| Message ID | 1448630935-27377-1-git-send-email-chris@chris-wilson.co.uk (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Chris Wilson <chris@chris-wilson.co.uk> writes: > Following a GPU reset, we may leave the context in a poorly defined > state, and reloading from that context will leave the GPU flummoxed. For > secondary contexts, this will lead to that context being banned - but > currently it is also causing the default context to become banned, > leading to turmoil in the shared state. > > This is a regression from > > commit 6702cf16e0ba8b0129f5aa1b6609d4e9c70bc13b [v4.1] > Author: Ben Widawsky <benjamin.widawsky@intel.com> > Date: Mon Mar 16 16:00:58 2015 +0000 > > drm/i915: Initialize all contexts > > which quietly introduced the removal of the MI_RESTORE_INHIBIT on the > default context. > > v2: Mark the global default context as uninitialized on GPU reset so > that the context-local workarounds are reloaded upon re-enabling. > > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com> > Cc: Michel Thierry <michel.thierry@intel.com> > Cc: Mika Kuoppala <mika.kuoppala@intel.com> > Cc: Daniel Vetter <daniel.vetter@ffwll.ch> > --- > drivers/gpu/drm/i915/i915_gem_context.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c > index 43761c5bcaca..f024d5d2c746 100644 > --- a/drivers/gpu/drm/i915/i915_gem_context.c > +++ b/drivers/gpu/drm/i915/i915_gem_context.c > @@ -340,6 +340,10 @@ void i915_gem_context_reset(struct drm_device *dev) > i915_gem_context_unreference(lctx); > ring->last_context = NULL; > } > + > + /* Force the GPU state to be reinitialised on enabling */ > + if (ring->default_context) > + ring->default_context->legacy_hw_ctx.initialized = false; > } > } > > @@ -708,7 +712,7 @@ static int do_switch(struct drm_i915_gem_request *req) > if (ret) > goto unpin_out; > > - if (!to->legacy_hw_ctx.initialized) { > + if (!to->legacy_hw_ctx.initialized || i915_gem_context_is_default(to)) { > hw_flags |= MI_RESTORE_INHIBIT; > /* NB: If we inhibit the restore, the context is not allowed to > * die because future work may end up depending on valid address > -- > 2.6.2 > > _______________________________________________ > Intel-gfx mailing list > Intel-gfx@lists.freedesktop.org > http://lists.freedesktop.org/mailman/listinfo/intel-gfx
On Thu, Dec 10, 2015 at 12:19:29PM +0200, Mika Kuoppala wrote: > Chris Wilson <chris@chris-wilson.co.uk> writes: > > > Following a GPU reset, we may leave the context in a poorly defined > > state, and reloading from that context will leave the GPU flummoxed. For > > secondary contexts, this will lead to that context being banned - but > > currently it is also causing the default context to become banned, > > leading to turmoil in the shared state. > > > > This is a regression from > > > > commit 6702cf16e0ba8b0129f5aa1b6609d4e9c70bc13b [v4.1] > > Author: Ben Widawsky <benjamin.widawsky@intel.com> > > Date: Mon Mar 16 16:00:58 2015 +0000 > > > > drm/i915: Initialize all contexts > > > > which quietly introduced the removal of the MI_RESTORE_INHIBIT on the > > default context. > > > > v2: Mark the global default context as uninitialized on GPU reset so > > that the context-local workarounds are reloaded upon re-enabling. > > > > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> > > Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com> Queued for -next, thanks for the patch. -Daniel > > > Cc: Michel Thierry <michel.thierry@intel.com> > > Cc: Mika Kuoppala <mika.kuoppala@intel.com> > > Cc: Daniel Vetter <daniel.vetter@ffwll.ch> > > --- > > drivers/gpu/drm/i915/i915_gem_context.c | 6 +++++- > > 1 file changed, 5 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c > > index 43761c5bcaca..f024d5d2c746 100644 > > --- a/drivers/gpu/drm/i915/i915_gem_context.c > > +++ b/drivers/gpu/drm/i915/i915_gem_context.c > > @@ -340,6 +340,10 @@ void i915_gem_context_reset(struct drm_device *dev) > > i915_gem_context_unreference(lctx); > > ring->last_context = NULL; > > } > > + > > + /* Force the GPU state to be reinitialised on enabling */ > > + if (ring->default_context) > > + ring->default_context->legacy_hw_ctx.initialized = false; > > } > > } > > > > @@ -708,7 +712,7 @@ static int do_switch(struct drm_i915_gem_request *req) > > if (ret) > > goto unpin_out; > > > > - if (!to->legacy_hw_ctx.initialized) { > > + if (!to->legacy_hw_ctx.initialized || i915_gem_context_is_default(to)) { > > hw_flags |= MI_RESTORE_INHIBIT; > > /* NB: If we inhibit the restore, the context is not allowed to > > * die because future work may end up depending on valid address > > -- > > 2.6.2 > > > > _______________________________________________ > > Intel-gfx mailing list > > Intel-gfx@lists.freedesktop.org > > http://lists.freedesktop.org/mailman/listinfo/intel-gfx
Mika Kuoppala <mika.kuoppala@linux.intel.com> writes: > Chris Wilson <chris@chris-wilson.co.uk> writes: > >> Following a GPU reset, we may leave the context in a poorly defined >> state, and reloading from that context will leave the GPU flummoxed. For >> secondary contexts, this will lead to that context being banned - but >> currently it is also causing the default context to become banned, >> leading to turmoil in the shared state. >> >> This is a regression from >> >> commit 6702cf16e0ba8b0129f5aa1b6609d4e9c70bc13b [v4.1] >> Author: Ben Widawsky <benjamin.widawsky@intel.com> >> Date: Mon Mar 16 16:00:58 2015 +0000 >> >> drm/i915: Initialize all contexts >> >> which quietly introduced the removal of the MI_RESTORE_INHIBIT on the >> default context. >> AFAICT the removal of MI_RESTORE_INHIBIT in that commit seemed justified. Ben explained that it was needed to fix a pagefault in the default context under certain conditions. I don't know the details of the original change (Ben CC'ed), but it seems like this would be trading one bug for another? Other than that this opens the door again to subtle state leaks between processes, as I learned recently while implementing L3 partitioning in Mesa. Mesa now changes the L3 configuration in ways that will break assumptions from processes that use the default context (the DDX). The DDX assumes, for instance, that the URB size is set according to the hardware defaults, but it doesn't actually program the URB size itself, so in a way the DDX relies on MI_RESTORE_INHIBIT *not* to be set for the default context for correct operation. This commit breaks that assumption and the kernel ABI. Mesa has a workaround in place to reduce the likelihood of such leaks, but the solution is far from ideal because it relies on userspace cooperation and had a measurable impact in performance (because it requires userspace to assume the worst-case scenario that the following batch is going to be from a different context with MI_RESTORE_INHIBIT set, so we have to restore the hardware default L3 configuration at the end of every batch even if that's actually not the case), for that reason we would like to drop the userspace workaround in the future at least on v4.1 kernels and newer. One more question below. >> v2: Mark the global default context as uninitialized on GPU reset so >> that the context-local workarounds are reloaded upon re-enabling. >> >> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> > > Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com> > >> Cc: Michel Thierry <michel.thierry@intel.com> >> Cc: Mika Kuoppala <mika.kuoppala@intel.com> >> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> >> --- >> drivers/gpu/drm/i915/i915_gem_context.c | 6 +++++- >> 1 file changed, 5 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c >> index 43761c5bcaca..f024d5d2c746 100644 >> --- a/drivers/gpu/drm/i915/i915_gem_context.c >> +++ b/drivers/gpu/drm/i915/i915_gem_context.c >> @@ -340,6 +340,10 @@ void i915_gem_context_reset(struct drm_device *dev) >> i915_gem_context_unreference(lctx); >> ring->last_context = NULL; >> } >> + >> + /* Force the GPU state to be reinitialised on enabling */ >> + if (ring->default_context) >> + ring->default_context->legacy_hw_ctx.initialized = false; >> } >> } >> >> @@ -708,7 +712,7 @@ static int do_switch(struct drm_i915_gem_request *req) >> if (ret) >> goto unpin_out; >> >> - if (!to->legacy_hw_ctx.initialized) { >> + if (!to->legacy_hw_ctx.initialized || i915_gem_context_is_default(to)) { This hunk causes MI_RESTORE_INHIBIT to be set again for the default context regardless of whether a reset happened or not, so it seems unrelated to the rest of your change. Maybe I'm understanding this wrong but doesn't the !initialized check together with the hunk above already guarantee that MI_RESTORE_INHIBIT will be set after GPU reset, which is what you wanted to achieve? >> hw_flags |= MI_RESTORE_INHIBIT; >> /* NB: If we inhibit the restore, the context is not allowed to >> * die because future work may end up depending on valid address >> -- >> 2.6.2 >> >> _______________________________________________ >> Intel-gfx mailing list >> Intel-gfx@lists.freedesktop.org >> http://lists.freedesktop.org/mailman/listinfo/intel-gfx > _______________________________________________ > Intel-gfx mailing list > Intel-gfx@lists.freedesktop.org > http://lists.freedesktop.org/mailman/listinfo/intel-gfx
On Thu, Dec 10, 2015 at 03:24:52PM +0200, Francisco Jerez wrote: > Mika Kuoppala <mika.kuoppala@linux.intel.com> writes: > > > Chris Wilson <chris@chris-wilson.co.uk> writes: > > > >> Following a GPU reset, we may leave the context in a poorly defined > >> state, and reloading from that context will leave the GPU flummoxed. For > >> secondary contexts, this will lead to that context being banned - but > >> currently it is also causing the default context to become banned, > >> leading to turmoil in the shared state. > >> > >> This is a regression from > >> > >> commit 6702cf16e0ba8b0129f5aa1b6609d4e9c70bc13b [v4.1] > >> Author: Ben Widawsky <benjamin.widawsky@intel.com> > >> Date: Mon Mar 16 16:00:58 2015 +0000 > >> > >> drm/i915: Initialize all contexts > >> > >> which quietly introduced the removal of the MI_RESTORE_INHIBIT on the > >> default context. > >> > > AFAICT the removal of MI_RESTORE_INHIBIT in that commit seemed > justified. Ben explained that it was needed to fix a pagefault in the > default context under certain conditions. I don't know the details of > the original change (Ben CC'ed), but it seems like this would be trading > one bug for another? A bug in a feature that never worked and isn't enabled? > Other than that this opens the door again to subtle state leaks between > processes, as I learned recently while implementing L3 partitioning in > Mesa. Mesa now changes the L3 configuration in ways that will break > assumptions from processes that use the default context (the DDX). The > DDX assumes, for instance, that the URB size is set according to the > hardware defaults, but it doesn't actually program the URB size itself, > so in a way the DDX relies on MI_RESTORE_INHIBIT *not* to be set for the > default context for correct operation. This commit breaks that > assumption and the kernel ABI. Wrong the ABI is the other way around and has been for 10 years. Note the kernel isn't also ensuring that the default context has the default hardware values either. The "golden renderstate" also doesn't set all defaults and is also a recent introduction. It changes the ABI back to what it was.... > Mesa has a workaround in place to reduce the likelihood of such leaks, > but the solution is far from ideal because it relies on userspace > cooperation and had a measurable impact in performance (because it > requires userspace to assume the worst-case scenario that the following > batch is going to be from a different context with MI_RESTORE_INHIBIT > set, so we have to restore the hardware default L3 configuration at the > end of every batch even if that's actually not the case), for that > reason we would like to drop the userspace workaround in the future at > least on v4.1 kernels and newer. Mesa has workarounds for leaks between hardware contexts, i.e. state that is not stored in the context itself. Mesa also has to assume a clean slate when setting up the context for the first time, and doesn't use the default context itself. > One more question below. > > >> v2: Mark the global default context as uninitialized on GPU reset so > >> that the context-local workarounds are reloaded upon re-enabling. > >> > >> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> > > > > Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com> > > > >> Cc: Michel Thierry <michel.thierry@intel.com> > >> Cc: Mika Kuoppala <mika.kuoppala@intel.com> > >> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> > >> --- > >> drivers/gpu/drm/i915/i915_gem_context.c | 6 +++++- > >> 1 file changed, 5 insertions(+), 1 deletion(-) > >> > >> diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c > >> index 43761c5bcaca..f024d5d2c746 100644 > >> --- a/drivers/gpu/drm/i915/i915_gem_context.c > >> +++ b/drivers/gpu/drm/i915/i915_gem_context.c > >> @@ -340,6 +340,10 @@ void i915_gem_context_reset(struct drm_device *dev) > >> i915_gem_context_unreference(lctx); > >> ring->last_context = NULL; > >> } > >> + > >> + /* Force the GPU state to be reinitialised on enabling */ > >> + if (ring->default_context) > >> + ring->default_context->legacy_hw_ctx.initialized = false; > >> } > >> } > >> > >> @@ -708,7 +712,7 @@ static int do_switch(struct drm_i915_gem_request *req) > >> if (ret) > >> goto unpin_out; > >> > >> - if (!to->legacy_hw_ctx.initialized) { > >> + if (!to->legacy_hw_ctx.initialized || i915_gem_context_is_default(to)) { > > This hunk causes MI_RESTORE_INHIBIT to be set again for the default > context regardless of whether a reset happened or not, so it seems > unrelated to the rest of your change. Maybe I'm understanding this > wrong but doesn't the !initialized check together with the hunk above > already guarantee that MI_RESTORE_INHIBIT will be set after GPU reset, > which is what you wanted to achieve? This is the change to *restore* the kernel ABI. The flag in reset is to force the WA LRI to be re-emitted (not for gen6 ofc) as they will not be preserved. -Chris
Chris Wilson <chris@chris-wilson.co.uk> writes: > On Thu, Dec 10, 2015 at 03:24:52PM +0200, Francisco Jerez wrote: >> Mika Kuoppala <mika.kuoppala@linux.intel.com> writes: >> >> > Chris Wilson <chris@chris-wilson.co.uk> writes: >> > >> >> Following a GPU reset, we may leave the context in a poorly defined >> >> state, and reloading from that context will leave the GPU flummoxed. For >> >> secondary contexts, this will lead to that context being banned - but >> >> currently it is also causing the default context to become banned, >> >> leading to turmoil in the shared state. >> >> >> >> This is a regression from >> >> >> >> commit 6702cf16e0ba8b0129f5aa1b6609d4e9c70bc13b [v4.1] >> >> Author: Ben Widawsky <benjamin.widawsky@intel.com> >> >> Date: Mon Mar 16 16:00:58 2015 +0000 >> >> >> >> drm/i915: Initialize all contexts >> >> >> >> which quietly introduced the removal of the MI_RESTORE_INHIBIT on the >> >> default context. >> >> >> >> AFAICT the removal of MI_RESTORE_INHIBIT in that commit seemed >> justified. Ben explained that it was needed to fix a pagefault in the >> default context under certain conditions. I don't know the details of >> the original change (Ben CC'ed), but it seems like this would be trading >> one bug for another? > > A bug in a feature that never worked and isn't enabled? > >> Other than that this opens the door again to subtle state leaks between >> processes, as I learned recently while implementing L3 partitioning in >> Mesa. Mesa now changes the L3 configuration in ways that will break >> assumptions from processes that use the default context (the DDX). The >> DDX assumes, for instance, that the URB size is set according to the >> hardware defaults, but it doesn't actually program the URB size itself, >> so in a way the DDX relies on MI_RESTORE_INHIBIT *not* to be set for the >> default context for correct operation. This commit breaks that >> assumption and the kernel ABI. > > Wrong the ABI is the other way around and has been for 10 years. Note > the kernel isn't also ensuring that the default context has the default > hardware values either. The "golden renderstate" also doesn't set all > defaults and is also a recent introduction. > > It changes the ABI back to what it was.... Sounds like a change fully unrelated to fixing the bug on GPU reset. The ABI change done in 6702cf16e0ba8b0129f5aa1b6609d4e9c70bc13b seemed legitimate because it made the context state on switch more well-defined than it used to be, IOW it was a backwards-compatible ABI change because it couldn't possibly break userspace assumptions. This change OTOH breaks an assumption about the kernel ABI done by the DDX now. > >> Mesa has a workaround in place to reduce the likelihood of such leaks, >> but the solution is far from ideal because it relies on userspace >> cooperation and had a measurable impact in performance (because it >> requires userspace to assume the worst-case scenario that the following >> batch is going to be from a different context with MI_RESTORE_INHIBIT >> set, so we have to restore the hardware default L3 configuration at the >> end of every batch even if that's actually not the case), for that >> reason we would like to drop the userspace workaround in the future at >> least on v4.1 kernels and newer. > > Mesa has workarounds for leaks between hardware contexts, i.e. state > that is not stored in the context itself. Mesa also has to assume a > clean slate when setting up the context for the first time, and doesn't > use the default context itself. > No, the workaround involves restoring state which *is* part of the hardware context, it just won't get saved and restored with this commit because of the MI_RESTORE_INHIBIT flag when switching to the DDX' default context. >> One more question below. >> >> >> v2: Mark the global default context as uninitialized on GPU reset so >> >> that the context-local workarounds are reloaded upon re-enabling. >> >> >> >> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> >> > >> > Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com> >> > >> >> Cc: Michel Thierry <michel.thierry@intel.com> >> >> Cc: Mika Kuoppala <mika.kuoppala@intel.com> >> >> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> >> >> --- >> >> drivers/gpu/drm/i915/i915_gem_context.c | 6 +++++- >> >> 1 file changed, 5 insertions(+), 1 deletion(-) >> >> >> >> diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c >> >> index 43761c5bcaca..f024d5d2c746 100644 >> >> --- a/drivers/gpu/drm/i915/i915_gem_context.c >> >> +++ b/drivers/gpu/drm/i915/i915_gem_context.c >> >> @@ -340,6 +340,10 @@ void i915_gem_context_reset(struct drm_device *dev) >> >> i915_gem_context_unreference(lctx); >> >> ring->last_context = NULL; >> >> } >> >> + >> >> + /* Force the GPU state to be reinitialised on enabling */ >> >> + if (ring->default_context) >> >> + ring->default_context->legacy_hw_ctx.initialized = false; >> >> } >> >> } >> >> >> >> @@ -708,7 +712,7 @@ static int do_switch(struct drm_i915_gem_request *req) >> >> if (ret) >> >> goto unpin_out; >> >> >> >> - if (!to->legacy_hw_ctx.initialized) { >> >> + if (!to->legacy_hw_ctx.initialized || i915_gem_context_is_default(to)) { >> >> This hunk causes MI_RESTORE_INHIBIT to be set again for the default >> context regardless of whether a reset happened or not, so it seems >> unrelated to the rest of your change. Maybe I'm understanding this >> wrong but doesn't the !initialized check together with the hunk above >> already guarantee that MI_RESTORE_INHIBIT will be set after GPU reset, >> which is what you wanted to achieve? > > This is the change to *restore* the kernel ABI. The flag in reset is to > force the WA LRI to be re-emitted (not for gen6 ofc) as they will not be > preserved. Again you don't justify why changing the kernel ABI is required to fix a GPU reset bug. > -Chris > > -- > Chris Wilson, Intel Open Source Technology Centre
On Thu, Dec 10, 2015 at 01:37:56PM +0000, Chris Wilson wrote: > On Thu, Dec 10, 2015 at 03:24:52PM +0200, Francisco Jerez wrote: > > Mika Kuoppala <mika.kuoppala@linux.intel.com> writes: > > > > > Chris Wilson <chris@chris-wilson.co.uk> writes: > > > > > >> Following a GPU reset, we may leave the context in a poorly defined > > >> state, and reloading from that context will leave the GPU flummoxed. For > > >> secondary contexts, this will lead to that context being banned - but > > >> currently it is also causing the default context to become banned, > > >> leading to turmoil in the shared state. > > >> > > >> This is a regression from > > >> > > >> commit 6702cf16e0ba8b0129f5aa1b6609d4e9c70bc13b [v4.1] > > >> Author: Ben Widawsky <benjamin.widawsky@intel.com> > > >> Date: Mon Mar 16 16:00:58 2015 +0000 > > >> > > >> drm/i915: Initialize all contexts > > >> > > >> which quietly introduced the removal of the MI_RESTORE_INHIBIT on the > > >> default context. > > >> > > > > AFAICT the removal of MI_RESTORE_INHIBIT in that commit seemed > > justified. Ben explained that it was needed to fix a pagefault in the > > default context under certain conditions. I don't know the details of > > the original change (Ben CC'ed), but it seems like this would be trading > > one bug for another? > > A bug in a feature that never worked and isn't enabled? > > > Other than that this opens the door again to subtle state leaks between > > processes, as I learned recently while implementing L3 partitioning in > > Mesa. Mesa now changes the L3 configuration in ways that will break > > assumptions from processes that use the default context (the DDX). The > > DDX assumes, for instance, that the URB size is set according to the > > hardware defaults, but it doesn't actually program the URB size itself, > > so in a way the DDX relies on MI_RESTORE_INHIBIT *not* to be set for the > > default context for correct operation. This commit breaks that > > assumption and the kernel ABI. > > Wrong the ABI is the other way around and has been for 10 years. Note > the kernel isn't also ensuring that the default context has the default > hardware values either. The "golden renderstate" also doesn't set all > defaults and is also a recent introduction. > > It changes the ABI back to what it was.... Well it seems folks like the new ABI, even if somewhat accidental. And more isolation between clients can't hurt I think (well it does hurt perf somewhat). So I guess we need a respun patch that just makes sure that we restore the default context stuff after reset, probably by marking it as unitialized? And then just the one the kernel has I guess? -Daniel
On Thu, Dec 10, 2015 at 11:45:54AM +0100, Daniel Vetter wrote: > On Thu, Dec 10, 2015 at 12:19:29PM +0200, Mika Kuoppala wrote: > > Chris Wilson <chris@chris-wilson.co.uk> writes: > > > > > Following a GPU reset, we may leave the context in a poorly defined > > > state, and reloading from that context will leave the GPU flummoxed. For > > > secondary contexts, this will lead to that context being banned - but > > > currently it is also causing the default context to become banned, > > > leading to turmoil in the shared state. > > > > > > This is a regression from > > > > > > commit 6702cf16e0ba8b0129f5aa1b6609d4e9c70bc13b [v4.1] > > > Author: Ben Widawsky <benjamin.widawsky@intel.com> > > > Date: Mon Mar 16 16:00:58 2015 +0000 > > > > > > drm/i915: Initialize all contexts > > > > > > which quietly introduced the removal of the MI_RESTORE_INHIBIT on the > > > default context. > > > > > > v2: Mark the global default context as uninitialized on GPU reset so > > > that the context-local workarounds are reloaded upon re-enabling. > > > > > > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> > > > > Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com> > > Queued for -next, thanks for the patch. I guess I dropped this one again, but now merged again since it fixes a suspend/resume regression. -Daniel
diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c index 43761c5bcaca..f024d5d2c746 100644 --- a/drivers/gpu/drm/i915/i915_gem_context.c +++ b/drivers/gpu/drm/i915/i915_gem_context.c @@ -340,6 +340,10 @@ void i915_gem_context_reset(struct drm_device *dev) i915_gem_context_unreference(lctx); ring->last_context = NULL; } + + /* Force the GPU state to be reinitialised on enabling */ + if (ring->default_context) + ring->default_context->legacy_hw_ctx.initialized = false; } } @@ -708,7 +712,7 @@ static int do_switch(struct drm_i915_gem_request *req) if (ret) goto unpin_out; - if (!to->legacy_hw_ctx.initialized) { + if (!to->legacy_hw_ctx.initialized || i915_gem_context_is_default(to)) { hw_flags |= MI_RESTORE_INHIBIT; /* NB: If we inhibit the restore, the context is not allowed to * die because future work may end up depending on valid address
Following a GPU reset, we may leave the context in a poorly defined state, and reloading from that context will leave the GPU flummoxed. For secondary contexts, this will lead to that context being banned - but currently it is also causing the default context to become banned, leading to turmoil in the shared state. This is a regression from commit 6702cf16e0ba8b0129f5aa1b6609d4e9c70bc13b [v4.1] Author: Ben Widawsky <benjamin.widawsky@intel.com> Date: Mon Mar 16 16:00:58 2015 +0000 drm/i915: Initialize all contexts which quietly introduced the removal of the MI_RESTORE_INHIBIT on the default context. v2: Mark the global default context as uninitialized on GPU reset so that the context-local workarounds are reloaded upon re-enabling. Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Michel Thierry <michel.thierry@intel.com> Cc: Mika Kuoppala <mika.kuoppala@intel.com> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> --- drivers/gpu/drm/i915/i915_gem_context.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)