init time so that later parameter changes do not
+	 * affect already-initialized devices.
+	 */
+	vdev->nointxmask = nointxmask;
+	vdev->disable_idle_d3 = disable_idle_d3;
+#ifdef CONFIG_VFIO_PCI_VGA
+	vdev->disable_vga = disable_vga;
+#endif
+
+	return vfio_pci_core_init_dev(core_vdev);
+}
+
 static const struct vfio_device_ops vfio_pci_ops = {
 	.name		= "vfio-pci",
-	.init		= vfio_pci_core_init_dev,
+	.init		= vfio_pci_init_dev,
 	.release	= vfio_pci_core_release_dev,
 	.open_device	= vfio_pci_open_device,
 	.close_device	= vfio_pci_core_close_device,
@@ -256,13 +277,6 @@ static void __init vfio_pci_fill_ids(void)
 static int __init vfio_pci_init(void)
 {
 	int ret;
-	bool is_disable_vga = true;
-
-#ifdef CONFIG_VFIO_PCI_VGA
-	is_disable_vga = disable_vga;
-#endif
-
-	vfio_pci_core_set_params(nointxmask, is_disable_vga, disable_idle_d3);
 
 	/* Register and scan for devices */
 	ret = pci_register_driver(&vfio_pci_driver);
diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_core.c
index 9f71eae0cc94..61cf1a1996b0 100644
--- a/drivers/vfio/pci/vfio_pci_core.c
+++ b/drivers/vfio/pci/vfio_pci_core.c
@@ -38,10 +38,6 @@
 #define DRIVER_AUTHOR   "Alex Williamson <alex.williamson@redhat.com>"
 #define DRIVER_DESC "core driver for VFIO based PCI devices"
 
-static bool nointxmask;
-static bool disable_vga;
-static bool disable_idle_d3;
-
 static void vfio_pci_eventfd_rcu_free(struct rcu_head *rcu)
 {
 	struct vfio_pci_eventfd *eventfd =
@@ -92,10 +88,10 @@ struct vfio_pci_vf_token {
 	int			users;
 };
 
-static inline bool vfio_vga_disabled(void)
+static inline bool vfio_vga_disabled(struct vfio_pci_core_device *vdev)
 {
 #ifdef CONFIG_VFIO_PCI_VGA
-	return disable_vga;
+	return vdev->disable_vga;
 #else
 	return true;
 #endif
@@ -111,11 +107,12 @@ static inline bool vfio_vga_disabled(void)
  */
 static unsigned int vfio_pci_set_decode(struct pci_dev *pdev, bool single_vga)
 {
+	struct vfio_pci_core_device *vdev = dev_get_drvdata(&pdev->dev);
 	struct pci_dev *tmp = NULL;
 	unsigned char max_busnr;
 	unsigned int decodes;
 
-	if (single_vga || !vfio_vga_disabled() || pci_is_root_bus(pdev->bus))
+	if (single_vga || !vfio_vga_disabled(vdev) || pci_is_root_bus(pdev->bus))
 		return VGA_RSRC_NORMAL_IO | VGA_RSRC_NORMAL_MEM |
 		       VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM;
 
@@ -562,7 +559,7 @@ int vfio_pci_core_enable(struct vfio_pci_core_device *vdev)
 	if (!vdev->pci_saved_state)
 		pci_dbg(pdev, "%s: Couldn't store saved state\n", __func__);
 
-	if (likely(!nointxmask)) {
+	if (likely(!vdev->nointxmask)) {
 		if (vfio_pci_nointx(pdev)) {
 			pci_info(pdev, "Masking broken INTx support\n");
 			vdev->nointx = true;
@@ -602,7 +599,7 @@ int vfio_pci_core_enable(struct vfio_pci_core_device *vdev)
 		vdev->has_dyn_msix = false;
 	}
 
-	if (!vfio_vga_disabled() && vfio_pci_is_vga(pdev))
+	if (!vfio_vga_disabled(vdev) && vfio_pci_is_vga(pdev))
 		vdev->has_vga = true;
 
 	vfio_pci_core_map_bars(vdev);
@@ -2144,8 +2141,6 @@ int vfio_pci_core_init_dev(struct vfio_device *core_vdev)
 	init_rwsem(&vdev->memory_lock);
 	xa_init(&vdev->ctx);
 
-	vdev->disable_idle_d3 = disable_idle_d3;
-
 	return 0;
 }
 EXPORT_SYMBOL_GPL(vfio_pci_core_init_dev);
@@ -2624,15 +2619,6 @@ static void vfio_pci_dev_set_try_reset(struct vfio_device_set *dev_set)
 	}
 }
 
-void vfio_pci_core_set_params(bool is_nointxmask, bool is_disable_vga,
-			      bool is_disable_idle_d3)
-{
-	nointxmask = is_nointxmask;
-	disable_vga = is_disable_vga;
-	disable_idle_d3 = is_disable_idle_d3;
-}
-EXPORT_SYMBOL_GPL(vfio_pci_core_set_params);
-
 static void vfio_pci_core_cleanup(void)
 {
 	vfio_pci_uninit_perm_bits();
diff --git a/include/linux/vfio_pci_core.h b/include/linux/vfio_pci_core.h
index 27aab3fdbb91..74b950d73aef 100644
--- a/include/linux/vfio_pci_core.h
+++ b/include/linux/vfio_pci_core.h
@@ -128,6 +128,8 @@ struct vfio_pci_core_device {
 	bool			pm_intx_masked:1;
 	bool			pm_runtime_engaged:1;
 	bool			disable_idle_d3:1;
+	bool			nointxmask:1;
+	bool			disable_vga:1;
 	bool			sriov_active;
 	struct pci_saved_state	*pci_saved_state;
 	struct pci_saved_state	*pm_save;
@@ -158,8 +160,6 @@ int vfio_pci_core_register_dev_region(struct vfio_pci_core_device *vdev,
 				      unsigned int type, unsigned int subtype,
 				      const struct vfio_pci_regops *ops,
 				      size_t size, u32 flags, void *data);
-void vfio_pci_core_set_params(bool nointxmask, bool is_disable_vga,
-			      bool is_disable_idle_d3);
 void vfio_pci_core_close_device(struct vfio_device *core_vdev);
 int vfio_pci_core_init_dev(struct vfio_device *core_vdev);
 void vfio_pci_core_release_dev(struct vfio_device *core_vdev);
-- 
2.53.0