From 331f38e77d4519d2ca60cea232c7f2bfad5e4d28 Mon Sep 17 00:00:00 2001 From: Zhiyuan Lv Date: Fri, 28 Aug 2015 15:41:14 +0800 Subject: [PATCH] drm/i915: preallocate pdps for 32 bit vgpu This is based on Mika Kuoppala's patch below: http://article.gmane.org/gmane.comp.freedesktop.xorg.drivers.intel/61104/match=workaround+hw+preload The patch will preallocate the page directories for 32-bit PPGTT when i915 runs inside a virtual machine with Intel GVT-g. With this change, the root pointers in EXECLIST context will always keep the same. The change is needed for vGPU because Intel GVT-g will do page table shadowing, and needs to track all the page table changes from guest i915 driver. However, if guest PPGTT is modified through GPU commands like LRI, it is not possible to trap the operations in the right time, so it will be hard to make shadow PPGTT to work correctly. Shadow PPGTT could be much simpler with this change. Meanwhile hypervisor could simply prohibit any attempt of PPGTT modification through GPU command for security. The function gen8_preallocate_top_level_pdps() in the patch is from Mika, with only one change to set "used_pdpes" to avoid duplicated allocation later. Cc: Mika Kuoppala Cc: Dave Gordon Cc: Michel Thierry Signed-off-by: Zhiyuan Lv Signed-off-by: Zhi Wang Reviewed-by: Joonas Lahtinen Signed-off-by: Daniel Vetter --- drivers/gpu/drm/i915/i915_gem_gtt.c | 33 +++++++++++++++++++++++++++++++++ drivers/gpu/drm/i915/intel_lrc.c | 3 ++- 2 files changed, 35 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c index 4a768071..ed10e77 100644 --- a/drivers/gpu/drm/i915/i915_gem_gtt.c +++ b/drivers/gpu/drm/i915/i915_gem_gtt.c @@ -1441,6 +1441,33 @@ static void gen8_dump_ppgtt(struct i915_hw_ppgtt *ppgtt, struct seq_file *m) } } +static int gen8_preallocate_top_level_pdps(struct i915_hw_ppgtt *ppgtt) +{ + unsigned long *new_page_dirs, **new_page_tables; + uint32_t pdpes = I915_PDPES_PER_PDP(dev); + int ret; + + /* We allocate temp bitmap for page tables for no gain + * but as this is for init only, lets keep the things simple + */ + ret = alloc_gen8_temp_bitmaps(&new_page_dirs, &new_page_tables, pdpes); + if (ret) + return ret; + + /* Allocate for all pdps regardless of how the ppgtt + * was defined. + */ + ret = gen8_ppgtt_alloc_page_directories(&ppgtt->base, &ppgtt->pdp, + 0, 1ULL << 32, + new_page_dirs); + if (!ret) + *ppgtt->pdp.used_pdpes = *new_page_dirs; + + free_gen8_temp_bitmaps(new_page_dirs, new_page_tables, pdpes); + + return ret; +} + /* * GEN8 legacy ppgtt programming is accomplished through a max 4 PDP registers * with a net effect resembling a 2-level page table in normal x86 terms. Each @@ -1484,6 +1511,12 @@ static int gen8_ppgtt_init(struct i915_hw_ppgtt *ppgtt) trace_i915_page_directory_pointer_entry_alloc(&ppgtt->base, 0, 0, GEN8_PML4E_SHIFT); + + if (intel_vgpu_active(ppgtt->base.dev)) { + ret = gen8_preallocate_top_level_pdps(ppgtt); + if (ret) + goto free_scratch; + } } return 0; diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c index 1af84c5..258af9b 100644 --- a/drivers/gpu/drm/i915/intel_lrc.c +++ b/drivers/gpu/drm/i915/intel_lrc.c @@ -1540,7 +1540,8 @@ static int gen8_emit_bb_start(struct drm_i915_gem_request *req, * not needed in 48-bit.*/ if (req->ctx->ppgtt && (intel_ring_flag(req->ring) & req->ctx->ppgtt->pd_dirty_rings)) { - if (!USES_FULL_48BIT_PPGTT(req->i915)) { + if (!USES_FULL_48BIT_PPGTT(req->i915) && + !intel_vgpu_active(req->i915->dev)) { ret = intel_logical_ring_emit_pdps(req); if (ret) return ret; -- 2.7.4