Host maintian the hardware's forcewake state, guest don't need and also
can't control it. Although vgpu_read/write bypass forcewake_get/put in MMIO
read/write, but still have separate path called by
"intel_uncore_forcewake_get/put" and
"intel_uncore_forcewake_get/put__locked". Unnecessary MMIO access in guest
waste much CPU cost. Since we full virtualize the MMIO, just noop the
forcewake get/put.
Signed-off-by: Weinan Li <weinan.z.li@xxxxxxxxx>
---
drivers/gpu/drm/i915/intel_uncore.c | 13 +++++++++++++
1 file changed, 13 insertions(+)
diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c
index abe0888..9fad4de 100644
--- a/drivers/gpu/drm/i915/intel_uncore.c
+++ b/drivers/gpu/drm/i915/intel_uncore.c
@@ -133,6 +133,13 @@
}
static void
+vgpu_fw_domains_nop(struct drm_i915_private *dev_priv,
+ enum forcewake_domains fw_domains)
+{
+ /* Guest driver doesn't need to takes care forcewake. */
+}
+
+static void
fw_domains_posting_read(struct drm_i915_private *dev_priv)
{
struct intel_uncore_forcewake_domain *d;
@@ -1374,6 +1381,12 @@ static void intel_uncore_fw_domains_init(struct drm_i915_private *dev_priv)
fw_domain_init(dev_priv, FW_DOMAIN_ID_RENDER,
FORCEWAKE, FORCEWAKE_ACK);
}
+ if (intel_vgpu_active(dev_priv)) {
+ dev_priv->uncore.funcs.force_wake_get =
+ vgpu_fw_domains_nop;
+ dev_priv->uncore.funcs.force_wake_put =
+ vgpu_fw_domains_nop;
+ }
/* All future platforms are expected to require complex power gating */
WARN_ON(dev_priv->uncore.fw_domains == 0);
--
1.9.1
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