Re: [Intel-gfx] [PATCH v6 10/15] drm/i915/pxp: interfaces for using protected objects

Daniel Vetter
2021-08-16T15:29:12Z

On Fri, Aug 13, 2021 at 08:24:44AM -0700, Daniele Ceraolo Spurio wrote:
>
>
> On 8/13/2021 7:42 AM, Daniel Vetter wrote:
> > On Fri, Aug 13, 2021 at 04:37:53PM +0200, Daniel Vetter wrote:
> > > On Wed, Jul 28, 2021 at 07:01:01PM -0700, Daniele Ceraolo Spurio wrote:
> > > > This api allow user mode to create protected buffers and to mark
> > > > contexts as making use of such objects. Only when using contexts
> > > > marked in such a way is the execution guaranteed to work as expected.
> > > >
> > > > Contexts can only be marked as using protected content at creation time
> > > > (i.e. the parameter is immutable) and they must be both bannable and not
> > > > recoverable.
> > > >
> > > > All protected objects and contexts that have backing storage will be
> > > > considered invalid when the PXP session is destroyed and all new
> > > > submissions using them will be rejected. All intel contexts within the
> > > > invalidated gem contexts will be marked banned. A new flag has been
> > > > added to the RESET_STATS ioctl to report the context invalidation to
> > > > userspace.
> > > >
> > > > This patch was previously sent as 2 separate patches, which have been
> > > > squashed following a request to have all the uapi in a single patch.
> > > > I've retained the s-o-b from both.
> > > >
> > > > v5: squash patches, rebase on proto_ctx, update kerneldoc
> > > >
> > > > v6: rebase on obj create_ext changes
> > > >
> > > > Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
> > > > Signed-off-by: Bommu Krishnaiah <krishnaiah.bommu@intel.com>
> > > > Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
> > > > Cc: Chris Wilson <chris@chris-wilson.co.uk>
> > > > Cc: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
> > > > Cc: Jason Ekstrand <jason@jlekstrand.net>
> > > > Cc: Daniel Vetter <daniel.vetter@intel.com>
> > > > Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com> #v5
> > > > ---
> > > > drivers/gpu/drm/i915/gem/i915_gem_context.c | 68 ++++++++++++--
> > > > drivers/gpu/drm/i915/gem/i915_gem_context.h | 18 ++++
> > > > .../gpu/drm/i915/gem/i915_gem_context_types.h | 2 +
> > > > drivers/gpu/drm/i915/gem/i915_gem_create.c | 75 ++++++++++++----
> > > > .../gpu/drm/i915/gem/i915_gem_execbuffer.c | 40 ++++++++-
> > > > drivers/gpu/drm/i915/gem/i915_gem_object.c | 6 ++
> > > > drivers/gpu/drm/i915/gem/i915_gem_object.h | 12 +++
> > > > .../gpu/drm/i915/gem/i915_gem_object_types.h | 9 ++
> > > > drivers/gpu/drm/i915/pxp/intel_pxp.c | 89 +++++++++++++++++++
> > > > drivers/gpu/drm/i915/pxp/intel_pxp.h | 15 ++++
> > > > drivers/gpu/drm/i915/pxp/intel_pxp_session.c | 3 +
> > > > drivers/gpu/drm/i915/pxp/intel_pxp_types.h | 5 ++
> > > > include/uapi/drm/i915_drm.h | 55 +++++++++++-
> > > > 13 files changed, 371 insertions(+), 26 deletions(-)
> > > >
> > > > diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context.c b/drivers/gpu/drm/i915/gem/i915_gem_context.c
> > > > index cff72679ad7c..0cd3e2d06188 100644
> > > > --- a/drivers/gpu/drm/i915/gem/i915_gem_context.c
> > > > +++ b/drivers/gpu/drm/i915/gem/i915_gem_context.c
> > > > @@ -77,6 +77,8 @@
> > > > #include "gt/intel_gpu_commands.h"
> > > > #include "gt/intel_ring.h"
> > > > +#include "pxp/intel_pxp.h"
> > > > +
> > > > #include "i915_gem_context.h"
> > > > #include "i915_trace.h"
> > > > #include "i915_user_extensions.h"
> > > > @@ -241,6 +243,25 @@ static int proto_context_set_persistence(struct drm_i915_private *i915,
> > > > return 0;
> > > > }
> > > > +static int proto_context_set_protected(struct drm_i915_private *i915,
> > > > + struct i915_gem_proto_context *pc,
> > > > + bool protected)
> > > > +{
> > > > + int ret = 0;
> > > > +
> > > > + if (!intel_pxp_is_enabled(&i915->gt.pxp))
> > > > + ret = -ENODEV;
> > > > + else if (!protected)
> > > > + pc->user_flags &= ~BIT(UCONTEXT_PROTECTED);
> > > > + else if ((pc->user_flags & BIT(UCONTEXT_RECOVERABLE)) ||
> > > > + !(pc->user_flags & BIT(UCONTEXT_BANNABLE)))
> > > > + ret = -EPERM;
> > > > + else
> > > > + pc->user_flags |= BIT(UCONTEXT_PROTECTED);
> > > > +
> > > > + return ret;
> > > > +}
> > > > +
> > > > static struct i915_gem_proto_context *
> > > > proto_context_create(struct drm_i915_private *i915, unsigned int flags)
> > > > {
> > > > @@ -686,6 +707,8 @@ static int set_proto_ctx_param(struct drm_i915_file_private *fpriv,
> > > > ret = -EPERM;
> > > > else if (args->value)
> > > > pc->user_flags |= BIT(UCONTEXT_BANNABLE);
> > > > + else if (pc->user_flags & BIT(UCONTEXT_PROTECTED))
> > > > + ret = -EPERM;
> > > > else
> > > > pc->user_flags &= ~BIT(UCONTEXT_BANNABLE);
> > > > break;
> > > > @@ -693,10 +716,12 @@ static int set_proto_ctx_param(struct drm_i915_file_private *fpriv,
> > > > case I915_CONTEXT_PARAM_RECOVERABLE:
> > > > if (args->size)
> > > > ret = -EINVAL;
> > > > - else if (args->value)
> > > > - pc->user_flags |= BIT(UCONTEXT_RECOVERABLE);
> > > > - else
> > > > + else if (!args->value)
> > > > pc->user_flags &= ~BIT(UCONTEXT_RECOVERABLE);
> > > > + else if (pc->user_flags & BIT(UCONTEXT_PROTECTED))
> > > > + ret = -EPERM;
> > > > + else
> > > > + pc->user_flags |= BIT(UCONTEXT_RECOVERABLE);
> > > > break;
> > > > case I915_CONTEXT_PARAM_PRIORITY:
> > > > @@ -724,6 +749,11 @@ static int set_proto_ctx_param(struct drm_i915_file_private *fpriv,
> > > > args->value);
> > > > break;
> > > > + case I915_CONTEXT_PARAM_PROTECTED_CONTENT:
> > > > + ret = proto_context_set_protected(fpriv->dev_priv, pc,
> > > > + args->value);
> > > > + break;
> > > > +
> > > > case I915_CONTEXT_PARAM_NO_ZEROMAP:
> > > > case I915_CONTEXT_PARAM_BAN_PERIOD:
> > > > case I915_CONTEXT_PARAM_RINGSIZE:
> > > > @@ -1798,6 +1828,18 @@ static int set_priority(struct i915_gem_context *ctx,
> > > > return 0;
> > > > }
> > > > +static int get_protected(struct i915_gem_context *ctx,
> > > > + struct drm_i915_gem_context_param *args)
> > > > +{
> > > > + if (!intel_pxp_is_enabled(&ctx->i915->gt.pxp))
> > > > + return -ENODEV;
> > > > +
> > > > + args->size = 0;
> > > > + args->value = i915_gem_context_uses_protected_content(ctx);
> > > > +
> > > > + return 0;
> > > > +}
> > > > +
> > > > static int ctx_setparam(struct drm_i915_file_private *fpriv,
> > > > struct i915_gem_context *ctx,
> > > > struct drm_i915_gem_context_param *args)
> > > > @@ -1821,6 +1863,8 @@ static int ctx_setparam(struct drm_i915_file_private *fpriv,
> > > > ret = -EPERM;
> > > > else if (args->value)
> > > > i915_gem_context_set_bannable(ctx);
> > > > + else if (i915_gem_context_uses_protected_content(ctx))
> > > > + ret = -EPERM; /* can't clear this for protected contexts */
> > > > else
> > > > i915_gem_context_clear_bannable(ctx);
> > > > break;
> > > > @@ -1828,10 +1872,12 @@ static int ctx_setparam(struct drm_i915_file_private *fpriv,
> > > > case I915_CONTEXT_PARAM_RECOVERABLE:
> > > > if (args->size)
> > > > ret = -EINVAL;
> > > > - else if (args->value)
> > > > - i915_gem_context_set_recoverable(ctx);
> > > > - else
> > > > + else if (!args->value)
> > > > i915_gem_context_clear_recoverable(ctx);
> > > > + else if (i915_gem_context_uses_protected_content(ctx))
> > > > + ret = -EPERM; /* can't set this for protected contexts */
> > > > + else
> > > > + i915_gem_context_set_recoverable(ctx);
> > > > break;
> > > > case I915_CONTEXT_PARAM_PRIORITY:
> > > > @@ -1846,6 +1892,7 @@ static int ctx_setparam(struct drm_i915_file_private *fpriv,
> > > > ret = set_persistence(ctx, args);
> > > > break;
> > > > + case I915_CONTEXT_PARAM_PROTECTED_CONTENT:
> > > > case I915_CONTEXT_PARAM_NO_ZEROMAP:
> > > > case I915_CONTEXT_PARAM_BAN_PERIOD:
> > > > case I915_CONTEXT_PARAM_RINGSIZE:
> > > > @@ -2174,6 +2221,10 @@ int i915_gem_context_getparam_ioctl(struct drm_device *dev, void *data,
> > > > args->value = i915_gem_context_is_persistent(ctx);
> > > > break;
> > > > + case I915_CONTEXT_PARAM_PROTECTED_CONTENT:
> > > > + ret = get_protected(ctx, args);
> > > > + break;
> > > > +
> > > > case I915_CONTEXT_PARAM_NO_ZEROMAP:
> > > > case I915_CONTEXT_PARAM_BAN_PERIOD:
> > > > case I915_CONTEXT_PARAM_ENGINES:
> > > > @@ -2250,6 +2301,11 @@ int i915_gem_context_reset_stats_ioctl(struct drm_device *dev,
> > > > args->batch_active = atomic_read(&ctx->guilty_count);
> > > > args->batch_pending = atomic_read(&ctx->active_count);
> > > > + /* re-use args->flags for output flags */
> > > > + args->flags = 0;
> > > > + if (i915_gem_context_invalidated(ctx))
> > > > + args->flags |= I915_CONTEXT_INVALIDATED;
> > > > +
> > > > i915_gem_context_put(ctx);
> > > > return 0;
> > > > }
> > > > diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context.h b/drivers/gpu/drm/i915/gem/i915_gem_context.h
> > > > index 18060536b0c2..d932a70122fa 100644
> > > > --- a/drivers/gpu/drm/i915/gem/i915_gem_context.h
> > > > +++ b/drivers/gpu/drm/i915/gem/i915_gem_context.h
> > > > @@ -108,6 +108,24 @@ i915_gem_context_clear_user_engines(struct i915_gem_context *ctx)
> > > > clear_bit(CONTEXT_USER_ENGINES, &ctx->flags);
> > > > }
> > > > +static inline bool
> > > > +i915_gem_context_invalidated(const struct i915_gem_context *ctx)
> > > > +{
> > > > + return test_bit(CONTEXT_INVALID, &ctx->flags);
> > > > +}
> > > > +
> > > > +static inline void
> > > > +i915_gem_context_set_invalid(struct i915_gem_context *ctx)
> > > > +{
> > > > + set_bit(CONTEXT_INVALID, &ctx->flags);
> > > Do we _really_ need a new bit in this already very complex state
> > > machinery, and can't we reuse the BANNED flag instead?
> > >
> > > This ctx->flags is atomic, unorderd, and that means you need barriers and
> > > everything.
> > >
> > > If you don't actually need the atomic state bit machinery because you're
> > > using simple locking, then pls use your own boolean, and document by which
> > > lock it's protected.
> > >
> > > > +}
> > > > +
> > > > +static inline bool
> > > > +i915_gem_context_uses_protected_content(const struct i915_gem_context *ctx)
> > > > +{
> > > > + return test_bit(UCONTEXT_PROTECTED, &ctx->user_flags);
> > > For immutable state (I really hope this is immutable) pls don't reuse the
> > > atomic bitfield of mutable state, but create a flag of your own.
> > >
> > > Also please document all the rules around how this is set/changed in the
> > > kerneldoc header comments for the data structure. Finally if you never set
> > > it except at creation.
> > >
> > > > +}
> > > > +
> > > > /* i915_gem_context.c */
> > > > void i915_gem_init__contexts(struct drm_i915_private *i915);
> > > > diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context_types.h b/drivers/gpu/drm/i915/gem/i915_gem_context_types.h
> > > > index 94c03a97cb77..1aa2290aa3c7 100644
> > > > --- a/drivers/gpu/drm/i915/gem/i915_gem_context_types.h
> > > > +++ b/drivers/gpu/drm/i915/gem/i915_gem_context_types.h
> > > > @@ -301,6 +301,7 @@ struct i915_gem_context {
> > > > #define UCONTEXT_BANNABLE 2
> > > > #define UCONTEXT_RECOVERABLE 3
> > > > #define UCONTEXT_PERSISTENCE 4
> > > > +#define UCONTEXT_PROTECTED 5
> > > > /**
> > > > * @flags: small set of booleans
> > > > @@ -308,6 +309,7 @@ struct i915_gem_context {
> > > > unsigned long flags;
> > > > #define CONTEXT_CLOSED 0
> > > > #define CONTEXT_USER_ENGINES 1
> > > > +#define CONTEXT_INVALID 2
> > > > /** @mutex: guards everything that isn't engines or handles_vma */
> > > > struct mutex mutex;
> > > > diff --git a/drivers/gpu/drm/i915/gem/i915_gem_create.c b/drivers/gpu/drm/i915/gem/i915_gem_create.c
> > > > index 23fee13a3384..0e48629316bb 100644
> > > > --- a/drivers/gpu/drm/i915/gem/i915_gem_create.c
> > > > +++ b/drivers/gpu/drm/i915/gem/i915_gem_create.c
> > > > @@ -6,6 +6,7 @@
> > > > #include "gem/i915_gem_ioctls.h"
> > > > #include "gem/i915_gem_lmem.h"
> > > > #include "gem/i915_gem_region.h"
> > > > +#include "pxp/intel_pxp.h"
> > > > #include "i915_drv.h"
> > > > #include "i915_trace.h"
> > > > @@ -82,21 +83,11 @@ static int i915_gem_publish(struct drm_i915_gem_object *obj,
> > > > return 0;
> > > > }
> > > > -/**
> > > > - * Creates a new object using the same path as DRM_I915_GEM_CREATE_EXT
> > > > - * @i915: i915 private
> > > > - * @size: size of the buffer, in bytes
> > > > - * @placements: possible placement regions, in priority order
> > > > - * @n_placements: number of possible placement regions
> > > > - *
> > > > - * This function is exposed primarily for selftests and does very little
> > > > - * error checking. It is assumed that the set of placement regions has
> > > > - * already been verified to be valid.
> > > > - */
> > > > -struct drm_i915_gem_object *
> > > > -__i915_gem_object_create_user(struct drm_i915_private *i915, u64 size,
> > > > - struct intel_memory_region **placements,
> > > > - unsigned int n_placements)
> > > > +static struct drm_i915_gem_object *
> > > > +__i915_gem_object_create_user_ext(struct drm_i915_private *i915, u64 size,
> > > > + struct intel_memory_region **placements,
> > > > + unsigned int n_placements,
> > > > + unsigned int ext_flags)
> > > > {
> > > > struct intel_memory_region *mr = placements[0];
> > > > struct drm_i915_gem_object *obj;
> > > > @@ -135,6 +126,12 @@ __i915_gem_object_create_user(struct drm_i915_private *i915, u64 size,
> > > > GEM_BUG_ON(size != obj->base.size);
> > > > + /* Add any flag set by create_ext options */
> > > > + flags |= ext_flags;
> > > > +
> > > > + if (i915_gem_object_is_protected(obj))
> > > > + intel_pxp_object_add(obj);
> > > > +
> > > > trace_i915_gem_object_create(obj);
> > > > return obj;
> > > > @@ -145,6 +142,26 @@ __i915_gem_object_create_user(struct drm_i915_private *i915, u64 size,
> > > > return ERR_PTR(ret);
> > > > }
> > > > +/**
> > > > + * Creates a new object using the same path as DRM_I915_GEM_CREATE_EXT
> > > > + * @i915: i915 private
> > > > + * @size: size of the buffer, in bytes
> > > > + * @placements: possible placement regions, in priority order
> > > > + * @n_placements: number of possible placement regions
> > > > + *
> > > > + * This function is exposed primarily for selftests and does very little
> > > > + * error checking. It is assumed that the set of placement regions has
> > > > + * already been verified to be valid.
> > > > + */
> > > > +struct drm_i915_gem_object *
> > > > +__i915_gem_object_create_user(struct drm_i915_private *i915, u64 size,
> > > > + struct intel_memory_region **placements,
> > > > + unsigned int n_placements)
> > > > +{
> > > > + return __i915_gem_object_create_user_ext(i915, size, placements,
> > > > + n_placements, 0);
> > > > +}
> > > > +
> > > > int
> > > > i915_gem_dumb_create(struct drm_file *file,
> > > > struct drm_device *dev,
> > > > @@ -224,6 +241,7 @@ struct create_ext {
> > > > struct drm_i915_private *i915;
> > > > struct intel_memory_region *placements[INTEL_REGION_UNKNOWN];
> > > > unsigned int n_placements;
> > > > + unsigned long flags;
> > > > };
> > > > static void repr_placements(char *buf, size_t size,
> > > > @@ -356,8 +374,28 @@ static int ext_set_placements(struct i915_user_extension __user *base,
> > > > return set_placements(&ext, data);
> > > > }
> > > > +static int ext_set_protected(struct i915_user_extension __user *base, void *data)
> > > > +{
> > > > + struct drm_i915_gem_create_ext_protected_content ext;
> > > > + struct create_ext *ext_data = data;
> > > > +
> > > > + if (copy_from_user(&ext, base, sizeof(ext)))
> > > > + return -EFAULT;
> > > > +
> > > > + if (ext.flags)
> > > > + return -EINVAL;
> > > > +
> > > > + if (!intel_pxp_is_enabled(&ext_data->i915->gt.pxp))
> > > > + return -ENODEV;
> > > > +
> > > > + ext_data->flags |= I915_BO_PROTECTED;
> > > > +
> > > > + return 0;
> > > > +}
> > > > +
> > > > static const i915_user_extension_fn create_extensions[] = {
> > > > [I915_GEM_CREATE_EXT_MEMORY_REGIONS] = ext_set_placements,
> > > > + [I915_GEM_CREATE_EXT_PROTECTED_CONTENT] = ext_set_protected,
> > > > };
> > > > /**
> > > > @@ -392,9 +430,10 @@ i915_gem_create_ext_ioctl(struct drm_device *dev, void *data,
> > > > ext_data.n_placements = 1;
> > > > }
> > > > - obj = __i915_gem_object_create_user(i915, args->size,
> > > > - ext_data.placements,
> > > > - ext_data.n_placements);
> > > > + obj = __i915_gem_object_create_user_ext(i915, args->size,
> > > > + ext_data.placements,
> > > > + ext_data.n_placements,
> > > > + ext_data.flags);
> > > > if (IS_ERR(obj))
> > > > return PTR_ERR(obj);
> > > > diff --git a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
> > > > index 1ed7475de454..04f33d163340 100644
> > > > --- a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
> > > > +++ b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
> > > > @@ -21,6 +21,8 @@
> > > > #include "gt/intel_gt_pm.h"
> > > > #include "gt/intel_ring.h"
> > > > +#include "pxp/intel_pxp.h"
> > > > +
> > > > #include "i915_drv.h"
> > > > #include "i915_gem_clflush.h"
> > > > #include "i915_gem_context.h"
> > > > @@ -751,6 +753,11 @@ static int eb_select_context(struct i915_execbuffer *eb)
> > > > if (unlikely(IS_ERR(ctx)))
> > > > return PTR_ERR(ctx);
> > > > + if (i915_gem_context_invalidated(ctx)) {
> > > > + i915_gem_context_put(ctx);
> > > > + return -EACCES;
> > > > + }
> > > > +
> > > > eb->gem_context = ctx;
> > > > if (rcu_access_pointer(ctx->vm))
> > > > eb->invalid_flags |= EXEC_OBJECT_NEEDS_GTT;
> > > > @@ -819,7 +826,7 @@ static struct i915_vma *eb_lookup_vma(struct i915_execbuffer *eb, u32 handle)
> > > > do {
> > > > struct drm_i915_gem_object *obj;
> > > > struct i915_vma *vma;
> > > > - int err;
> > > > + int err = 0;
> > > > rcu_read_lock();
> > > > vma = radix_tree_lookup(&eb->gem_context->handles_vma, handle);
> > > > @@ -833,6 +840,26 @@ static struct i915_vma *eb_lookup_vma(struct i915_execbuffer *eb, u32 handle)
> > > > if (unlikely(!obj))
> > > > return ERR_PTR(-ENOENT);
> > > > + /*
> > > > + * If the user has opted-in for protected-object tracking, make
> > > > + * sure the object encryption can be used.
> > > > + * We only need to do this when the object is first used with
> > > > + * this context, because the context itself will be banned when
> > > > + * the protected objects become invalid.
> > > > + */
> > > > + if (i915_gem_context_uses_protected_content(eb->gem_context) &&
> > > > + i915_gem_object_is_protected(obj)) {
> > > > + if (!intel_pxp_is_active(&vm->gt->pxp))
> > > > + err = -ENODEV;
> > > > + else if (!i915_gem_object_has_valid_protection(obj))
> > > > + err = -ENOEXEC;
> > > > +
> > > > + if (err) {
> > > > + i915_gem_object_put(obj);
> > > > + return ERR_PTR(err);
> > > > + }
> > > > + }
> > > > +
> > > > vma = i915_vma_instance(obj, vm, NULL);
> > > > if (IS_ERR(vma)) {
> > > > i915_gem_object_put(obj);
> > > > @@ -2752,6 +2779,17 @@ eb_select_engine(struct i915_execbuffer *eb)
> > > > intel_gt_pm_get(ce->engine->gt);
> > > > + if (i915_gem_context_uses_protected_content(eb->gem_context)) {
> > > > + err = intel_pxp_wait_for_arb_start(&ce->engine->gt->pxp);
> > > > + if (err)
> > > > + goto err;
> > > > +
> > > > + if (i915_gem_context_invalidated(eb->gem_context)) {
> > > > + err = -EACCES;
> > > Shouldn't the normal banned context handling takee care of anything that
> > > slips through? Rolling your own racy invalidation checks doesn't look like
> > > a good idea.
> > >
> > > > + goto err;
> > > > + }
> > > > + }
> > > > +
> > > > if (!test_bit(CONTEXT_ALLOC_BIT, &ce->flags)) {
> > > > err = intel_context_alloc_state(ce);
> > > > if (err)
> > > > diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object.c b/drivers/gpu/drm/i915/gem/i915_gem_object.c
> > > > index 6fb9afb65034..658a42a7fa07 100644
> > > > --- a/drivers/gpu/drm/i915/gem/i915_gem_object.c
> > > > +++ b/drivers/gpu/drm/i915/gem/i915_gem_object.c
> > > > @@ -25,6 +25,7 @@
> > > > #include <linux/sched/mm.h>
> > > > #include "display/intel_frontbuffer.h"
> > > > +#include "pxp/intel_pxp.h"
> > > > #include "i915_drv.h"
> > > > #include "i915_gem_clflush.h"
> > > > #include "i915_gem_context.h"
> > > > @@ -73,6 +74,8 @@ void i915_gem_object_init(struct drm_i915_gem_object *obj,
> > > > INIT_LIST_HEAD(&obj->lut_list);
> > > > spin_lock_init(&obj->lut_lock);
> > > > + INIT_LIST_HEAD(&obj->pxp_link);
> > > > +
> > > > spin_lock_init(&obj->mmo.lock);
> > > > obj->mmo.offsets = RB_ROOT;
> > > > @@ -231,6 +234,9 @@ void __i915_gem_free_object(struct drm_i915_gem_object *obj)
> > > > spin_unlock(&obj->vma.lock);
> > > > }
> > > > + if (i915_gem_object_has_valid_protection(obj))
> > > > + intel_pxp_object_remove(obj);
> > > > +
> > > > __i915_gem_object_free_mmaps(obj);
> > > > GEM_BUG_ON(!list_empty(&obj->lut_list));
> > > > diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object.h b/drivers/gpu/drm/i915/gem/i915_gem_object.h
> > > > index 48112b9d76df..137ae2723514 100644
> > > > --- a/drivers/gpu/drm/i915/gem/i915_gem_object.h
> > > > +++ b/drivers/gpu/drm/i915/gem/i915_gem_object.h
> > > > @@ -269,6 +269,18 @@ i915_gem_object_clear_tiling_quirk(struct drm_i915_gem_object *obj)
> > > > clear_bit(I915_TILING_QUIRK_BIT, &obj->flags);
> > > > }
> > > > +static inline bool
> > > > +i915_gem_object_is_protected(const struct drm_i915_gem_object *obj)
> > > > +{
> > > > + return obj->flags & I915_BO_PROTECTED;
> > > > +}
> > > > +
> > > > +static inline bool
> > > > +i915_gem_object_has_valid_protection(const struct drm_i915_gem_object *obj)
> > > > +{
> > > > + return i915_gem_object_is_protected(obj) && !list_empty(&obj->pxp_link);
> > > > +}
> > > > +
> > > > static inline bool
> > > > i915_gem_object_type_has(const struct drm_i915_gem_object *obj,
> > > > unsigned long flags)
> > > > diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object_types.h b/drivers/gpu/drm/i915/gem/i915_gem_object_types.h
> > > > index 2471f36aaff3..38e4a190607a 100644
> > > > --- a/drivers/gpu/drm/i915/gem/i915_gem_object_types.h
> > > > +++ b/drivers/gpu/drm/i915/gem/i915_gem_object_types.h
> > > > @@ -298,6 +298,7 @@ struct drm_i915_gem_object {
> > > > I915_BO_ALLOC_USER)
> > > > #define I915_BO_READONLY BIT(4)
> > > > #define I915_TILING_QUIRK_BIT 5 /* unknown swizzling; do not release! */
> > > > +#define I915_BO_PROTECTED BIT(6)
> > > > /**
> > > > * @mem_flags - Mutable placement-related flags
> > > > @@ -537,6 +538,14 @@ struct drm_i915_gem_object {
> > > > bool created:1;
> > > > } ttm;
> > > > + /*
> > > > + * When the PXP session is invalidated, we need to mark all protected
> > > > + * objects as invalid. To easily do so we add them all to a list. The
> > > > + * presence on the list is used to check if the encryption is valid or
> > > > + * not.
> > > > + */
> > > > + struct list_head pxp_link;
> > This
> > - seems to be accessed locklessly, which needs giant amounts of comments
> > and justifications to prove a) it's needed and b) it's correct against
> > all races
> > - we already have a per-object lock in the form of dma_resv_lock. Why
> > can't we use that to protect pxp object state?
>
> This is always modified under pxp->lock. The only lockless access we do is a
> list_empty() check to see if the protection is valid, and that's because the
> check is inherently racy anyway (state can change at any point before or
> after we've checked) so adding a lock wouldn't really help. Note that the
> list can only be set at object creation time and it is only cleared either
> during the first invalidation or during object destruction.

Yeah, but every time we have races you need to think through whether
really nothing bad can ever happen. I pondered this a bit and came up with
the following idea:
- every time we get a pxp reset, we increment a generation counter. That
should never race, because we should be able to sufficiently protect pxp
state with some mutext.

- when we allocate a protect context or a protected buffer, we remember
the current generation counter. This can race, but also, it doesn't
matter because userspace is supposed allocate buffers after the context
was allocated. This pxp_generation is invariant over the lifetime of an
object/context, at least for now. We can sample this pxp_generation
holding the same lock as the pxp reset, which avoids another pile of
potentially confusion races.

- for execbuf context side we entirely rely on the existing context
banning.

- for the buffer objects we compare the object's pxp_generation against
the contexts. If they don't match we fail.

This means no locking to protected this, no additional races to ponder.
Also pretty easy way reset a buffer for the non-robust version (if that
ever happens), we just update the pxp_generation.
-Daniel

>
> Daniele
>
> > Looking needs to be done with extreme care, or we're just burrying
> > ourselves into something that cannot be understood and maintained anymore.
> > -Daniel
> >
> > > > +
> > > > /** Record of address bit 17 of each page at last unbind. */
> > > > unsigned long *bit_17;
> > > > diff --git a/drivers/gpu/drm/i915/pxp/intel_pxp.c b/drivers/gpu/drm/i915/pxp/intel_pxp.c
> > > > index b0c7edc10cc3..f418281e8c10 100644
> > > > --- a/drivers/gpu/drm/i915/pxp/intel_pxp.c
> > > > +++ b/drivers/gpu/drm/i915/pxp/intel_pxp.c
> > > > @@ -7,6 +7,7 @@
> > > > #include "intel_pxp_irq.h"
> > > > #include "intel_pxp_session.h"
> > > > #include "intel_pxp_tee.h"
> > > > +#include "gem/i915_gem_context.h"
> > > > #include "gt/intel_context.h"
> > > > #include "i915_drv.h"
> > > > @@ -70,6 +71,9 @@ void intel_pxp_init(struct intel_pxp *pxp)
> > > > mutex_init(&pxp->tee_mutex);
> > > > + spin_lock_init(&pxp->lock);
> > > > + INIT_LIST_HEAD(&pxp->protected_objects);
> > > > +
> > > > /*
> > > > * 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
> > > > @@ -166,3 +170,88 @@ void intel_pxp_fini_hw(struct intel_pxp *pxp)
> > > > intel_pxp_irq_disable(pxp);
> > > > }
> > > > +
> > > > +int intel_pxp_object_add(struct drm_i915_gem_object *obj)
> > > > +{
> > > > + struct intel_pxp *pxp = &to_i915(obj->base.dev)->gt.pxp;
> > > > +
> > > > + if (!intel_pxp_is_enabled(pxp))
> > > > + return -ENODEV;
> > > > +
> > > > + if (!list_empty(&obj->pxp_link))
> > > > + return -EEXIST;
> > > > +
> > > > + spin_lock_irq(&pxp->lock);
> > > > + list_add(&obj->pxp_link, &pxp->protected_objects);
> > > > + spin_unlock_irq(&pxp->lock);
> > > > +
> > > > + return 0;
> > > > +}
> > > > +
> > > > +void intel_pxp_object_remove(struct drm_i915_gem_object *obj)
> > > > +{
> > > > + struct intel_pxp *pxp = &to_i915(obj->base.dev)->gt.pxp;
> > > > +
> > > > + if (!intel_pxp_is_enabled(pxp))
> > > > + return;
> > > > +
> > > > + spin_lock_irq(&pxp->lock);
> > > > + list_del_init(&obj->pxp_link);
> > > > + spin_unlock_irq(&pxp->lock);
> > > > +}
> > > > +
> > > > +void intel_pxp_invalidate(struct intel_pxp *pxp)
> > > There is a lot of locking going on here. Please make sure it's all
> > > properly documented what the rules are in kerneldoc, even for existing
> > > stuff.
> > >
> > > Especially anytime there's anything tricky going on, like:
> > > - kref_get_unless_zero
> > > - test_bit (that's an unorderd atomic, so either you don't actually need
> > > the atomic, or you need a pile of barriers and comments about them)
> > > - hiddent atomic ops like intel_context_set_banned or
> > > i915_gem_context_set_invalid also need great care, least because the
> > > current rules aren't documented really. So step one here before using
> > > them is documenting the rules of how banning works.
> > >
> > > > +{
> > > > + struct drm_i915_private *i915 = pxp_to_gt(pxp)->i915;
> > > > + struct drm_i915_gem_object *obj, *tmp;
> > > > + struct i915_gem_context *ctx, *cn;
> > > > +
> > > > + /* delete objects that have been used with the invalidated session */
> > > > + spin_lock_irq(&pxp->lock);
> > > > + list_for_each_entry_safe(obj, tmp, &pxp->protected_objects, pxp_link) {
> > > > + if (i915_gem_object_has_pages(obj))
> > > > + list_del_init(&obj->pxp_link);
> > We have a per
> > > > + }
> > > > + spin_unlock_irq(&pxp->lock);
> > > > +
> > > > + /* ban all contexts marked as protected */
> > > > + spin_lock_irq(&i915->gem.contexts.lock);
> > > > + list_for_each_entry_safe(ctx, cn, &i915->gem.contexts.list, link) {
> > > > + struct i915_gem_engines_iter it;
> > > > + struct intel_context *ce;
> > > > +
> > > > + if (!kref_get_unless_zero(&ctx->ref))
> > > > + continue;
> > > > +
> > > > + if (likely(!i915_gem_context_uses_protected_content(ctx)) ||
> > > > + i915_gem_context_invalidated(ctx)) {
> > > > + i915_gem_context_put(ctx);
> > > > + continue;
> > > > + }
> > > > +
> > > > + spin_unlock_irq(&i915->gem.contexts.lock);
> > > > +
> > > > + /*
> > > > + * Note that by the time we get here the HW keys are already
> > > > + * long gone, so any batch using them that's already on the
> > > > + * engines is very likely a lost cause (and it has probably
> > > > + * already hung the engine). Therefore, we skip attempting to
> > > > + * pull the running context out of the HW and we prioritize
> > > > + * bringing the session back as soon as possible.
> > > > + */
> > > > + for_each_gem_engine(ce, i915_gem_context_lock_engines(ctx), it) {
> > > > + /* only invalidate if at least one ce was allocated */
> > > > + if (test_bit(CONTEXT_ALLOC_BIT, &ce->flags)) {
> > > > + intel_context_set_banned(ce);
> > > > + i915_gem_context_set_invalid(ctx);
> > > > + }
> > > > + }
> > > > + i915_gem_context_unlock_engines(ctx);
> > > > +
> > > > + spin_lock_irq(&i915->gem.contexts.lock);
> > > > + list_safe_reset_next(ctx, cn, link);
> > > > + i915_gem_context_put(ctx);
> > > > + }
> > > > + spin_unlock_irq(&i915->gem.contexts.lock);
> > > > +}
> > > > +
> > > > diff --git a/drivers/gpu/drm/i915/pxp/intel_pxp.h b/drivers/gpu/drm/i915/pxp/intel_pxp.h
> > > > index 074b3b980957..4f7647f34153 100644
> > > > --- a/drivers/gpu/drm/i915/pxp/intel_pxp.h
> > > > +++ b/drivers/gpu/drm/i915/pxp/intel_pxp.h
> > > > @@ -9,6 +9,8 @@
> > > > #include "gt/intel_gt_types.h"
> > > > #include "intel_pxp_types.h"
> > > > +struct drm_i915_gem_object;
> > > > +
> > > > static inline struct intel_gt *pxp_to_gt(const struct intel_pxp *pxp)
> > > > {
> > > > return container_of(pxp, struct intel_gt, pxp);
> > > > @@ -33,6 +35,11 @@ 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);
> > > > +
> > > > +int intel_pxp_object_add(struct drm_i915_gem_object *obj);
> > > > +void intel_pxp_object_remove(struct drm_i915_gem_object *obj);
> > > > +
> > > > +void intel_pxp_invalidate(struct intel_pxp *pxp);
> > > > #else
> > > > static inline void intel_pxp_init(struct intel_pxp *pxp)
> > > > {
> > > > @@ -46,6 +53,14 @@ static inline int intel_pxp_wait_for_arb_start(struct intel_pxp *pxp)
> > > > {
> > > > return 0;
> > > > }
> > > > +
> > > > +static inline int intel_pxp_object_add(struct drm_i915_gem_object *obj)
> > > > +{
> > > > + return 0;
> > > > +}
> > > > +static inline void intel_pxp_object_remove(struct drm_i915_gem_object *obj)
> > > > +{
> > > > +}
> > > > #endif
> > > > #endif /* __INTEL_PXP_H__ */
> > > > diff --git a/drivers/gpu/drm/i915/pxp/intel_pxp_session.c b/drivers/gpu/drm/i915/pxp/intel_pxp_session.c
> > > > index 67c30e534d50..0edd563a653d 100644
> > > > --- a/drivers/gpu/drm/i915/pxp/intel_pxp_session.c
> > > > +++ b/drivers/gpu/drm/i915/pxp/intel_pxp_session.c
> > > > @@ -85,6 +85,9 @@ static int pxp_terminate_arb_session_and_global(struct intel_pxp *pxp)
> > > > /* must mark termination in progress calling this function */
> > > > GEM_WARN_ON(pxp->arb_is_valid);
> > > > + /* invalidate protected objects */
> > > > + intel_pxp_invalidate(pxp);
> > > > +
> > > > /* terminate the hw sessions */
> > > > ret = intel_pxp_terminate_session(pxp, ARB_SESSION);
> > > > if (ret) {
> > > > diff --git a/drivers/gpu/drm/i915/pxp/intel_pxp_types.h b/drivers/gpu/drm/i915/pxp/intel_pxp_types.h
> > > > index 475e3312c287..be2bed3a2e4e 100644
> > > > --- a/drivers/gpu/drm/i915/pxp/intel_pxp_types.h
> > > > +++ b/drivers/gpu/drm/i915/pxp/intel_pxp_types.h
> > > > @@ -7,7 +7,9 @@
> > > > #define __INTEL_PXP_TYPES_H__
> > > > #include <linux/completion.h>
> > > > +#include <linux/list.h>
> > > > #include <linux/mutex.h>
> > > > +#include <linux/spinlock.h>
> > > > #include <linux/types.h>
> > > > #include <linux/workqueue.h>
> > > > @@ -43,6 +45,9 @@ struct intel_pxp {
> > > > u32 session_events; /* protected with gt->irq_lock */
> > > > #define PXP_TERMINATION_REQUEST BIT(0)
> > > > #define PXP_TERMINATION_COMPLETE BIT(1)
> > > > +
> > > > + spinlock_t lock; /* protects the objects list */
> > > > + struct list_head protected_objects;
> > > > };
> > > > #endif /* __INTEL_PXP_TYPES_H__ */
> > > > diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h
> > > > index 4393eef59d9b..2c9febdae6a5 100644
> > > > --- a/include/uapi/drm/i915_drm.h
> > > > +++ b/include/uapi/drm/i915_drm.h
> > > > @@ -1843,12 +1843,32 @@ struct drm_i915_gem_context_param {
> > > > * attempted to use it, never re-use this context param number.
> > > > */
> > > > #define I915_CONTEXT_PARAM_RINGSIZE 0xc
> > > > +
> > > > +/*
> > > > + * I915_CONTEXT_PARAM_PROTECTED_CONTENT:
> > > > + *
> > > > + * Mark that the context makes use of protected content, which will result
> > > > + * in the context being invalidated when the protected content session is. The
> > > > + * invalidation is reported back to userspace via the RESET_STATS ioctl (see
> > > > + * relevant doc for details).
> > > > + * This flag can only be set at context creation time and, when set to true,
> > > > + * must be preceded by an explicit setting of I915_CONTEXT_PARAM_RECOVERABLE
> > > > + * to false. This flag can't be set to true in conjunction with setting the
> > > > + * I915_CONTEXT_PARAM_BANNABLE flag to false.
> > > > + *
> > > > + * In addition to the normal failure cases, setting this flag during context
> > > > + * creation can result in the following errors:
> > > > + *
> > > > + * -ENODEV: feature not available
> > > > + * -EPERM: trying to mark a recoverable or not bannable context as protected
> > > > + */
> > > > +#define I915_CONTEXT_PARAM_PROTECTED_CONTENT 0xd
> > > > /* Must be kept compact -- no holes and well documented */
> > > > __u64 value;
> > > > };
> > > > -/*
> > > > +/**
> > > > * Context SSEU programming
> > > > *
> > > > * It may be necessary for either functional or performance reason to configure
> > > > @@ -2181,6 +2201,12 @@ struct drm_i915_reg_read {
> > > > struct drm_i915_reset_stats {
> > > > __u32 ctx_id;
> > > > __u32 flags;
> > > > + /*
> > > > + * contexts marked as using protected content are invalidated when the
> > > > + * protected content session dies. Submission of invalidated contexts
> > > > + * is rejected with -EACCES.
> > > > + */
> > > > +#define I915_CONTEXT_INVALIDATED 0x1
> > > > /* All resets since boot/module reload, for all contexts */
> > > > __u32 reset_count;
> > > > @@ -2959,8 +2985,12 @@ struct drm_i915_gem_create_ext {
> > > > *
> > > > * For I915_GEM_CREATE_EXT_MEMORY_REGIONS usage see
> > > > * struct drm_i915_gem_create_ext_memory_regions.
> > > > + *
> > > > + * For I915_GEM_CREATE_EXT_PROTECTED_CONTENT usage see
> > > > + * struct drm_i915_gem_create_ext_protected_content.
> > > > */
> > > > #define I915_GEM_CREATE_EXT_MEMORY_REGIONS 0
> > > > +#define I915_GEM_CREATE_EXT_PROTECTED_CONTENT 1
> > > > __u64 extensions;
> > > > };
> > > > @@ -3018,6 +3048,29 @@ struct drm_i915_gem_create_ext_memory_regions {
> > > > __u64 regions;
> > > > };
> > > > +/**
> > > > + * struct drm_i915_gem_create_ext_protected_content - The
> > > > + * I915_OBJECT_PARAM_PROTECTED_CONTENT extension.
> > > > + *
> > > > + * If this extension is provided, buffer contents are expected to be protected
> > > > + * by PXP encryption and require decryption for scan out and processing. This
> > > > + * is only possible on platforms that have PXP enabled, on all other scenarios
> > > > + * using this extension will cause the ioctl to fail and return -ENODEV. The
> > > > + * flags parameter is reserved for future expansion and must currently be set
> > > > + * to zero.
> > > > + *
> > > > + * The buffer contents are considered invalid after a PXP session teardown.
> > > > + *
> > > > + * The encryption is guaranteed to be processed correctly only if the object
> > > > + * is submitted with a context created using the
> > > > + * I915_CONTEXT_PARAM_PROTECTED_CONTENT flag. This will also enable extra checks
> > > > + * at submission time on the validity of the objects involved.
> > > > + */
> > > > +struct drm_i915_gem_create_ext_protected_content {
> > > > + struct i915_user_extension base;
> > > > + __u32 flags;
> > > > +};
> > > > +
> > > > /* ID of the protected content session managed by i915 when PXP is active */
> > > > #define I915_PROTECTED_CONTENT_DEFAULT_SESSION 0xf
> > > > --
> > > > 2.32.0
> > > >
> > > > _______________________________________________
> > > > Intel-gfx mailing list
> > > > Intel-gfx@lists.freedesktop.org
> > > > https://lists.freedesktop.org/mailman/listinfo/intel-gfx
> > > --
> > > Daniel Vetter
> > > Software Engineer, Intel Corporation
> > > http://blog.ffwll.ch
>

--
Daniel Vetter
Software Engineer, Intel Corporation