From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 462DAC369C2 for ; Thu, 24 Apr 2025 14:39:57 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 0C61C10E82C; Thu, 24 Apr 2025 14:39:57 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=intel.com header.i=@intel.com header.b="fk/8LtJZ"; dkim-atps=neutral Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.13]) by gabe.freedesktop.org (Postfix) with ESMTPS id 4515E10E446; Thu, 24 Apr 2025 14:39:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1745505597; x=1777041597; h=message-id:subject:from:to:cc:date:in-reply-to: references:content-transfer-encoding:mime-version; bh=2QcUvzorWSznQeELTM23X6+VWJ/i3tj1ZcE3km2ZHdU=; b=fk/8LtJZc7P2WLTxSqgsCvxiFRY/HMP6Ur4Xo6l6Xc+236itP0EylW3y DBAG+C88Oe7c7nOh4U+6BExADlOmiVNSIPyYbIHsNOrWzQP4AIxkKchFM LlmNOlLCGVffl7tL0RUbCQ2jFc5hrI3xUDDzcMfdju/cfvhz4QWr4ThKE /Uk7PBu5C1uZy7T5Zj4EXlxQdji/UC2El6SjNBgqkz54IWQGH08GPT+dy +YnCT/SJERICLfYIG8OG1yZPL8AVTJrq0PK1Z1MPeoEPtgK2hcic3hfqb 43XkasXiHWildddPCqDWVgW17H+wQG3d7aa7FZ9OlR+Khs+XNg+hgq4JA Q==; X-CSE-ConnectionGUID: 2cXu01b1RByqVvZUWJ+KDg== X-CSE-MsgGUID: Id7OBjx2TEi/sCuNcxJHJQ== X-IronPort-AV: E=McAfee;i="6700,10204,11413"; a="58136186" X-IronPort-AV: E=Sophos;i="6.15,236,1739865600"; d="scan'208";a="58136186" Received: from orviesa003.jf.intel.com ([10.64.159.143]) by orvoesa105.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 24 Apr 2025 07:39:25 -0700 X-CSE-ConnectionGUID: gAbWWZ96Qjib+K8WoZCGpg== X-CSE-MsgGUID: BZNn/OXrSK+EWdSJPB0CKw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.15,236,1739865600"; d="scan'208";a="137497055" Received: from vpanait-mobl.ger.corp.intel.com (HELO [10.245.246.20]) ([10.245.246.20]) by ORVIESA003-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 24 Apr 2025 07:39:24 -0700 Message-ID: <1391a2ab3cbf8b690f1ec371cdc932032a647645.camel@linux.intel.com> Subject: Re: [PATCH v4 2/5] drm/xe: Strict migration policy for atomic SVM faults From: Thomas =?ISO-8859-1?Q?Hellstr=F6m?= To: Matthew Brost , intel-xe@lists.freedesktop.org Cc: dri-devel@lists.freedesktop.org, himal.prasad.ghimiray@intel.com Date: Thu, 24 Apr 2025 16:39:21 +0200 In-Reply-To: <20250422170415.584662-3-matthew.brost@intel.com> References: <20250422170415.584662-1-matthew.brost@intel.com> <20250422170415.584662-3-matthew.brost@intel.com> Organization: Intel Sweden AB, Registration Number: 556189-6027 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.54.3 (3.54.3-1.fc41) MIME-Version: 1.0 X-BeenThere: intel-xe@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel Xe graphics driver List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-xe-bounces@lists.freedesktop.org Sender: "Intel-xe" On Tue, 2025-04-22 at 10:04 -0700, Matthew Brost wrote: > Mixing GPU and CPU atomics does not work unless a strict migration > policy of GPU atomics must be device memory. Enforce a policy of must > be > in VRAM with a retry loop of 2 attempts, if retry loop fails abort > fault. >=20 > v2: > =C2=A0- Only retry migration on atomics > =C2=A0- Drop alway migrate modparam > v3: > =C2=A0- Only set vram_only on DGFX (Himal) > =C2=A0- Bail on get_pages failure if vram_only and retry count exceeded > (Himal) > =C2=A0- s/vram_only/devmem_only > =C2=A0- Update xe_svm_range_is_valid to accept devmem_only argument > v4: > =C2=A0- Fix logic bug get_pages failure >=20 > Signed-off-by: Himal Prasad Ghimiray > > Signed-off-by: Matthew Brost > --- > =C2=A0drivers/gpu/drm/xe/xe_module.c |=C2=A0 3 -- > =C2=A0drivers/gpu/drm/xe/xe_module.h |=C2=A0 1 - > =C2=A0drivers/gpu/drm/xe/xe_svm.c=C2=A0=C2=A0=C2=A0 | 89 ++++++++++++++++= +++++++++------- > -- > =C2=A0drivers/gpu/drm/xe/xe_svm.h=C2=A0=C2=A0=C2=A0 |=C2=A0 5 -- > =C2=A04 files changed, 65 insertions(+), 33 deletions(-) >=20 > diff --git a/drivers/gpu/drm/xe/xe_module.c > b/drivers/gpu/drm/xe/xe_module.c > index 05c7d0ae6d83..1c4dfafbcd0b 100644 > --- a/drivers/gpu/drm/xe/xe_module.c > +++ b/drivers/gpu/drm/xe/xe_module.c > @@ -33,9 +33,6 @@ struct xe_modparam xe_modparam =3D { > =C2=A0module_param_named(svm_notifier_size, xe_modparam.svm_notifier_size= , > uint, 0600); > =C2=A0MODULE_PARM_DESC(svm_notifier_size, "Set the svm notifier size(in > MiB), must be power of 2"); > =C2=A0 > -module_param_named(always_migrate_to_vram, > xe_modparam.always_migrate_to_vram, bool, 0444); > -MODULE_PARM_DESC(always_migrate_to_vram, "Always migrate to VRAM on > GPU fault"); > - =C2=A0module_param_named_unsafe(force_execlist, > xe_modparam.force_execlist, bool, 0444); > =C2=A0MODULE_PARM_DESC(force_execlist, "Force Execlist submission"); > =C2=A0 > diff --git a/drivers/gpu/drm/xe/xe_module.h > b/drivers/gpu/drm/xe/xe_module.h > index 84339e509c80..5a3bfea8b7b4 100644 > --- a/drivers/gpu/drm/xe/xe_module.h > +++ b/drivers/gpu/drm/xe/xe_module.h > @@ -12,7 +12,6 @@ > =C2=A0struct xe_modparam { > =C2=A0 bool force_execlist; > =C2=A0 bool probe_display; > - bool always_migrate_to_vram; > =C2=A0 u32 force_vram_bar_size; > =C2=A0 int guc_log_level; > =C2=A0 char *guc_firmware_path; > diff --git a/drivers/gpu/drm/xe/xe_svm.c > b/drivers/gpu/drm/xe/xe_svm.c > index 890f6b2f40e9..f749ae367a8f 100644 > --- a/drivers/gpu/drm/xe/xe_svm.c > +++ b/drivers/gpu/drm/xe/xe_svm.c > @@ -650,9 +650,11 @@ void xe_svm_fini(struct xe_vm *vm) > =C2=A0} > =C2=A0 > =C2=A0static bool xe_svm_range_is_valid(struct xe_svm_range *range, > - =C2=A0 struct xe_tile *tile) > + =C2=A0 struct xe_tile *tile, > + =C2=A0 bool devmem_only) > =C2=A0{ > - return (range->tile_present & ~range->tile_invalidated) & > BIT(tile->id); > + return ((range->tile_present & ~range->tile_invalidated) & > BIT(tile->id)) > + && (!devmem_only || range- > >base.flags.migrate_devmem); > =C2=A0} So let's say devmem_only is true here, and range- >base.flags.migrate_devmem is false. Wouldn't that mean the range is unusable and needs to be freed and re-allocated? Also another thing going back to older code, it seems like range- >tile_invalidated is protected by the notifier lock, so shouldn't we assert that to be held in the function? It seems not to be held further below: > =C2=A0 > =C2=A0#if IS_ENABLED(CONFIG_DRM_XE_DEVMEM_MIRROR) > @@ -726,6 +728,35 @@ static int xe_svm_alloc_vram(struct xe_vm *vm, > struct xe_tile *tile, > =C2=A0} > =C2=A0#endif > =C2=A0 > +static bool supports_4K_migration(struct xe_device *xe) > +{ > + if (xe->info.vram_flags & XE_VRAM_FLAGS_NEED64K) > + return false; > + > + return true; > +} Do we have any hardware that supports pagefaults but not 4K VRAM pages? > + > +static bool xe_svm_range_needs_migrate_to_vram(struct xe_svm_range > *range, > + =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 struct xe_vma *vma) > +{ > + struct xe_vm *vm =3D range_to_vm(&range->base); > + u64 range_size =3D xe_svm_range_size(range); > + > + if (!range->base.flags.migrate_devmem) > + return false; > + > + if (xe_svm_range_in_vram(range)) { > + drm_dbg(&vm->xe->drm, "Range is already in VRAM\n"); > + return false; > + } > + > + if (range_size <=3D SZ_64K && !supports_4K_migration(vm->xe)) > { > + drm_dbg(&vm->xe->drm, "Platform doesn't support > SZ_4K range migration\n"); > + return false; > + } > + > + return true; > +} > =C2=A0 > =C2=A0/** > =C2=A0 * xe_svm_handle_pagefault() - SVM handle page fault > @@ -750,12 +781,15 @@ int xe_svm_handle_pagefault(struct xe_vm *vm, > struct xe_vma *vma, > =C2=A0 IS_ENABLED(CONFIG_DRM_XE_DEVMEM_MIRROR), > =C2=A0 .check_pages_threshold =3D IS_DGFX(vm->xe) && > =C2=A0 IS_ENABLED(CONFIG_DRM_XE_DEVMEM_MIRROR) ? > SZ_64K : 0, > + .devmem_only =3D atomic && IS_DGFX(vm->xe) && > + IS_ENABLED(CONFIG_DRM_XE_DEVMEM_MIRROR), > =C2=A0 }; > =C2=A0 struct xe_svm_range *range; > =C2=A0 struct drm_gpusvm_range *r; > =C2=A0 struct drm_exec exec; > =C2=A0 struct dma_fence *fence; > =C2=A0 struct xe_tile *tile =3D gt_to_tile(gt); > + int migrate_try_count =3D ctx.devmem_only ? 3 : 1; > =C2=A0 ktime_t end =3D 0; > =C2=A0 int err; > =C2=A0 > @@ -777,23 +811,26 @@ int xe_svm_handle_pagefault(struct xe_vm *vm, > struct xe_vma *vma, > =C2=A0 return PTR_ERR(r); > =C2=A0 > =C2=A0 range =3D to_xe_range(r); > - if (xe_svm_range_is_valid(range, tile)) > + if (xe_svm_range_is_valid(range, tile, ctx.devmem_only)) Requires notifier lock. Also see comment on re-allocating the range above. > =C2=A0 return 0; > =C2=A0 > =C2=A0 range_debug(range, "PAGE FAULT"); > =C2=A0 > - /* XXX: Add migration policy, for now migrate range once */ > - if (!range->skip_migrate && range->base.flags.migrate_devmem > && > - =C2=A0=C2=A0=C2=A0 xe_svm_range_size(range) >=3D SZ_64K) { > - range->skip_migrate =3D true; > - > + if (--migrate_try_count >=3D 0 && > + =C2=A0=C2=A0=C2=A0 xe_svm_range_needs_migrate_to_vram(range, vma) Requires notifier lock. Should we have some sort of timeout instead of a try-count? Perhaps as a last resort fall back to a 4K range? /Thomas > ) { > =C2=A0 err =3D xe_svm_alloc_vram(vm, tile, range, &ctx); > =C2=A0 if (err) { > - drm_dbg(&vm->xe->drm, > - "VRAM allocation failed, falling > back to " > - "retrying fault, asid=3D%u, > errno=3D%pe\n", > - vm->usm.asid, ERR_PTR(err)); > - goto retry; > + if (migrate_try_count || !ctx.devmem_only) { > + drm_dbg(&vm->xe->drm, > + "VRAM allocation failed, > falling back to retrying fault, asid=3D%u, errno=3D%pe\n", > + vm->usm.asid, ERR_PTR(err)); > + goto retry; > + } else { > + drm_err(&vm->xe->drm, > + "VRAM allocation failed, > retry count exceeded, asid=3D%u, errno=3D%pe\n", > + vm->usm.asid, ERR_PTR(err)); > + return err; > + } > =C2=A0 } > =C2=A0 } > =C2=A0 > @@ -801,15 +838,22 @@ int xe_svm_handle_pagefault(struct xe_vm *vm, > struct xe_vma *vma, > =C2=A0 err =3D drm_gpusvm_range_get_pages(&vm->svm.gpusvm, r, &ctx); > =C2=A0 /* Corner where CPU mappings have changed */ > =C2=A0 if (err =3D=3D -EOPNOTSUPP || err =3D=3D -EFAULT || err =3D=3D -EP= ERM) { > - if (err =3D=3D -EOPNOTSUPP) { > - range_debug(range, "PAGE FAULT - EVICT > PAGES"); > - drm_gpusvm_range_evict(&vm->svm.gpusvm, > &range->base); > + if (migrate_try_count > 0 || !ctx.devmem_only) { > + if (err =3D=3D -EOPNOTSUPP) { > + range_debug(range, "PAGE FAULT - > EVICT PAGES"); > + drm_gpusvm_range_evict(&vm- > >svm.gpusvm, > + =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 &range- > >base); > + } > + drm_dbg(&vm->xe->drm, > + "Get pages failed, falling back to > retrying, asid=3D%u, gpusvm=3D%p, errno=3D%pe\n", > + vm->usm.asid, &vm->svm.gpusvm, > ERR_PTR(err)); > + range_debug(range, "PAGE FAULT - RETRY > PAGES"); > + goto retry; > + } else { > + drm_err(&vm->xe->drm, > + "Get pages failed, retry count > exceeded, asid=3D%u, gpusvm=3D%p, errno=3D%pe\n", > + vm->usm.asid, &vm->svm.gpusvm, > ERR_PTR(err)); > =C2=A0 } > - drm_dbg(&vm->xe->drm, > - "Get pages failed, falling back to retrying, > asid=3D%u, gpusvm=3D%p, errno=3D%pe\n", > - vm->usm.asid, &vm->svm.gpusvm, > ERR_PTR(err)); > - range_debug(range, "PAGE FAULT - RETRY PAGES"); > - goto retry; > =C2=A0 } > =C2=A0 if (err) { > =C2=A0 range_debug(range, "PAGE FAULT - FAIL PAGE > COLLECT"); > @@ -843,9 +887,6 @@ int xe_svm_handle_pagefault(struct xe_vm *vm, > struct xe_vma *vma, > =C2=A0 } > =C2=A0 drm_exec_fini(&exec); > =C2=A0 > - if (xe_modparam.always_migrate_to_vram) > - range->skip_migrate =3D false; > - > =C2=A0 dma_fence_wait(fence, false); > =C2=A0 dma_fence_put(fence); > =C2=A0 > diff --git a/drivers/gpu/drm/xe/xe_svm.h > b/drivers/gpu/drm/xe/xe_svm.h > index 3d441eb1f7ea..0e1f376a7471 100644 > --- a/drivers/gpu/drm/xe/xe_svm.h > +++ b/drivers/gpu/drm/xe/xe_svm.h > @@ -39,11 +39,6 @@ struct xe_svm_range { > =C2=A0 * range. Protected by GPU SVM notifier lock. > =C2=A0 */ > =C2=A0 u8 tile_invalidated; > - /** > - * @skip_migrate: Skip migration to VRAM, protected by GPU > fault handler > - * locking. > - */ > - u8 skip_migrate :1; > =C2=A0}; > =C2=A0 > =C2=A0/**