From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bali.collaboradmins.com (bali.collaboradmins.com [148.251.105.195]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0A5FB472F9F for ; Thu, 24 Sep 2026 11:04:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=148.251.105.195 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790247896; cv=none; b=EwWoKmqrpIiEf27Lh6mtVkVvQpzBXBKh+WPW5jQM4Fj67AmswP9gmaKfaG8tPKv7o3n7BnsehXW5EUzoyBcr6n5hbNvGQls31doGQbI8u5UjvkcmMMvEU+0zaeRyWNbwaFklSfRLrZCf7MP4wDS4n40lIuacRbp0BRbyp/phamY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790247896; c=relaxed/simple; bh=XXFQmfxbeg12M2OgKN8dJ9l8UIV4ldaUbZSuiynE7b4=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=kqANcM5izBMkc4Fz9EMfqlTux4DvCPNVl8AX4j9YQDa8pu2hX6e4cBZchWs2qPG/S8o0av6dnd6ubJR5xEWkM0yBAhQkGUCg36Rx7HehfxxKwx20GQuMPGz/GJFYjm4liJ+61BGmRKQunohCA4CDV+nbnqS1BbI6bc5WixXMkAo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=collabora.com; spf=pass smtp.mailfrom=collabora.com; dkim=pass (2048-bit key) header.d=collabora.com header.i=@collabora.com header.b=oPEz3aWT; arc=none smtp.client-ip=148.251.105.195 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=collabora.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=collabora.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=collabora.com header.i=@collabora.com header.b="oPEz3aWT" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1790247889; bh=XXFQmfxbeg12M2OgKN8dJ9l8UIV4ldaUbZSuiynE7b4=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=oPEz3aWTOD7BORoXvzIu8ZcdFFTYDR65DWxRg6vPai1wDhU70fz7IgiTAI/n2VvcF AI/sDLpbXbEgWG4QZ2+tmah/F7SgFxptiITV887SDZG9ciMHQbdePrn9DtmWwDoACG 7uQNuNQid/AsK3XQbXaWmV1qyGzFvngvTrdkijVPxwhq4If7aDi5uPXKfsT5iEOk3X /KrkNEYeJob2TT6zzTH4Yo0ab3Qj1o79BV1FL3meTVbnYLA0PxOLvI09uL0QVZaByX qm84l1crTV9aWsPIbBJRAkm5gqT7AChFcaM4SnA6RWRs6Tksw6Jjfi8qdA97IP8a9P TnPNHuqPprXug== Received: from fedora-32.home (unknown [100.64.0.11]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange x25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: bbrezillon) by bali.collaboradmins.com (Postfix) with ESMTPSA id 9DD9117E0B0F; Thu, 24 Sep 2026 13:04:48 +0200 (CEST) From: Boris Brezillon Date: Thu, 24 Sep 2026 13:04:41 +0200 Subject: [PATCH v2 4/5] drm/panthor: Actually check huge-page mapping on sparse regions 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-Transfer-Encoding: 7bit Message-Id: <20260924-panthor-fix-partial-unmap-v2-4-59a68a1f9e14@collabora.com> References: <20260924-panthor-fix-partial-unmap-v2-0-59a68a1f9e14@collabora.com> In-Reply-To: <20260924-panthor-fix-partial-unmap-v2-0-59a68a1f9e14@collabora.com> To: Steven Price , Liviu Dudau , =?utf-8?q?Adri=C3=A1n_Larumbe?= , Akash Goel Cc: Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, Boris Brezillon X-Mailer: b4 0.15.2 X-Developer-Signature: v=1; a=ed25519-sha256; t=1790247886; l=2529; i=boris.brezillon@collabora.com; s=20260429; h=from:subject:message-id; bh=XXFQmfxbeg12M2OgKN8dJ9l8UIV4ldaUbZSuiynE7b4=; b=l/2yTWBNMeOJtPU6XlpqndFiYPPeycUcG7eZjtPC93NZDKhi11vFCOgO9xHR4iERb/9oXymjD Hcq/8fsUb4/C1JTK92i1i/K6v53+WNIjkB7qYNx9lkrI/NVzvWkvgah X-Developer-Key: i=boris.brezillon@collabora.com; a=ed25519; pk=eN+ORdOgQY7d5U+0kA8h5bf67XdD8bhKbjD/TCHexSY= With the recent changes to iova_mapped_as_huge_page(), the check for huge-page mapping of sparse BOs is actually simple: - for a sparse mapping, we know the BO offset any VA in this regions is va & (SZ_2M - 1) - the VA we're searching the BO offset for is the 2M-aligned aligned_va value This guarantees that the BO offset to check is always zero in that case. This is simple enough to let the code check if page 0 is a huge page and save the unmap+map dance when the dummy BO is not backed by a a huge page. So let's do that and kill the comment that says it's too complicated. Reviewed-by: Liviu Dudau Reviewed-by: Akash Goel Signed-off-by: Boris Brezillon --- drivers/gpu/drm/panthor/panthor_mmu.c | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-) diff --git a/drivers/gpu/drm/panthor/panthor_mmu.c b/drivers/gpu/drm/panthor/panthor_mmu.c index d2897099763e..01564d250adf 100644 --- a/drivers/gpu/drm/panthor/panthor_mmu.c +++ b/drivers/gpu/drm/panthor/panthor_mmu.c @@ -2337,18 +2337,18 @@ 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; + const struct page *pg; - /* 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. + /* BO offset on a sparse mapping is chosen so that 2M-aligned + * VAs point to the start of the BO. Since aligned_va (the + * address we check huge-page against) is 2M-aligned, the BO + * offset is guaranteed to be zero. + * Check panthor_fix_sparse_map_offset() for more details. */ if (is_sparse) - return true; + bo_offset = 0; /* 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 @@ -2357,6 +2357,7 @@ iova_mapped_as_huge_page(struct drm_gpuva *mapping, u64 va) if (!IS_ALIGNED(bo_offset, SZ_2M)) return false; + pg = bo->backing.pages[bo_offset >> PAGE_SHIFT]; return folio_size(page_folio(pg)) >= SZ_2M; } } -- 2.55.0