From 33136b06d54915680c36f4cd89dadef068b88974 Mon Sep 17 00:00:00 2001 From: Arun Siluvery Date: Thu, 21 Jan 2016 21:43:47 +0000 Subject: [PATCH] drm/i915/gen9: Add framework to whitelist specific GPU registers Some of the HW registers are privileged and cannot be written to from non-privileged batch buffers coming from userspace unless they are added to the HW whitelist. This whitelist is maintained by HW and it is different from SW whitelist. Userspace need write access to them to implement preemption related WA. The reason for using this approach is, the register bits that control preemption granularity at the HW level are not context save/restored; so even if we set these bits always in kernel they are going to change once the context is switched out. We can consider making them non-privileged by default but these registers also contain other chicken bits which should not be allowed to be modified. In the later revisions controlling bits are save/restored at context level but in the existing revisions these are exported via other debug registers and should be on the whitelist. This patch adds changes to provide HW with a list of registers to be whitelisted. HW checks this list during execution and provides access accordingly. HW imposes a limit on the number of registers on whitelist and it is per-engine. At this point we are only enabling whitelist for RCS and we don't foresee any requirement for other engines. The registers to be whitelisted are added using generic workaround list mechanism, even these are only enablers for userspace workarounds. But by sharing this mechanism we get some test assets without additional cost (Mika). v2: rebase v3: parameterize RING_FORCE_TO_NONPRIV() as _MMIO() should be limited to i915_reg.h (Ville), drop inline for wa_ring_whitelist_reg (Mika). v4: improvements suggested by Chris Wilson. Clarify that this is HW whitelist and different from the one maintained in driver. This list is engine specific but it gets initialized along with other WA which is RCS specific thing, so make it clear that we are not doing any cross engine setup during initialization. Make HW whitelist count of each engine available in debugfs. Reviewed-by: Chris Wilson Reviewed-by: Mika Kuoppala Cc: Mika Kuoppala Cc: Chris Wilson Signed-off-by: Arun Siluvery Link: http://patchwork.freedesktop.org/patch/msgid/1453412634-29238-2-git-send-email-arun.siluvery@linux.intel.com Signed-off-by: Daniel Vetter --- drivers/gpu/drm/i915/i915_debugfs.c | 15 ++++++++++----- drivers/gpu/drm/i915/i915_drv.h | 9 ++++++++- drivers/gpu/drm/i915/i915_reg.h | 3 +++ drivers/gpu/drm/i915/intel_ringbuffer.c | 17 +++++++++++++++++ 4 files changed, 38 insertions(+), 6 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c index cea184459256..863012a2602e 100644 --- a/drivers/gpu/drm/i915/i915_debugfs.c +++ b/drivers/gpu/drm/i915/i915_debugfs.c @@ -3221,9 +3221,11 @@ static int i915_wa_registers(struct seq_file *m, void *unused) { int i; int ret; + struct intel_engine_cs *ring; struct drm_info_node *node = (struct drm_info_node *) m->private; struct drm_device *dev = node->minor->dev; struct drm_i915_private *dev_priv = dev->dev_private; + struct i915_workarounds *workarounds = &dev_priv->workarounds; ret = mutex_lock_interruptible(&dev->struct_mutex); if (ret) @@ -3231,15 +3233,18 @@ static int i915_wa_registers(struct seq_file *m, void *unused) intel_runtime_pm_get(dev_priv); - seq_printf(m, "Workarounds applied: %d\n", dev_priv->workarounds.count); - for (i = 0; i < dev_priv->workarounds.count; ++i) { + seq_printf(m, "Workarounds applied: %d\n", workarounds->count); + for_each_ring(ring, dev_priv, i) + seq_printf(m, "HW whitelist count for %s: %d\n", + ring->name, workarounds->hw_whitelist_count[i]); + for (i = 0; i < workarounds->count; ++i) { i915_reg_t addr; u32 mask, value, read; bool ok; - addr = dev_priv->workarounds.reg[i].addr; - mask = dev_priv->workarounds.reg[i].mask; - value = dev_priv->workarounds.reg[i].value; + addr = workarounds->reg[i].addr; + mask = workarounds->reg[i].mask; + value = workarounds->reg[i].value; read = I915_READ(addr); ok = (value & mask) == (read & mask); seq_printf(m, "0x%X: 0x%08X, mask: 0x%08X, read: 0x%08x, status: %s\n", diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h index afb0beee9975..211af534e5d0 100644 --- a/drivers/gpu/drm/i915/i915_drv.h +++ b/drivers/gpu/drm/i915/i915_drv.h @@ -1657,11 +1657,18 @@ struct i915_wa_reg { u32 mask; }; -#define I915_MAX_WA_REGS 16 +/* + * RING_MAX_NONPRIV_SLOTS is per-engine but at this point we are only + * allowing it for RCS as we don't foresee any requirement of having + * a whitelist for other engines. When it is really required for + * other engines then the limit need to be increased. + */ +#define I915_MAX_WA_REGS (16 + RING_MAX_NONPRIV_SLOTS) struct i915_workarounds { struct i915_wa_reg reg[I915_MAX_WA_REGS]; u32 count; + u32 hw_whitelist_count[I915_NUM_RINGS]; }; struct i915_virtual_gpu { diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h index 0a988895165f..79388147184c 100644 --- a/drivers/gpu/drm/i915/i915_reg.h +++ b/drivers/gpu/drm/i915/i915_reg.h @@ -1635,6 +1635,9 @@ enum skl_disp_power_wells { #define RING_WAIT (1<<11) /* gen3+, PRBx_CTL */ #define RING_WAIT_SEMAPHORE (1<<10) /* gen6+ */ +#define RING_FORCE_TO_NONPRIV(base, i) _MMIO(((base)+0x4D0) + (i)*4) +#define RING_MAX_NONPRIV_SLOTS 12 + #define GEN7_TLB_RD_ADDR _MMIO(0x4700) #if 0 diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c index 9030e2bca0c0..43fa1403159e 100644 --- a/drivers/gpu/drm/i915/intel_ringbuffer.c +++ b/drivers/gpu/drm/i915/intel_ringbuffer.c @@ -789,6 +789,22 @@ static int wa_add(struct drm_i915_private *dev_priv, #define WA_WRITE(addr, val) WA_REG(addr, 0xffffffff, val) +static int wa_ring_whitelist_reg(struct intel_engine_cs *ring, i915_reg_t reg) +{ + struct drm_i915_private *dev_priv = ring->dev->dev_private; + struct i915_workarounds *wa = &dev_priv->workarounds; + const uint32_t index = wa->hw_whitelist_count[ring->id]; + + if (WARN_ON(index >= RING_MAX_NONPRIV_SLOTS)) + return -EINVAL; + + WA_WRITE(RING_FORCE_TO_NONPRIV(ring->mmio_base, index), + i915_mmio_reg_offset(reg)); + wa->hw_whitelist_count[ring->id]++; + + return 0; +} + static int gen8_init_workarounds(struct intel_engine_cs *ring) { struct drm_device *dev = ring->dev; @@ -1117,6 +1133,7 @@ int init_workarounds_ring(struct intel_engine_cs *ring) WARN_ON(ring->id != RCS); dev_priv->workarounds.count = 0; + dev_priv->workarounds.hw_whitelist_count[RCS] = 0; if (IS_BROADWELL(dev)) return bdw_init_workarounds(ring); -- 2.30.2