On Tue, Oct 07, 2025 at 08:25:14PM +0000, Jia Yao wrote:
> Make i915's PCI device management more robust by always setting/clearing
> the memory access bit when enabling/disabling the device, and by
> consolidating this logic into helper functions.
>
> It fixes kexec reboot issue by disabling memory access before shutting
> down the device, which can block unsafe and unwanted access from DMA.
>
> v2:
> - follow brace style
>
> Link: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/14598
> Cc: Alex Zuo <[email protected]>
> Cc: Shuicheng Lin <[email protected]>
> Cc: Askar Safin <[email protected]>
> Cc: Pingfan Liu <[email protected]>
> Suggested-by: Chris Wilson <[email protected]>
> Signed-off-by: Jia Yao <[email protected]>
> ---
> drivers/gpu/drm/i915/i915_driver.c | 35 +++++++++++++++++++++++++++---
> 1 file changed, 32 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_driver.c
> b/drivers/gpu/drm/i915/i915_driver.c
> index b46cb54ef5dc..766f85726b67 100644
> --- a/drivers/gpu/drm/i915/i915_driver.c
> +++ b/drivers/gpu/drm/i915/i915_driver.c
> @@ -118,6 +118,33 @@
>
> static const struct drm_driver i915_drm_driver;
>
> +static int i915_enable_device(struct pci_dev *pdev)
> +{
> + u32 cmd;
> + int ret;
> +
> + ret = pci_enable_device(pdev);
> + if (ret)
> + return ret;
> +
> + pci_read_config_dword(pdev, PCI_COMMAND, &cmd);
> + if (!(cmd & PCI_COMMAND_MEMORY))
> + pci_write_config_dword(pdev, PCI_COMMAND, cmd |
> PCI_COMMAND_MEMORY);
> +
> + return 0;
> +}
NAK. If the pci code is broken then fix the problem there.
Do not add ugly hacks into random drivers.
> +
> +static void i915_disable_device(struct pci_dev *pdev)
> +{
> + u32 cmd;
> +
> + pci_read_config_dword(pdev, PCI_COMMAND, &cmd);
> + if (cmd & PCI_COMMAND_MEMORY)
> + pci_write_config_dword(pdev, PCI_COMMAND, cmd &
> ~PCI_COMMAND_MEMORY);
> +
> + pci_disable_device(pdev);
> +}
> +
> static int i915_workqueues_init(struct drm_i915_private *dev_priv)
> {
> /*
> @@ -788,7 +815,7 @@ int i915_driver_probe(struct pci_dev *pdev, const struct
> pci_device_id *ent)
> struct intel_display *display;
> int ret;
>
> - ret = pci_enable_device(pdev);
> + ret = i915_enable_device(pdev);
> if (ret) {
> pr_err("Failed to enable graphics device: %pe\n", ERR_PTR(ret));
> return ret;
> @@ -796,7 +823,7 @@ int i915_driver_probe(struct pci_dev *pdev, const struct
> pci_device_id *ent)
>
> i915 = i915_driver_create(pdev, ent);
> if (IS_ERR(i915)) {
> - pci_disable_device(pdev);
> + i915_disable_device(pdev);
> return PTR_ERR(i915);
> }
>
> @@ -885,7 +912,7 @@ int i915_driver_probe(struct pci_dev *pdev, const struct
> pci_device_id *ent)
> enable_rpm_wakeref_asserts(&i915->runtime_pm);
> i915_driver_late_release(i915);
> out_pci_disable:
> - pci_disable_device(pdev);
> + i915_disable_device(pdev);
> i915_probe_error(i915, "Device initialization failed (%d)\n", ret);
> return ret;
> }
> @@ -1003,6 +1030,7 @@ void i915_driver_shutdown(struct drm_i915_private *i915)
>
> intel_dmc_suspend(display);
>
> + intel_pxp_fini(i915);
What is that doing in this patch?
> i915_gem_suspend(i915);
>
> /*
> @@ -1020,6 +1048,7 @@ void i915_driver_shutdown(struct drm_i915_private *i915)
> enable_rpm_wakeref_asserts(&i915->runtime_pm);
>
> intel_runtime_pm_driver_last_release(&i915->runtime_pm);
> + i915_disable_device(to_pci_dev(i915->drm.dev));
> }
>
> static bool suspend_to_idle(struct drm_i915_private *dev_priv)
> --
> 2.34.1
--
Ville Syrjälä
Intel
