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[79.27.108.198]) by smtp.gmail.com with ESMTPSA id m7-20020a056000008700b00222ed7ea203sm9805502wrx.100.2022.08.11.08.30.53 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 11 Aug 2022 08:30:55 -0700 (PDT) From: "Fabio M. De Francesco" To: Jani Nikula , Joonas Lahtinen , Rodrigo Vivi , Tvrtko Ursulin , David Airlie , Daniel Vetter , John Harrison , Matt Roper , Matthew Brost , Lucas De Marchi , Daniele Ceraolo Spurio , Matthew Auld , Ira Weiny , intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org Cc: "Fabio M. De Francesco" Subject: [PATCH 3/3] drm/i915/gem: Replace kmap() with kmap_local_page() Date: Thu, 11 Aug 2022 17:30:41 +0200 Message-Id: <20220811153041.12795-4-fmdefrancesco@gmail.com> X-Mailer: git-send-email 2.37.1 In-Reply-To: <20220811153041.12795-1-fmdefrancesco@gmail.com> References: <20220811153041.12795-1-fmdefrancesco@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org kmap() is being deprecated in favor of kmap_local_page(). There are two main problems with kmap(): (1) It comes with an overhead as mapping space is restricted and protected by a global lock for synchronization and (2) it also requires global TLB invalidation when the kmap=E2=80=99s pool wraps and it might block when the mapping space is fully utilized until a slot becomes available. With kmap_local_page() the mappings are per thread, CPU local, can take page faults, and can be called from any context (including interrupts). It is faster than kmap() in kernels with HIGHMEM enabled. Furthermore, the tasks can be preempted and, when they are scheduled to run again, the kernel virtual addresses are restored and are still valid. Since its use in i915/gem is safe everywhere, it should be preferred. Therefore, replace kmap() with kmap_local_page() in i915/gem. Suggested-by: Ira Weiny Signed-off-by: Fabio M. De Francesco --- drivers/gpu/drm/i915/gem/i915_gem_shmem.c | 6 ++---- drivers/gpu/drm/i915/gem/selftests/i915_gem_mman.c | 8 ++++---- 2 files changed, 6 insertions(+), 8 deletions(-) diff --git a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c b/drivers/gpu/drm/i9= 15/gem/i915_gem_shmem.c index 4eed3dd90ba8..2bc6ab9964ff 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c +++ b/drivers/gpu/drm/i915/gem/i915_gem_shmem.c @@ -640,16 +640,14 @@ i915_gem_object_create_shmem_from_data(struct drm_i91= 5_private *dev_priv, do { unsigned int len =3D min_t(typeof(size), size, PAGE_SIZE); struct page *page; - void *pgdata, *vaddr; + void *pgdata; =20 err =3D aops->write_begin(file, file->f_mapping, offset, len, &page, &pgdata); if (err < 0) goto fail; =20 - vaddr =3D kmap(page); - memcpy(vaddr, data, len); - kunmap(page); + memcpy_to_page(page, 0, data, len); =20 err =3D aops->write_end(file, file->f_mapping, offset, len, len, page, pgdata); diff --git a/drivers/gpu/drm/i915/gem/selftests/i915_gem_mman.c b/drivers/g= pu/drm/i915/gem/selftests/i915_gem_mman.c index 3ced9948a331..bb25b50b5688 100644 --- a/drivers/gpu/drm/i915/gem/selftests/i915_gem_mman.c +++ b/drivers/gpu/drm/i915/gem/selftests/i915_gem_mman.c @@ -153,7 +153,7 @@ static int check_partial_mapping(struct drm_i915_gem_ob= ject *obj, intel_gt_flush_ggtt_writes(to_gt(i915)); =20 p =3D i915_gem_object_get_page(obj, offset >> PAGE_SHIFT); - cpu =3D kmap(p) + offset_in_page(offset); + cpu =3D kmap_local_page(p) + offset_in_page(offset); drm_clflush_virt_range(cpu, sizeof(*cpu)); if (*cpu !=3D (u32)page) { pr_err("Partial view for %lu [%u] (offset=3D%llu, size=3D%u [%llu, row s= ize %u], fence=3D%d, tiling=3D%d, stride=3D%d) misalignment, expected write= to page (%llu + %u [0x%llx]) of 0x%x, found 0x%x\n", @@ -171,7 +171,7 @@ static int check_partial_mapping(struct drm_i915_gem_ob= ject *obj, } *cpu =3D 0; drm_clflush_virt_range(cpu, sizeof(*cpu)); - kunmap(p); + kunmap_local(cpu); =20 out: i915_gem_object_lock(obj, NULL); @@ -249,7 +249,7 @@ static int check_partial_mappings(struct drm_i915_gem_o= bject *obj, intel_gt_flush_ggtt_writes(to_gt(i915)); =20 p =3D i915_gem_object_get_page(obj, offset >> PAGE_SHIFT); - cpu =3D kmap(p) + offset_in_page(offset); + cpu =3D kmap_local_page(p) + offset_in_page(offset); drm_clflush_virt_range(cpu, sizeof(*cpu)); if (*cpu !=3D (u32)page) { pr_err("Partial view for %lu [%u] (offset=3D%llu, size=3D%u [%llu, row = size %u], fence=3D%d, tiling=3D%d, stride=3D%d) misalignment, expected writ= e to page (%llu + %u [0x%llx]) of 0x%x, found 0x%x\n", @@ -267,7 +267,7 @@ static int check_partial_mappings(struct drm_i915_gem_o= bject *obj, } *cpu =3D 0; drm_clflush_virt_range(cpu, sizeof(*cpu)); - kunmap(p); + kunmap_local(cpu); if (err) return err; =20 --=20 2.37.1