On Mon, Jan 08, 2024 at 10:31:07AM +0200, Hogander, Jouni wrote:
> On Thu, 2024-01-04 at 10:30 +0200, Imre Deak wrote:
> > An unexpected modeset or connector detection by a user (user space
> > or FB console) during the initialization/shutdown sequence is
> > possible either via a hotplug IRQ handling work or via the connector
> > sysfs (status/detect) interface. These modesets/detections should be
> > prevented by disabling/flushing all related hotplug handling work
> > and unregistering the interfaces that can start them at the
> > beginning of the shutdown sequence. Some of this - disabling all
> > related intel_hotplug work - will be done by the next patch, but
> > others - for instance disabling the MST hotplug works - require a
> > bigger rework.
> >
> > It makes sense - for diagnostic purpose, even with all the above
> > work and interface disabled - to detect and reject any such user
> > access. This patch does that for modeset accesses and a follow-up
> > patch for connector detection.
> >
> > After the display is disabled during the shutdown sequence, no
> > modeset should happen so it's disabled for both users and the
> > shutdown thread.
>
> Can you please explain in commit message why
> intel_display_driver_disable_user_access and
> intel_display_driver_resume_access are allowing modeset for "current"
> process?
Is it ok if I add the following instead of the last paragraph?:
"""
During driver loading/unloading/system suspend/shutdown and during
system resume after calling intel_display_driver_disable_user_access()
or intel_display_driver_resume_access() correspondigly, the current
thread is allowed to modeset (as this thread requires to do an
initial/restoring modeset or a disabling modeset), other threads (the
user threads) are not allowed to modeset.
During driver loading/system resume after calling
intel_display_driver_enable_user_access() all threads are allowed to
modeset.
During driver unloading/system suspend/shutdown after calling
intel_display_driver_suspend_access() no threads are allowed to modeset
(as the HW got disabled and should stay in this state).
"""
>
> BR,
>
> Jouni Högander
>
> >
> > Signed-off-by: Imre Deak <imre.deak@xxxxxxxxx>
> > ---
> > drivers/gpu/drm/i915/display/intel_display.c | 3 +
> > .../gpu/drm/i915/display/intel_display_core.h | 7 ++
> > .../drm/i915/display/intel_display_driver.c | 74
> > +++++++++++++++++++
> > .../drm/i915/display/intel_display_driver.h | 6 ++
> > drivers/gpu/drm/i915/i915_driver.c | 16 +++-
> > 5 files changed, 104 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/display/intel_display.c
> > b/drivers/gpu/drm/i915/display/intel_display.c
> > index 927d124457b61..31a6a82c12616 100644
> > --- a/drivers/gpu/drm/i915/display/intel_display.c
> > +++ b/drivers/gpu/drm/i915/display/intel_display.c
> > @@ -6310,6 +6310,9 @@ int intel_atomic_check(struct drm_device *dev,
> > int ret, i;
> > bool any_ms = false;
> >
> > + if (!intel_display_driver_check_access(dev_priv))
> > + return -ENODEV;
> > +
> > for_each_oldnew_intel_crtc_in_state(state, crtc,
> > old_crtc_state,
> > new_crtc_state, i) {
> > /*
> > diff --git a/drivers/gpu/drm/i915/display/intel_display_core.h
> > b/drivers/gpu/drm/i915/display/intel_display_core.h
> > index 47297ed858223..0b130ca9e6698 100644
> > --- a/drivers/gpu/drm/i915/display/intel_display_core.h
> > +++ b/drivers/gpu/drm/i915/display/intel_display_core.h
> > @@ -28,6 +28,8 @@
> > #include "intel_opregion.h"
> > #include "intel_wm_types.h"
> >
> > +struct task_struct;
> > +
> > struct drm_i915_private;
> > struct drm_property;
> > struct drm_property_blob;
> > @@ -298,6 +300,11 @@ struct intel_display {
> > const struct intel_audio_funcs *audio;
> > } funcs;
> >
> > + struct {
> > + bool any_task_allowed;
> > + struct task_struct *allowed_task;
> > + } access;
> > +
> > struct {
> > /* backlight registers and fields in struct
> > intel_panel */
> > struct mutex lock;
> > diff --git a/drivers/gpu/drm/i915/display/intel_display_driver.c
> > b/drivers/gpu/drm/i915/display/intel_display_driver.c
> > index 1974f2394a518..b2441ab9822c2 100644
> > --- a/drivers/gpu/drm/i915/display/intel_display_driver.c
> > +++ b/drivers/gpu/drm/i915/display/intel_display_driver.c
> > @@ -45,6 +45,7 @@
> > #include "intel_hdcp.h"
> > #include "intel_hotplug.h"
> > #include "intel_hti.h"
> > +#include "intel_modeset_lock.h"
> > #include "intel_modeset_setup.h"
> > #include "intel_opregion.h"
> > #include "intel_overlay.h"
> > @@ -276,6 +277,71 @@ int intel_display_driver_probe_noirq(struct
> > drm_i915_private *i915)
> > return ret;
> > }
> >
> > +static void set_display_access(struct drm_i915_private *i915,
> > + bool any_task_allowed,
> > + struct task_struct *allowed_task)
> > +{
> > + struct drm_modeset_acquire_ctx ctx;
> > + int err;
> > +
> > + intel_modeset_lock_ctx_retry(&ctx, NULL, 0, err) {
> > + err = drm_modeset_lock_all_ctx(&i915->drm, &ctx);
> > + if (err)
> > + continue;
> > +
> > + i915->display.access.any_task_allowed =
> > any_task_allowed;
> > + i915->display.access.allowed_task = allowed_task;
> > + }
> > +
> > + drm_WARN_ON(&i915->drm, err);
> > +}
> > +
> > +void intel_display_driver_enable_user_access(struct drm_i915_private
> > *i915)
> > +{
> > + set_display_access(i915, true, NULL);
> > +}
> > +
> > +void intel_display_driver_disable_user_access(struct
> > drm_i915_private *i915)
> > +{
> > + set_display_access(i915, false, current);
> > +}
> > +
> > +void intel_display_driver_suspend_access(struct drm_i915_private
> > *i915)
> > +{
> > + set_display_access(i915, false, NULL);
> > +}
> > +
> > +void intel_display_driver_resume_access(struct drm_i915_private
> > *i915)
> > +{
> > + set_display_access(i915, false, current);
> > +}
> > +
> > +bool intel_display_driver_check_access(struct drm_i915_private
> > *i915)
> > +{
> > + char comm[TASK_COMM_LEN];
> > + char current_task[TASK_COMM_LEN + 16];
> > + char allowed_task[TASK_COMM_LEN + 16] = "none";
> > +
> > + if (i915->display.access.any_task_allowed ||
> > + i915->display.access.allowed_task == current)
> > + return true;
> > +
> > + snprintf(current_task, sizeof(current_task), "%s[%d]",
> > + get_task_comm(comm, current),
> > + task_pid_vnr(current));
> > +
> > + if (i915->display.access.allowed_task)
> > + snprintf(allowed_task, sizeof(allowed_task),
> > "%s[%d]",
> > + get_task_comm(comm, i915-
> > >display.access.allowed_task),
> > + task_pid_vnr(i915-
> > >display.access.allowed_task));
> > +
> > + drm_dbg_kms(&i915->drm,
> > + "Reject display access from task %s (allowed to
> > %s)\n",
> > + current_task, allowed_task);
> > +
> > + return false;
> > +}
> > +
> > /* part #2: call after irq install, but before gem init */
> > int intel_display_driver_probe_nogem(struct drm_i915_private *i915)
> > {
> > @@ -326,6 +392,8 @@ int intel_display_driver_probe_nogem(struct
> > drm_i915_private *i915)
> > intel_vga_disable(i915);
> > intel_setup_outputs(i915);
> >
> > + intel_display_driver_disable_user_access(i915);
> > +
> > drm_modeset_lock_all(dev);
> > intel_modeset_setup_hw_state(i915, dev-
> > >mode_config.acquire_ctx);
> > intel_acpi_assign_connector_fwnodes(i915);
> > @@ -393,6 +461,8 @@ void intel_display_driver_register(struct
> > drm_i915_private *i915)
> >
> > intel_audio_init(i915);
> >
> > + intel_display_driver_enable_user_access(i915);
> > +
> > intel_display_debugfs_register(i915);
> >
> > /*
> > @@ -440,6 +510,8 @@ void intel_display_driver_remove_noirq(struct
> > drm_i915_private *i915)
> > if (!HAS_DISPLAY(i915))
> > return;
> >
> > + intel_display_driver_suspend_access(i915);
> > +
> > /*
> > * Due to the hpd irq storm handling the hotplug work can re-
> > arm the
> > * poll handlers. Hence disable polling after hpd handling is
> > shut down.
> > @@ -493,6 +565,8 @@ void intel_display_driver_unregister(struct
> > drm_i915_private *i915)
> > */
> > drm_kms_helper_poll_fini(&i915->drm);
> >
> > + intel_display_driver_disable_user_access(i915);
> > +
> > intel_audio_deinit(i915);
> >
> > drm_atomic_helper_shutdown(&i915->drm);
> > diff --git a/drivers/gpu/drm/i915/display/intel_display_driver.h
> > b/drivers/gpu/drm/i915/display/intel_display_driver.h
> > index c276a58ee3293..42cc4af6d3fd5 100644
> > --- a/drivers/gpu/drm/i915/display/intel_display_driver.h
> > +++ b/drivers/gpu/drm/i915/display/intel_display_driver.h
> > @@ -32,5 +32,11 @@ int __intel_display_driver_resume(struct
> > drm_i915_private *i915,
> > struct drm_atomic_state *state,
> > struct drm_modeset_acquire_ctx
> > *ctx);
> >
> > +void intel_display_driver_enable_user_access(struct drm_i915_private
> > *i915);
> > +void intel_display_driver_disable_user_access(struct
> > drm_i915_private *i915);
> > +void intel_display_driver_suspend_access(struct drm_i915_private
> > *i915);
> > +void intel_display_driver_resume_access(struct drm_i915_private
> > *i915);
> > +bool intel_display_driver_check_access(struct drm_i915_private
> > *i915);
> > +
> > #endif /* __INTEL_DISPLAY_DRIVER_H__ */
> >
> > diff --git a/drivers/gpu/drm/i915/i915_driver.c
> > b/drivers/gpu/drm/i915/i915_driver.c
> > index 166476948c896..068ca48e05323 100644
> > --- a/drivers/gpu/drm/i915/i915_driver.c
> > +++ b/drivers/gpu/drm/i915/i915_driver.c
> > @@ -1006,6 +1006,7 @@ void i915_driver_shutdown(struct
> > drm_i915_private *i915)
> > intel_fbdev_set_suspend(&i915->drm, FBINFO_STATE_SUSPENDED,
> > true);
> > if (HAS_DISPLAY(i915)) {
> > drm_kms_helper_poll_disable(&i915->drm);
> > + intel_display_driver_disable_user_access(i915);
> >
> > drm_atomic_helper_shutdown(&i915->drm);
> > }
> > @@ -1015,6 +1016,8 @@ void i915_driver_shutdown(struct
> > drm_i915_private *i915)
> > intel_runtime_pm_disable_interrupts(i915);
> > intel_hpd_cancel_work(i915);
> >
> > + intel_display_driver_suspend_access(i915);
> > +
> > intel_suspend_encoders(i915);
> > intel_shutdown_encoders(i915);
> >
> > @@ -1082,8 +1085,10 @@ static int i915_drm_suspend(struct drm_device
> > *dev)
> > * properly. */
> > intel_power_domains_disable(dev_priv);
> > intel_fbdev_set_suspend(dev, FBINFO_STATE_SUSPENDED, true);
> > - if (HAS_DISPLAY(dev_priv))
> > + if (HAS_DISPLAY(dev_priv)) {
> > drm_kms_helper_poll_disable(dev);
> > + intel_display_driver_disable_user_access(dev_priv);
> > + }
> >
> > pci_save_state(pdev);
> >
> > @@ -1094,6 +1099,8 @@ static int i915_drm_suspend(struct drm_device
> > *dev)
> > intel_runtime_pm_disable_interrupts(dev_priv);
> > intel_hpd_cancel_work(dev_priv);
> >
> > + intel_display_driver_suspend_access(dev_priv);
> > +
> > intel_suspend_encoders(dev_priv);
> >
> > /* Must be called before GGTT is suspended. */
> > @@ -1243,14 +1250,19 @@ static int i915_drm_resume(struct drm_device
> > *dev)
> > intel_display_driver_init_hw(dev_priv);
> >
> > intel_clock_gating_init(dev_priv);
> > +
> > + intel_display_driver_resume_access(dev_priv);
> > +
> > intel_hpd_init(dev_priv);
> >
> > /* MST sideband requires HPD interrupts enabled */
> > intel_dp_mst_resume(dev_priv);
> > intel_display_driver_resume(dev_priv);
> >
> > - if (HAS_DISPLAY(dev_priv))
> > + if (HAS_DISPLAY(dev_priv)) {
> > + intel_display_driver_enable_user_access(dev_priv);
> > drm_kms_helper_poll_enable(dev);
> > + }
> > intel_hpd_poll_disable(dev_priv);
> >
> > intel_opregion_resume(dev_priv);
>
