From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 5E7DF568528 for ; Tue, 22 Sep 2026 16:42:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790095340; cv=none; b=VVJIHOljKWsIRpr6eTwRs6eiksCQNiwHQJmt6/4iPYqoe7XBqYochLJwKZHKIpkj+9QZZQuZAci0v0Kmilh3G0F/drSqhbFKV9irsI3RZcyNI1dKo/O2brYrvJ7EJLOmf7n5Y7Ib9Rv6tq8b7ZIKARJd0XMsaPtlcEL/cpJ/Od4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790095340; c=relaxed/simple; bh=d/Mpn1ZpFaNOER/CgAQ3D20zXsFpahTQPNfzJEQeDiY=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=qwDjRmFQPlHEyzLbiaY7Kgg1ncfMJ6zTtqPf/6OTf9o6Fz4SygyFxEBhUkZQizMPA1MFXEvMBYFY2Xpoa4O3mZhSG29t9q6W2duUHM4/BHtd+clMwcoXsD5kJvbejktTV5yN/4U5vvN2+Cz8z5yjecbLksKuHOBYHOtSYsVPygs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b=Z7r7rrhy; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b="Z7r7rrhy" Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 052821576 for ; Tue, 22 Sep 2026 09:42:14 -0700 (PDT) Received: from [10.2.11.34] (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 4583A3F632 for ; Tue, 22 Sep 2026 09:42:17 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1790095337; bh=d/Mpn1ZpFaNOER/CgAQ3D20zXsFpahTQPNfzJEQeDiY=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Z7r7rrhymBcpUc+D3A2JX/GPvKIHWixfKbMFLiUcIzb3lt/a1u92VicUB7Re+vzwn 9WGdS/kXEelxIu450IBp6BXpiWx+RuWQsLTbVPXut5YzQZxA1ipU9JqPP9P8QtS3Zw swEY1B47v+VZFoPsB6aYg3MXYkKDvz6Wqpg077h4= Date: Tue, 22 Sep 2026 17:42:05 +0100 From: Liviu Dudau To: Boris Brezillon Cc: Steven Price , =?utf-8?Q?Adri=C3=A1n?= Larumbe , Akash Goel , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 3/4] drm/panthor: Consolidate the is-huge-page-mapping test Message-ID: References: <20260917-panthor-fix-partial-unmap-v1-0-c7008f15fea3@collabora.com> <20260917-panthor-fix-partial-unmap-v1-3-c7008f15fea3@collabora.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20260917-panthor-fix-partial-unmap-v1-3-c7008f15fea3@collabora.com> On Thu, Sep 17, 2026 at 02:33:45PM +0200, Boris Brezillon wrote: > Right now the logic to determine whether a given VA in the drm_gpuva > being unmapped is a huge page mapping or not is scattered > in two functions: unmap_hugepage_align() and > iova_mapped_as_huge_page(). This makes it harder to reason about the > logic being implemented for very little gain (some simple checks being > done twice), so let's consolidate all the checks related to huge page > mapping testing in iova_mapped_as_huge_page() and leave > unmap_hugepage_align() as a simple user of this helper that aligns the > area to unmap based on the return of iova_mapped_as_huge_page(). > > Signed-off-by: Boris Brezillon Reviewed-by: Liviu Dudau Best regards, Liviu > --- > drivers/gpu/drm/panthor/panthor_mmu.c | 57 +++++++++++++++++------------------ > 1 file changed, 28 insertions(+), 29 deletions(-) > > diff --git a/drivers/gpu/drm/panthor/panthor_mmu.c b/drivers/gpu/drm/panthor/panthor_mmu.c > index 6cef954e2cba..d2897099763e 100644 > --- a/drivers/gpu/drm/panthor/panthor_mmu.c > +++ b/drivers/gpu/drm/panthor/panthor_mmu.c > @@ -2301,10 +2301,11 @@ iova_mapped_as_huge_page(struct drm_gpuva *mapping, u64 va) > u64 aligned_va = ALIGN_DOWN(va, SZ_2M); > pgoff_t bo_offset; > > - /* If the 2M-aligned VA is outside the mapping being tested, we know > - * it's not a huge map. > + /* If the 2M section being tested is crossing the mapping boundary > + * we know it's not a huge map. > */ > - if (aligned_va < mapping->va.addr) > + if (aligned_va < mapping->va.addr || > + aligned_va + SZ_2M > mapping->va.addr + mapping->va.range) > return false; > > bo_offset = aligned_va - mapping->va.addr + mapping->gem.offset; > @@ -2337,10 +2338,21 @@ iova_mapped_as_huge_page(struct drm_gpuva *mapping, u64 va) > return false; > } else { > const struct page *pg = bo->backing.pages[bo_offset >> PAGE_SHIFT]; > + struct panthor_vma *vma = container_of(mapping, struct panthor_vma, base); > + bool is_sparse = vma->flags & DRM_PANTHOR_VM_BIND_OP_MAP_SPARSE; > > - /* In case of shmem backing, we know we can only have a huge mapping > - * if the bo_offset is 2M aligned, meaning we can skip the folio size > - * check if it's not the case. > + /* If the unmapped VMA stands for a sparse mapping, always > + * assume the backing storage is a THP, since the overhead of > + * unmapping 2MiB worth of 4KiB pages and remapping some of > + * them is offset by the logic of working out whether it's > + * the opposite case right below. > + */ > + if (is_sparse) > + return true; > + > + /* In case of shmem backing, we know we can only have a huge > + * mapping if the bo_offset is 2M aligned, meaning we can skip > + * the folio size check if it's not the case. > */ > if (!IS_ALIGNED(bo_offset, SZ_2M)) > return false; > @@ -2353,36 +2365,23 @@ static void > unmap_hugepage_align(const struct drm_gpuva_op_remap *op, > u64 *unmap_start, u64 *unmap_range) > { > - struct panthor_vma *unmap_vma = container_of(op->unmap->va, struct panthor_vma, base); > - bool is_sparse = unmap_vma->flags & DRM_PANTHOR_VM_BIND_OP_MAP_SPARSE; > - u64 aligned_unmap_start, aligned_unmap_end, unmap_end; > - > - unmap_end = *unmap_start + *unmap_range; > - aligned_unmap_start = ALIGN_DOWN(*unmap_start, SZ_2M); > - aligned_unmap_end = ALIGN(unmap_end, SZ_2M); > + u64 unmap_end = *unmap_start + *unmap_range; > > /* If we're dealing with a huge page, make sure the unmap region is > - * aligned on the start of the page. If the unmapped VMA stands for > - * a sparse mapping, always assume the backing storage is a THP, since > - * the overhead of unmapping 2MiB worth of 4KiB pages and remapping > - * some of them is offset by the logic of working out whether it's > - * the opposite case right below. This also holds true for op->next. > + * aligned on the start of the page. > */ > - if (op->prev && aligned_unmap_start < *unmap_start && > - op->prev->va.addr <= aligned_unmap_start && > - (is_sparse || iova_mapped_as_huge_page(op->unmap->va, *unmap_start))) { > - *unmap_range += *unmap_start - aligned_unmap_start; > - *unmap_start = aligned_unmap_start; > - } > + if (op->prev && !IS_ALIGNED(*unmap_start, SZ_2M) && > + iova_mapped_as_huge_page(op->unmap->va, *unmap_start)) > + *unmap_start = ALIGN_DOWN(*unmap_start, SZ_2M); > > /* If we're dealing with a huge page, make sure the unmap region is > * aligned on the end of the page. > */ > - if (op->next && aligned_unmap_end > unmap_end && > - op->next->va.addr + op->next->va.range >= aligned_unmap_end && > - (is_sparse || iova_mapped_as_huge_page(op->unmap->va, unmap_end - 1))) { > - *unmap_range += aligned_unmap_end - unmap_end; > - } > + if (op->next && !IS_ALIGNED(unmap_end, SZ_2M) && > + iova_mapped_as_huge_page(op->unmap->va, unmap_end - 1)) > + unmap_end = ALIGN(unmap_end, SZ_2M); > + > + *unmap_range = unmap_end - *unmap_start; > } > > static int panthor_gpuva_sm_step_remap(struct drm_gpuva_op *op, > > -- > 2.55.0 > -- ==================== | I would like to | | fix the world, | | but they're not | | giving me the | \ source code! / --------------- ¯\_(ツ)_/¯