benchmarks/gem_wsim: add explicit VM create/assign steps

Add explicit VM (Virtual Memory) management to workload descriptors so Xe
runs can model VM topology directly.

Introduce two new descriptor steps:
- V.N     create VM id N (1-based)
- v.N.M   assign VM N to context M

Implementation details:
- Add VM_CREATE and CTX_VM step types and vm_id storage in w_step.
- Parse V/v syntax with validation and clear error messages.
- Add allocate_vms() pre-scan to size and allocate vm_list from V steps.
- Update xe_prepare_contexts() to support explicit VM mode:
  - create all explicit VMs
  - default contexts to VM 0
  - apply per-context VM assignments from v steps
  - retain implicit single-VM fallback when no V steps are present
- Make get_vm() use per-context VM linkage.

Documentation:
- Add VM (Virtual Memory) management step documentation into
  benchmarks/wsim/README.

This keeps i915 behavior unchanged while enabling explicit VM topology
control for Xe workloads.

Suggested-by: Tvrtko Ursulin <tvrtko.ursulin@igalia.com>
Signed-off-by: Marcin Bernatowicz <marcin.bernatowicz@linux.intel.com>
Cc: Adam Miszczak <adam.miszczak@linux.intel.com>
Cc: Lukasz Laguna <lukasz.laguna@intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@igalia.com>
Reviewed-by: Adam Miszczak <adam.miszczak@linux.intel.com>

1 files changed, 19 insertions, 0 deletions

diff --git a/benchmarks/wsim/README b/benchmarks/wsim/README
index e43813335..364759da0 100644
--- a/benchmarks/wsim/README
+++ b/benchmarks/wsim/README
@@ -11,6 +11,8 @@ P|S|X.<uint>.<int>
 d|p|s|t|q|a|T.<int>,...
 b.<uint>.<str>[|<str>].<str>
 w|W.<uint>.<str>[/<str>]...
+V.<uint>
+v.<uint>.<uint>
 f
 
 For duration a range can be given from which a random value will be picked
@@ -39,6 +41,11 @@ Additional workload steps are also supported:
  'W' - Shared working set.
  'X' - Context preemption control.
 
+VM (Virtual Memory) management steps (Xe: active; i915: ignored):
+
+ 'V' - Create VM with id N (V.N, VM ids are 1-based).
+ 'v' - Assign VM N to context/queue M (v.N.M).
+
 Engine ids: DEFAULT, RCS, BCS, VCS, VCS1, VCS2, VECS
 
 Example (leading spaces must not be present in the actual file):
@@ -88,6 +95,18 @@ Batch durations can also be specified as infinite by using the '*' in the
 duration field. Such batches must be ended by the terminate command ('T')
 otherwise they will cause a GPU hang to be reported.
 
+VM Example:
+
+  V.1
+  M.1.VCS
+  v.1.1
+  B.1
+  1.VCS.1000.0.0
+
+Creates VM 1, configures context 1 with a VCS engine map, assigns context 1
+to VM 1, enables load balancing for context 1, and runs a single 1ms VCS
+batch.
+
 Xe and i915 differences
 ------------------------