[PATCH 2/2] drm/i915: ignore forcewake get/put when using vgpu
Li, Weinan Z
weinan.z.li at intel.com
Wed Jan 25 02:37:08 UTC 2017
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".
The original problem comes from 4.4 kenel guest, it will access forcewake_get/put frequently when have heavy workload, unnecessary MMIO access in guest waste much CPU cost.
So if we full virtualize the MMIO, shall we ignore the forcewake get/put in low level.
Thanks.
Best Regards.
Weinan, LI
> -----Original Message-----
> From: Zhenyu Wang [mailto:zhenyuw at linux.intel.com]
> Sent: Wednesday, January 25, 2017 9:57 AM
> To: Tian, Kevin <kevin.tian at intel.com>
> Cc: Li, Weinan Z <weinan.z.li at intel.com>; intel-gvt-
> dev at lists.freedesktop.org
> Subject: Re: [PATCH 2/2] drm/i915: ignore forcewake get/put when using
> vgpu
>
> On 2017.01.23 01:42:48 +0000, Tian, Kevin wrote:
> > does it make sense to make below configurable?
> >
>
> VGPU_READ/WRITE is supposed to ignore forcewake setting for guest right?
> Although this change can also do that, what's the real point of this?
>
> And anyway for any i915 change, need to send to intel-gfx and cc gvt.
>
> > > Subject: [PATCH 2/2] drm/i915: ignore forcewake get/put when using
> > > vgpu
> > >
> > > Host maintian the hardware's forcewake state, guest don't need and
> > > also can't control it, just ignore. Remove vgpu_read/write.
> > >
> > > Signed-off-by: Weinan Li <weinan.z.li at intel.com>
> > > ---
> > > drivers/gpu/drm/i915/intel_uncore.c | 78
> > > ++++++++++---------------------------
> > > 1 file changed, 20 insertions(+), 58 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/i915/intel_uncore.c
> > > b/drivers/gpu/drm/i915/intel_uncore.c
> > > index abe0888..08e1b5f 100644
> > > --- a/drivers/gpu/drm/i915/intel_uncore.c
> > > +++ b/drivers/gpu/drm/i915/intel_uncore.c
> > > @@ -133,6 +133,20 @@
> > > }
> > >
> > > static void
> > > +vgpu_fw_domains_get(struct drm_i915_private *dev_priv,
> > > + enum forcewake_domains fw_domains) {
> > > + /* Guest driver doesn't need to takes care forcewake. */; }
> > > +
> > > +static void
> > > +vgpu_fw_domains_put(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; @@ -1045,34 +1059,6
> @@
> > > static inline void __force_wake_auto(struct drm_i915_private
> > > *dev_priv, #undef GEN6_READ_FOOTER #undef GEN6_READ_HEADER
> > >
> > > -#define VGPU_READ_HEADER(x) \
> > > - unsigned long irqflags; \
> > > - u##x val = 0; \
> > > - assert_rpm_device_not_suspended(dev_priv); \
> > > - spin_lock_irqsave(&dev_priv->uncore.lock, irqflags)
> > > -
> > > -#define VGPU_READ_FOOTER \
> > > - spin_unlock_irqrestore(&dev_priv->uncore.lock, irqflags); \
> > > - trace_i915_reg_rw(false, reg, val, sizeof(val), trace); \
> > > - return val
> > > -
> > > -#define __vgpu_read(x) \
> > > -static u##x \
> > > -vgpu_read##x(struct drm_i915_private *dev_priv, i915_reg_t reg, bool
> trace) { \
> > > - VGPU_READ_HEADER(x); \
> > > - val = __raw_i915_read##x(dev_priv, reg); \
> > > - VGPU_READ_FOOTER; \
> > > -}
> > > -
> > > -__vgpu_read(8)
> > > -__vgpu_read(16)
> > > -__vgpu_read(32)
> > > -__vgpu_read(64)
> > > -
> > > -#undef __vgpu_read
> > > -#undef VGPU_READ_FOOTER
> > > -#undef VGPU_READ_HEADER
> > > -
> > > #define GEN2_WRITE_HEADER \
> > > trace_i915_reg_rw(true, reg, val, sizeof(val), trace); \
> > > assert_rpm_wakelock_held(dev_priv); \ @@ -1195,31 +1181,6 @@
> > > static inline void __force_wake_auto(struct drm_i915_private
> > > *dev_priv, #undef GEN6_WRITE_FOOTER #undef
> GEN6_WRITE_HEADER
> > >
> > > -#define VGPU_WRITE_HEADER \
> > > - unsigned long irqflags; \
> > > - trace_i915_reg_rw(true, reg, val, sizeof(val), trace); \
> > > - assert_rpm_device_not_suspended(dev_priv); \
> > > - spin_lock_irqsave(&dev_priv->uncore.lock, irqflags)
> > > -
> > > -#define VGPU_WRITE_FOOTER \
> > > - spin_unlock_irqrestore(&dev_priv->uncore.lock, irqflags)
> > > -
> > > -#define __vgpu_write(x) \
> > > -static void vgpu_write##x(struct drm_i915_private *dev_priv, \
> > > - i915_reg_t reg, u##x val, bool trace) { \
> > > - VGPU_WRITE_HEADER; \
> > > - __raw_i915_write##x(dev_priv, reg, val); \
> > > - VGPU_WRITE_FOOTER; \
> > > -}
> > > -
> > > -__vgpu_write(8)
> > > -__vgpu_write(16)
> > > -__vgpu_write(32)
> > > -
> > > -#undef __vgpu_write
> > > -#undef VGPU_WRITE_FOOTER
> > > -#undef VGPU_WRITE_HEADER
> > > -
> > > #define ASSIGN_WRITE_MMIO_VFUNCS(x) \ do { \
> > > dev_priv->uncore.funcs.mmio_writeb = x##_write8; \ @@ -1375,6
> > > +1336,12 @@ 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_get;
> > > + dev_priv->uncore.funcs.force_wake_put =
> > > + vgpu_fw_domains_put;
> > > + }
> > > /* All future platforms are expected to require complex power gating
> */
> > > WARN_ON(dev_priv->uncore.fw_domains == 0); } @@ -1449,11
> +1416,6
> > > @@ void intel_uncore_init(struct drm_i915_private *dev_priv)
> > > if (INTEL_GEN(dev_priv) >= 8)
> > > intel_shadow_table_check();
> > >
> > > - if (intel_vgpu_active(dev_priv)) {
> > > - ASSIGN_WRITE_MMIO_VFUNCS(vgpu);
> > > - ASSIGN_READ_MMIO_VFUNCS(vgpu);
> > > - }
> > > -
> > > i915_check_and_clear_faults(dev_priv);
> > > }
> > > #undef ASSIGN_WRITE_MMIO_VFUNCS
> > > --
> > > 1.9.1
> > >
> > > _______________________________________________
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