Re: [Intel-gfx] [PATCH v4 10/17] drm/i915/pxp: Implement PXP irq handler

[Rodrigo Vivi <rodrigo.vivi@intel.com>]

On Mon, May 24, 2021 at 10:47:56PM -0700, Daniele Ceraolo Spurio wrote:
> From: "Huang, Sean Z" <sean.z.huang@intel.com>
> 
> The HW will generate a teardown interrupt when session termination is
> required, which requires i915 to submit a terminating batch. Once the HW
> is done with the termination it will generate another interrupt, at
> which point it is safe to re-create the session.
> 
> Since the termination and re-creation flow is something we want to
> trigger from the driver as well, use a common work function that can be
> called both from the irq handler and from the driver set-up flows, which
> has the addded benefit of allowing us to skip any extra locks because
> the work itself serializes the operations.
> 
> v2: use struct completion instead of bool (Chris)
> v3: drop locks, clean up functions and improve comments (Chris),
>     move to common work function.
> v4: improve comments, simplify wait logic (Rodrigo)
> 
> Signed-off-by: Huang, Sean Z <sean.z.huang@intel.com>
> Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
> Cc: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
> ---
>  drivers/gpu/drm/i915/Makefile                |  1 +
>  drivers/gpu/drm/i915/gt/intel_gt_irq.c       |  7 ++
>  drivers/gpu/drm/i915/i915_reg.h              |  1 +
>  drivers/gpu/drm/i915/pxp/intel_pxp.c         | 66 +++++++++++--
>  drivers/gpu/drm/i915/pxp/intel_pxp.h         |  8 ++
>  drivers/gpu/drm/i915/pxp/intel_pxp_irq.c     | 97 ++++++++++++++++++++
>  drivers/gpu/drm/i915/pxp/intel_pxp_irq.h     | 32 +++++++
>  drivers/gpu/drm/i915/pxp/intel_pxp_session.c | 54 ++++++++++-
>  drivers/gpu/drm/i915/pxp/intel_pxp_session.h |  5 +-
>  drivers/gpu/drm/i915/pxp/intel_pxp_tee.c     |  8 +-
>  drivers/gpu/drm/i915/pxp/intel_pxp_types.h   | 18 ++++
>  11 files changed, 281 insertions(+), 16 deletions(-)
>  create mode 100644 drivers/gpu/drm/i915/pxp/intel_pxp_irq.c
>  create mode 100644 drivers/gpu/drm/i915/pxp/intel_pxp_irq.h
> 
> diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
> index 0fba97014512..29331bbb3e98 100644
> --- a/drivers/gpu/drm/i915/Makefile
> +++ b/drivers/gpu/drm/i915/Makefile
> @@ -277,6 +277,7 @@ i915-y += i915_perf.o
>  i915-$(CONFIG_DRM_I915_PXP) += \
>  	pxp/intel_pxp.o \
>  	pxp/intel_pxp_cmd.o \
> +	pxp/intel_pxp_irq.o \
>  	pxp/intel_pxp_session.o \
>  	pxp/intel_pxp_tee.o
>  
> diff --git a/drivers/gpu/drm/i915/gt/intel_gt_irq.c b/drivers/gpu/drm/i915/gt/intel_gt_irq.c
> index 9fc6c912a4e5..7c4ec8880b1a 100644
> --- a/drivers/gpu/drm/i915/gt/intel_gt_irq.c
> +++ b/drivers/gpu/drm/i915/gt/intel_gt_irq.c
> @@ -13,6 +13,7 @@
>  #include "intel_lrc_reg.h"
>  #include "intel_uncore.h"
>  #include "intel_rps.h"
> +#include "pxp/intel_pxp_irq.h"
>  
>  static void guc_irq_handler(struct intel_guc *guc, u16 iir)
>  {
> @@ -106,6 +107,9 @@ gen11_other_irq_handler(struct intel_gt *gt, const u8 instance,
>  	if (instance == OTHER_GTPM_INSTANCE)
>  		return gen11_rps_irq_handler(&gt->rps, iir);
>  
> +	if (instance == OTHER_KCR_INSTANCE)
> +		return intel_pxp_irq_handler(&gt->pxp, iir);
> +
>  	WARN_ONCE(1, "unhandled other interrupt instance=0x%x, iir=0x%x\n",
>  		  instance, iir);
>  }
> @@ -232,6 +236,9 @@ void gen11_gt_irq_reset(struct intel_gt *gt)
>  	intel_uncore_write(uncore, GEN11_GPM_WGBOXPERF_INTR_MASK,  ~0);
>  	intel_uncore_write(uncore, GEN11_GUC_SG_INTR_ENABLE, 0);
>  	intel_uncore_write(uncore, GEN11_GUC_SG_INTR_MASK,  ~0);
> +
> +	intel_uncore_write(uncore, GEN11_CRYPTO_RSVD_INTR_ENABLE, 0);
> +	intel_uncore_write(uncore, GEN11_CRYPTO_RSVD_INTR_MASK,  ~0);
>  }
>  
>  void gen11_gt_irq_postinstall(struct intel_gt *gt)
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index 4dbe79009c0e..297671d78076 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -8023,6 +8023,7 @@ enum {
>  /* irq instances for OTHER_CLASS */
>  #define OTHER_GUC_INSTANCE	0
>  #define OTHER_GTPM_INSTANCE	1
> +#define OTHER_KCR_INSTANCE	4
>  
>  #define GEN11_INTR_IDENTITY_REG(x)	_MMIO(0x190060 + ((x) * 4))
>  
> diff --git a/drivers/gpu/drm/i915/pxp/intel_pxp.c b/drivers/gpu/drm/i915/pxp/intel_pxp.c
> index e48debb5ca22..6b0e7170c29b 100644
> --- a/drivers/gpu/drm/i915/pxp/intel_pxp.c
> +++ b/drivers/gpu/drm/i915/pxp/intel_pxp.c
> @@ -2,7 +2,9 @@
>  /*
>   * Copyright(c) 2020 Intel Corporation.
>   */
> +#include <linux/workqueue.h>
>  #include "intel_pxp.h"
> +#include "intel_pxp_irq.h"
>  #include "intel_pxp_session.h"
>  #include "intel_pxp_tee.h"
>  #include "gt/intel_context.h"
> @@ -66,6 +68,16 @@ void intel_pxp_init(struct intel_pxp *pxp)
>  	if (!HAS_PXP(gt->i915))
>  		return;
>  
> +	/*
> +	 * we'll use the completion to check if there is a termination pending,
> +	 * so we start it as completed and we reinit it when a termination
> +	 * is triggered.
> +	 */
> +	init_completion(&pxp->termination);
> +	complete_all(&pxp->termination);
> +
> +	INIT_WORK(&pxp->session_work, intel_pxp_session_work);
> +
>  	ret = create_vcs_context(pxp);
>  	if (ret)
>  		return;
> @@ -94,19 +106,61 @@ void intel_pxp_fini(struct intel_pxp *pxp)
>  	destroy_vcs_context(pxp);
>  }
>  
> -void intel_pxp_init_hw(struct intel_pxp *pxp)
> +void intel_pxp_mark_termination_in_progress(struct intel_pxp *pxp)
>  {
> -	int ret;
> +	pxp->arb_is_valid = false;
> +	reinit_completion(&pxp->termination);
> +}
> +
> +static void intel_pxp_queue_termination(struct intel_pxp *pxp)
> +{
> +	struct intel_gt *gt = pxp_to_gt(pxp);
> +
> +	/*
> +	 * We want to get the same effect as if we received a termination
> +	 * interrupt, so just pretend that we did.
> +	 */
> +	spin_lock_irq(&gt->irq_lock);
> +	intel_pxp_mark_termination_in_progress(pxp);
> +	pxp->session_events |= PXP_TERMINATION_REQUEST;
> +	queue_work(system_unbound_wq, &pxp->session_work);
> +	spin_unlock_irq(&gt->irq_lock);
> +}
>  
> +/*
> + * the arb session is restarted from the irq work when we receive the
> + * termination completion interrupt
> + */
> +int intel_pxp_wait_for_arb_start(struct intel_pxp *pxp)
> +{
> +	if (!intel_pxp_is_enabled(pxp))
> +		return 0;
> +
> +	if (!wait_for_completion_timeout(&pxp->termination,
> +					 msecs_to_jiffies(100)))
> +		return -ETIMEDOUT;
> +
> +	if (!pxp->arb_is_valid)
> +		return -EIO;
> +
> +	return 0;
> +}
> +
> +void intel_pxp_init_hw(struct intel_pxp *pxp)
> +{
>  	kcr_pxp_enable(pxp_to_gt(pxp));
> +	intel_pxp_irq_enable(pxp);
>  
> -	/* always emit a full termination to clean the state */
> -	ret = intel_pxp_terminate_arb_session_and_global(pxp);
> -	if (!ret)
> -		intel_pxp_create_arb_session(pxp);
> +	/*
> +	 * the session could've been attacked while we weren't loaded, so
> +	 * handle it as if it was and re-create it.
> +	 */
> +	intel_pxp_queue_termination(pxp);
>  }
>  
>  void intel_pxp_fini_hw(struct intel_pxp *pxp)
>  {
>  	kcr_pxp_disable(pxp_to_gt(pxp));
> +
> +	intel_pxp_irq_disable(pxp);
>  }
> diff --git a/drivers/gpu/drm/i915/pxp/intel_pxp.h b/drivers/gpu/drm/i915/pxp/intel_pxp.h
> index 8eeb65af78b1..074b3b980957 100644
> --- a/drivers/gpu/drm/i915/pxp/intel_pxp.h
> +++ b/drivers/gpu/drm/i915/pxp/intel_pxp.h
> @@ -30,6 +30,9 @@ void intel_pxp_fini(struct intel_pxp *pxp);
>  
>  void intel_pxp_init_hw(struct intel_pxp *pxp);
>  void intel_pxp_fini_hw(struct intel_pxp *pxp);
> +
> +void intel_pxp_mark_termination_in_progress(struct intel_pxp *pxp);
> +int intel_pxp_wait_for_arb_start(struct intel_pxp *pxp);
>  #else
>  static inline void intel_pxp_init(struct intel_pxp *pxp)
>  {
> @@ -38,6 +41,11 @@ static inline void intel_pxp_init(struct intel_pxp *pxp)
>  static inline void intel_pxp_fini(struct intel_pxp *pxp)
>  {
>  }
> +
> +static inline int intel_pxp_wait_for_arb_start(struct intel_pxp *pxp)
> +{
> +	return 0;
> +}
>  #endif
>  
>  #endif /* __INTEL_PXP_H__ */
> diff --git a/drivers/gpu/drm/i915/pxp/intel_pxp_irq.c b/drivers/gpu/drm/i915/pxp/intel_pxp_irq.c
> new file mode 100644
> index 000000000000..196449243515
> --- /dev/null
> +++ b/drivers/gpu/drm/i915/pxp/intel_pxp_irq.c
> @@ -0,0 +1,97 @@
> +// SPDX-License-Identifier: MIT
> +/*
> + * Copyright(c) 2020 Intel Corporation.
> + */
> +#include <linux/workqueue.h>
> +#include "intel_pxp.h"
> +#include "intel_pxp_irq.h"
> +#include "intel_pxp_session.h"
> +#include "gt/intel_gt_irq.h"
> +#include "i915_irq.h"
> +#include "i915_reg.h"
> +
> +/**
> + * intel_pxp_irq_handler - Handles PXP interrupts.
> + * @pxp: pointer to pxp struct
> + * @iir: interrupt vector
> + */
> +void intel_pxp_irq_handler(struct intel_pxp *pxp, u16 iir)
> +{
> +	struct intel_gt *gt = pxp_to_gt(pxp);
> +
> +	if (GEM_WARN_ON(!intel_pxp_is_enabled(pxp)))
> +		return;
> +
> +	lockdep_assert_held(&gt->irq_lock);
> +
> +	if (unlikely(!iir))
> +		return;
> +
> +	if (iir & (GEN12_DISPLAY_PXP_STATE_TERMINATED_INTERRUPT |
> +		   GEN12_DISPLAY_APP_TERMINATED_PER_FW_REQ_INTERRUPT)) {
> +		/* immediately mark PXP as inactive on termination */
> +		intel_pxp_mark_termination_in_progress(pxp);
> +		pxp->session_events |= PXP_TERMINATION_REQUEST;
> +	}
> +
> +	if (iir & GEN12_DISPLAY_STATE_RESET_COMPLETE_INTERRUPT)
> +		pxp->session_events |= PXP_TERMINATION_COMPLETE;
> +
> +	if (pxp->session_events)
> +		queue_work(system_unbound_wq, &pxp->session_work);
> +}
> +
> +static inline void __pxp_set_interrupts(struct intel_gt *gt, u32 interrupts)
> +{
> +	struct intel_uncore *uncore = gt->uncore;
> +	const u32 mask = interrupts << 16;
> +
> +	intel_uncore_write(uncore, GEN11_CRYPTO_RSVD_INTR_ENABLE, mask);
> +	intel_uncore_write(uncore, GEN11_CRYPTO_RSVD_INTR_MASK,  ~mask);
> +}
> +
> +static inline void pxp_irq_reset(struct intel_gt *gt)
> +{
> +	spin_lock_irq(&gt->irq_lock);
> +	gen11_gt_reset_one_iir(gt, 0, GEN11_KCR);
> +	spin_unlock_irq(&gt->irq_lock);
> +}
> +
> +void intel_pxp_irq_enable(struct intel_pxp *pxp)
> +{
> +	struct intel_gt *gt = pxp_to_gt(pxp);
> +
> +	spin_lock_irq(&gt->irq_lock);
> +	if (!pxp->irq_enabled) {
> +		WARN_ON_ONCE(gen11_gt_reset_one_iir(gt, 0, GEN11_KCR));
> +		__pxp_set_interrupts(gt, GEN12_PXP_INTERRUPTS);
> +		pxp->irq_enabled = true;
> +	}
> +	spin_unlock_irq(&gt->irq_lock);
> +}
> +
> +void intel_pxp_irq_disable(struct intel_pxp *pxp)
> +{
> +	struct intel_gt *gt = pxp_to_gt(pxp);
> +
> +	/*
> +	 * We always need to submit a global termination when we re-enable the
> +	 * interrupts, so there is no need to make sure that the session state
> +	 * makes sense at the end of this function. Just make sure this is not
> +	 * called in a path were the driver consider the session as valid and
> +	 * doesn't call a termination on restart.
> +	 */
> +	GEM_WARN_ON(intel_pxp_is_active(pxp));
> +
> +	spin_lock_irq(&gt->irq_lock);
> +
> +	pxp->irq_enabled = false;
> +	__pxp_set_interrupts(gt, 0);
> +
> +	spin_unlock_irq(&gt->irq_lock);
> +	intel_synchronize_irq(gt->i915);
> +
> +	pxp_irq_reset(gt);
> +
> +	flush_work(&pxp->session_work);
> +}
> diff --git a/drivers/gpu/drm/i915/pxp/intel_pxp_irq.h b/drivers/gpu/drm/i915/pxp/intel_pxp_irq.h
> new file mode 100644
> index 000000000000..8b5793654844
> --- /dev/null
> +++ b/drivers/gpu/drm/i915/pxp/intel_pxp_irq.h
> @@ -0,0 +1,32 @@
> +/* SPDX-License-Identifier: MIT */

oh, forgot this:

// SPDX-License-Identifier: MIT

> +/*
> + * Copyright(c) 2020, Intel Corporation. All rights reserved.
> + */
> +
> +#ifndef __INTEL_PXP_IRQ_H__
> +#define __INTEL_PXP_IRQ_H__
> +
> +#include <linux/types.h>
> +
> +struct intel_pxp;
> +
> +#define GEN12_DISPLAY_PXP_STATE_TERMINATED_INTERRUPT BIT(1)
> +#define GEN12_DISPLAY_APP_TERMINATED_PER_FW_REQ_INTERRUPT BIT(2)
> +#define GEN12_DISPLAY_STATE_RESET_COMPLETE_INTERRUPT BIT(3)
> +
> +#define GEN12_PXP_INTERRUPTS \
> +	(GEN12_DISPLAY_PXP_STATE_TERMINATED_INTERRUPT | \
> +	 GEN12_DISPLAY_APP_TERMINATED_PER_FW_REQ_INTERRUPT | \
> +	 GEN12_DISPLAY_STATE_RESET_COMPLETE_INTERRUPT)
> +
> +#ifdef CONFIG_DRM_I915_PXP
> +void intel_pxp_irq_enable(struct intel_pxp *pxp);
> +void intel_pxp_irq_disable(struct intel_pxp *pxp);
> +void intel_pxp_irq_handler(struct intel_pxp *pxp, u16 iir);
> +#else
> +static inline void intel_pxp_irq_handler(struct intel_pxp *pxp, u16 iir)
> +{
> +}
> +#endif
> +
> +#endif /* __INTEL_PXP_IRQ_H__ */
> diff --git a/drivers/gpu/drm/i915/pxp/intel_pxp_session.c b/drivers/gpu/drm/i915/pxp/intel_pxp_session.c
> index b8e24adeb1f3..e751122cb24a 100644
> --- a/drivers/gpu/drm/i915/pxp/intel_pxp_session.c
> +++ b/drivers/gpu/drm/i915/pxp/intel_pxp_session.c
> @@ -48,7 +48,7 @@ static int pxp_wait_for_session_state(struct intel_pxp *pxp, u32 id, bool in_pla
>  	return ret;
>  }
>  
> -int intel_pxp_create_arb_session(struct intel_pxp *pxp)
> +static int pxp_create_arb_session(struct intel_pxp *pxp)
>  {
>  	struct intel_gt *gt = pxp_to_gt(pxp);
>  	int ret;
> @@ -77,12 +77,13 @@ int intel_pxp_create_arb_session(struct intel_pxp *pxp)
>  	return 0;
>  }
>  
> -int intel_pxp_terminate_arb_session_and_global(struct intel_pxp *pxp)
> +static int pxp_terminate_arb_session_and_global(struct intel_pxp *pxp)
>  {
>  	int ret;
>  	struct intel_gt *gt = pxp_to_gt(pxp);
>  
> -	pxp->arb_is_valid = false;
> +	/* must mark termination in progress calling this function */
> +	GEM_WARN_ON(pxp->arb_is_valid);
>  
>  	/* terminate the hw sessions */
>  	ret = intel_pxp_terminate_session(pxp, ARB_SESSION);
> @@ -101,3 +102,50 @@ int intel_pxp_terminate_arb_session_and_global(struct intel_pxp *pxp)
>  
>  	return ret;
>  }
> +
> +static void pxp_terminate(struct intel_pxp *pxp)
> +{
> +	int ret;
> +
> +	pxp->global_state_attacked = true;
> +
> +	/*
> +	 * if we fail to submit the termination there is no point in waiting for
> +	 * it to complete. PXP will be marked as non-active until the next
> +	 * termination is issued.
> +	 */
> +	ret = pxp_terminate_arb_session_and_global(pxp);
> +	if (ret)
> +		complete_all(&pxp->termination);
> +}
> +
> +static void pxp_terminate_complete(struct intel_pxp *pxp)
> +{
> +	/* Re-create the arb session after teardown handle complete */
> +	if (fetch_and_zero(&pxp->global_state_attacked))
> +		pxp_create_arb_session(pxp);
> +
> +	complete_all(&pxp->termination);
> +}
> +
> +void intel_pxp_session_work(struct work_struct *work)
> +{
> +	struct intel_pxp *pxp = container_of(work, typeof(*pxp), session_work);
> +	struct intel_gt *gt = pxp_to_gt(pxp);
> +	u32 events = 0;
> +
> +	spin_lock_irq(&gt->irq_lock);
> +	events = fetch_and_zero(&pxp->session_events);
> +	spin_unlock_irq(&gt->irq_lock);
> +
> +	if (!events)
> +		return;
> +
> +	if (events & PXP_TERMINATION_REQUEST) {
> +		events &= ~PXP_TERMINATION_COMPLETE;
> +		pxp_terminate(pxp);
> +	}
> +
> +	if (events & PXP_TERMINATION_COMPLETE)
> +		pxp_terminate_complete(pxp);
> +}
> diff --git a/drivers/gpu/drm/i915/pxp/intel_pxp_session.h b/drivers/gpu/drm/i915/pxp/intel_pxp_session.h
> index 7354314b1cc4..ba4c9d2b94b7 100644
> --- a/drivers/gpu/drm/i915/pxp/intel_pxp_session.h
> +++ b/drivers/gpu/drm/i915/pxp/intel_pxp_session.h
> @@ -8,9 +8,8 @@
>  
>  #include <linux/types.h>
>  
> -struct intel_pxp;
> +struct work_struct;
>  
> -int intel_pxp_create_arb_session(struct intel_pxp *pxp);
> -int intel_pxp_terminate_arb_session_and_global(struct intel_pxp *pxp);
> +void intel_pxp_session_work(struct work_struct *work);
>  
>  #endif /* __INTEL_PXP_SESSION_H__ */
> diff --git a/drivers/gpu/drm/i915/pxp/intel_pxp_tee.c b/drivers/gpu/drm/i915/pxp/intel_pxp_tee.c
> index 98a62666b377..e3d178c44e51 100644
> --- a/drivers/gpu/drm/i915/pxp/intel_pxp_tee.c
> +++ b/drivers/gpu/drm/i915/pxp/intel_pxp_tee.c
> @@ -65,21 +65,21 @@ static int i915_pxp_tee_component_bind(struct device *i915_kdev,
>  {
>  	struct drm_i915_private *i915 = kdev_to_i915(i915_kdev);
>  	struct intel_pxp *pxp = i915_dev_to_pxp(i915_kdev);
> +	int ret;
>  
>  	pxp->pxp_component = data;
>  	pxp->pxp_component->tee_dev = tee_kdev;
>  
>  	/* the component is required to fully start the PXP HW */
>  	intel_pxp_init_hw(pxp);
> -
> -	if (!pxp->arb_is_valid) {
> +	ret = intel_pxp_wait_for_arb_start(pxp);
> +	if (ret) {
>  		drm_err(&i915->drm, "Failed to create arb session during bind\n");
>  		intel_pxp_fini_hw(pxp);
>  		pxp->pxp_component = NULL;
> -		return -EIO;
>  	}
>  
> -	return 0;
> +	return ret;
>  }
>  
>  static void i915_pxp_tee_component_unbind(struct device *i915_kdev,
> diff --git a/drivers/gpu/drm/i915/pxp/intel_pxp_types.h b/drivers/gpu/drm/i915/pxp/intel_pxp_types.h
> index 5f01eb3c3d2c..c059a17cbcfe 100644
> --- a/drivers/gpu/drm/i915/pxp/intel_pxp_types.h
> +++ b/drivers/gpu/drm/i915/pxp/intel_pxp_types.h
> @@ -6,7 +6,9 @@
>  #ifndef __INTEL_PXP_TYPES_H__
>  #define __INTEL_PXP_TYPES_H__
>  
> +#include <linux/completion.h>
>  #include <linux/types.h>
> +#include <linux/workqueue.h>
>  
>  struct intel_context;
>  struct i915_pxp_component;
> @@ -22,6 +24,22 @@ struct intel_pxp {
>  	 * session to know if it's valid and need to track the status in SW.
>  	 */
>  	bool arb_is_valid;
> +
> +	/*
> +	 * If the HW perceives an attack on the integrity of the encryption it
> +	 * will invalidate the keys and expect SW to re-initialize the session.
> +	 * We keep track of this state to make sure we only re-start the arb
> +	 * session when required.
> +	 */
> +	bool global_state_attacked;
> +
> +	bool irq_enabled;
> +	struct completion termination;
> +
> +	struct work_struct session_work;
> +	u32 session_events; /* protected with gt->irq_lock */
> +#define PXP_TERMINATION_REQUEST  BIT(0)
> +#define PXP_TERMINATION_COMPLETE BIT(1)
>  };
>  
>  #endif /* __INTEL_PXP_TYPES_H__ */
> -- 
> 2.29.2
> 
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