Yan Zhao fb55c73552 drm/i915/gvt: skip populate shadow context if guest context not changed
Software is not expected to populate engine context except when using
restore inhibit bit or golden state to initialize it for the first time.

Therefore, if a newly submitted guest context is the same as the last
shadowed one, no need to populate its engine context from guest again.

Currently using lrca + ring_context_gpa to identify whether two guest
contexts are the same.

The reason of why context id is not included as an identifier is that
i915 recently changed the code and context id is only unique for a
context when OA is enabled. And when OA is on, context id is generated
based on lrca. Therefore, in that case, if two contexts are of the same
lrca, they have identical context ids as well.
(This patch also works with old guest kernel like 4.20.)

for guest context, if its ggtt entry is modified after last context
shadowing, it is also deemed as not the same context as last shadowed one.

v7:
-removed local variable "valid". use the one in s->last_ctx diretly

v6:
-change type of lrca of last ctx to be u32. as currently it's all
protected by vgpu lock (Kevin Tian)
-reset valid of last ctx to false once it needs to be repopulated before
population completes successfully (Kevin Tian)

v5:
-merge all 3 patches into one patch  (Zhenyu Wang)

v4:
- split the series into 3 patches.
- don't turn on optimization until last patch in this series (Kevin Tian)
- define lrca to be atomic in this patch rather than update its type in
the second patch (Kevin Tian)

v3: updated commit message to describe engine context and context id
clearly (Kevin Tian)
v2: rebased to 5.6.0-rc4+Signed-off-by: Yan Zhao <yan.y.zhao@intel.com>

Reviewed-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Cc: Kevin Tian <kevin.tian@intel.com>
Suggested-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Signed-off-by: Yan Zhao <yan.y.zhao@intel.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20200417091334.32628-1-yan.y.zhao@intel.com
2020-04-17 17:31:22 +08:00
2020-01-20 11:42:57 +10:00
2019-12-09 10:36:44 -08:00
2020-01-20 11:42:57 +10:00
2020-01-20 11:42:57 +10:00
2020-01-11 14:33:39 -08:00
2019-10-29 04:43:29 -06:00
2020-01-19 16:02:49 -08:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.
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