On Mon, 2024-01-08 at 11:20 +0200, Imre Deak wrote:
> 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?:
Yes. That helps to understand the patch. You could consider to add some
comments into code as well. For me the commit message change is enough.
BR,
Jouni Högander
>
> """
> 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);
> >
