linux-kernel - Re: refactor the i915 GVT support

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Date:   Thu, 19 Aug 2021 16:29:29 +0800
From:   Zhenyu Wang <zhenyuw@...ux.intel.com>
To:     Christoph Hellwig <hch@....de>
Cc:     Jason Gunthorpe <jgg@...dia.com>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        Greg KH <gregkh@...uxfoundation.org>,
        "intel-gfx@...ts.freedesktop.org" <intel-gfx@...ts.freedesktop.org>,
        Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Jani Nikula <jani.nikula@...ux.intel.com>,
        Gerd Hoffmann <kraxel@...hat.com>,
        "Vivi, Rodrigo" <rodrigo.vivi@...el.com>,
        "intel-gvt-dev@...ts.freedesktop.org" 
        <intel-gvt-dev@...ts.freedesktop.org>,
        "Wang, Zhi A" <zhi.a.wang@...el.com>,
        Jani Nikula <jani.nikula@...el.com>
Subject: Re: refactor the i915 GVT support

On 2021.08.17 13:22:03 +0800, Zhenyu Wang wrote:
> > On 2021.08.16 19:34:58 +0200, Christoph Hellwig wrote:
> > > Any updates on this?  I'd really hate to miss this merge window.
> > 
> > I'm still waiting for our validation team's report on this. I'm afraid
> > it might be missing for next version as i915 merge window is mostly
> > till rc5...and for any change outside of gvt, it still needs to be
> > acked by i915 maintainers.
> 
> Looks our validation team did have problem against recent i915 change.
> If you like to try, we have a gvt-staging branch on
> https://github.com/intel/gvt-linux which is generated against drm-tip
> with gvt changes for testing, currently it's broken.
> 
> One issue is with i915 export that intel_context_unpin has been
> changed into static inline function. Another is that intel_gvt.c
> should be part of i915 for gvt interface instead of depending on KVMGT
> config.

I'm working on below patch to resolve this. But I met a weird issue in
case when building i915 as module and also kvmgt module, it caused
busy wait on request_module("kvmgt") when boot, it doesn't happen if
building i915 into kernel. I'm not sure what could be the reason?

> But the problem I see is that after moving gvt device model (gvt/*.c
> except kvmgt.c) into kvmgt module, we'll have issue with initial mmio
> state which current gvt relies on, that is in design supposed to get
> initial HW state before i915 driver has taken any operation.  Before
> we can ensure that, I think we may only remove MPT part first but
> still keep gvt device model as part of i915 with config. I'll try to
> split that out.

Sorry I misread the code that as we always request kvmgt module when
gvt init, so it should still apply original method that this isn't a
problem. Our current validation result has shown no regression as well.

---8<---
From 58ff84572f1a0f9d79ca1d7ec0cff5ecbe78d280 Mon Sep 17 00:00:00 2001
From: Zhenyu Wang <zhenyuw@...ux.intel.com>
Date: Thu, 19 Aug 2021 16:36:33 +0800
Subject: [PATCH] TESTONLY:drm/i915/gvt: potential fix for refactor against
 current tip

---
 drivers/gpu/drm/i915/Makefile           | 4 +++-
 drivers/gpu/drm/i915/gt/intel_context.c | 5 +++++
 drivers/gpu/drm/i915/gt/intel_context.h | 3 ++-
 drivers/gpu/drm/i915/i915_trace.h       | 1 +
 4 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
index c4f953837f72..2248574428a1 100644
--- a/drivers/gpu/drm/i915/Makefile
+++ b/drivers/gpu/drm/i915/Makefile
@@ -296,7 +296,9 @@ i915-$(CONFIG_DRM_I915_SELFTEST) += \
 
 # virtual gpu code
 i915-y += i915_vgpu.o
-i915-$(CONFIG_DRM_I915_GVT_KVMGT) += intel_gvt.o
+ifneq ($(CONFIG_DRM_I915_GVT_KVMGT),)
+i915-y += intel_gvt.o
+endif
 
 kvmgt-y += gvt/kvmgt.o \
 	gvt/gvt.o \
diff --git a/drivers/gpu/drm/i915/gt/intel_context.c b/drivers/gpu/drm/i915/gt/intel_context.c
index 745e84c72c90..20e7522fed84 100644
--- a/drivers/gpu/drm/i915/gt/intel_context.c
+++ b/drivers/gpu/drm/i915/gt/intel_context.c
@@ -328,6 +328,11 @@ void __intel_context_do_unpin(struct intel_context *ce, int sub)
 	intel_context_put(ce);
 }
 
+void intel_context_unpin(struct intel_context *ce)
+{
+	_intel_context_unpin(ce);
+}
+
 static void __intel_context_retire(struct i915_active *active)
 {
 	struct intel_context *ce = container_of(active, typeof(*ce), active);
diff --git a/drivers/gpu/drm/i915/gt/intel_context.h b/drivers/gpu/drm/i915/gt/intel_context.h
index c41098950746..f942cbf6300a 100644
--- a/drivers/gpu/drm/i915/gt/intel_context.h
+++ b/drivers/gpu/drm/i915/gt/intel_context.h
@@ -131,7 +131,7 @@ static inline void intel_context_sched_disable_unpin(struct intel_context *ce)
 	__intel_context_do_unpin(ce, 2);
 }
 
-static inline void intel_context_unpin(struct intel_context *ce)
+static inline void _intel_context_unpin(struct intel_context *ce)
 {
 	if (!ce->ops->sched_disable) {
 		__intel_context_do_unpin(ce, 1);
@@ -150,6 +150,7 @@ static inline void intel_context_unpin(struct intel_context *ce)
 		}
 	}
 }
+void intel_context_unpin(struct intel_context *ce);
 
 void intel_context_enter_engine(struct intel_context *ce);
 void intel_context_exit_engine(struct intel_context *ce);
diff --git a/drivers/gpu/drm/i915/i915_trace.h b/drivers/gpu/drm/i915/i915_trace.h
index 806ad688274b..2c6a8bcef7c1 100644
--- a/drivers/gpu/drm/i915/i915_trace.h
+++ b/drivers/gpu/drm/i915/i915_trace.h
@@ -17,6 +17,7 @@
 
 #undef TRACE_SYSTEM
 #define TRACE_SYSTEM i915
+#undef TRACE_INCLUDE_FILE
 #define TRACE_INCLUDE_FILE i915_trace
 
 /* watermark/fifo updates */
-- 
2.32.0
---8<---



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