On 17/03/2017 09:42, Xu, Terrence wrote:
-----Original Message-----
From: Tvrtko Ursulin [mailto:tvrtko.ursulin@xxxxxxxxxxxxxxx]
Sent: Friday, March 17, 2017 5:30 PM
To: Zhenyu Wang <zhenyuw@xxxxxxxxxxxxxxx>
Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>; Tvrtko Ursulin
<tursulin@xxxxxxxxxxx>; Intel-gfx@xxxxxxxxxxxxxxxxxxxxx; Ursulin, Tvrtko
<tvrtko.ursulin@xxxxxxxxx>; Li, Weinan Z <weinan.z.li@xxxxxxxxx>; Xu,
Terrence <terrence.xu@xxxxxxxxx>
Subject: Re: [PATCH] drm/i915/vgpu: Neuter forcewakes for VGPU
more thouroughly
Hi,
On 13/03/2017 09:37, Zhenyu Wang wrote:
On 2017.03.13 09:26:26 +0000, Tvrtko Ursulin wrote:
On 10/03/2017 10:09, Chris Wilson wrote:
On Fri, Mar 10, 2017 at 09:57:47AM +0000, Tvrtko Ursulin wrote:
From: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
If we avoid initializing forcewake domains when running as a guest,
and also use gen2 mmio accessors in that case, we can avoid the
timer traffic and any looping through the forcewake code which is
currently just so it can end up in the no-op forcewake
implementation.
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
Cc: Weinan Li <weinan.z.li@xxxxxxxxx>
Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/intel_uncore.c | 76
+++++++++++++------------------------
1 file changed, 27 insertions(+), 49 deletions(-)
diff --git a/drivers/gpu/drm/i915/intel_uncore.c
b/drivers/gpu/drm/i915/intel_uncore.c
index 71b9b387ad04..09f5f02d7901 100644
--- a/drivers/gpu/drm/i915/intel_uncore.c
+++ b/drivers/gpu/drm/i915/intel_uncore.c
@@ -138,13 +138,6 @@ fw_domains_put(struct drm_i915_private
*dev_priv, enum forcewake_domains fw_doma }
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; @@ -1187,7 +1180,7
@@
static void fw_domain_init(struct drm_i915_private *dev_priv,
static void intel_uncore_fw_domains_init(struct drm_i915_private
*dev_priv) {
- if (INTEL_INFO(dev_priv)->gen <= 5)
+ if (INTEL_GEN(dev_priv) <= 5 || intel_vgpu_active(dev_priv))
Make these separate ifs, they aren't semantically related so be verbose.
return;
if (IS_GEN9(dev_priv)) {
@@ -1273,11 +1266,6 @@ static void
intel_uncore_fw_domains_init(struct drm_i915_private *dev_priv)
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); } @@ -1327,22
+1315,22 @@ void intel_uncore_init(struct drm_i915_private
*dev_priv)
dev_priv->uncore.pmic_bus_access_nb.notifier_call =
i915_pmic_bus_access_notifier;
- switch (INTEL_INFO(dev_priv)->gen) {
- default:
- case 9:
- ASSIGN_FW_DOMAINS_TABLE(__gen9_fw_ranges);
- ASSIGN_WRITE_MMIO_VFUNCS(fwtable);
- ASSIGN_READ_MMIO_VFUNCS(fwtable);
- if (HAS_DECOUPLED_MMIO(dev_priv)) {
- dev_priv->uncore.funcs.mmio_readl =
- gen9_decoupled_read32;
- dev_priv->uncore.funcs.mmio_readq =
- gen9_decoupled_read64;
- dev_priv->uncore.funcs.mmio_writel =
- gen9_decoupled_write32;
+ if (IS_GEN(dev_priv, 2, 4) || intel_vgpu_active(dev_priv)) {
Ok, this doesn't look too bad.
Do the gvt-g hosts in CI now provide coverage for us of vgpu paths?
No idea.
Adding Zhenyu. So this patch avoids burning CPU cycles in guests and
scheduling timers when all of that ends up in the dummy/no-op
forcewake implementation.
If interesting to you, would it be easy for you to test it or how
should we proceed?
Patch looks fine to me. I can apply it for our QA testing if required.
Were you perhaps able to smoke test this one?
Hi Ursulin, we have verified your patch in guest, no regression be found.
Tested-by: Terrence Xu <terrence.xu@xxxxxxxxx>
Thanks!
Regards,
Tvrtko
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