From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.223.131]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D45A53D72 for ; Sun, 26 May 2024 11:04:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=195.135.223.131 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1716721501; cv=none; b=THCX9v8Dv+AjgI2W5EJaLvVB6avTZ51FOq2PKsUhlOnD0l7pF9EqEiJUvhlrB8TPAlyd8w6pYw3bZBsQC54lXkY0FH/IzrLgWRtElK9EnMlRfYqctBIzWHIWcwWpWpA4HBCbTRopy2ccUz+Ccmbn/mlh7aYAbzWUvf7hK4KW6FA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1716721501; c=relaxed/simple; bh=yGmmIuLTcFqjskdyA7AomRU8Ndv6IVRbK4wBd0fRrCQ=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=K+KVvS/cXWnzmn5FuwgCXzg0h12hsMFncJgCCZdkO75d7/OVQMkIM6+SvRXdkJxo1+qLc6IgX8j3nx4EOtxxP0NGGQRopJBgRbcTk68C47BKDDDL20o9arbHZWVPBoaFraIIjNvzabyE+wCwntWcwu97VhH9X3/MOmW/HM94YDA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=suse.de; spf=pass smtp.mailfrom=suse.de; arc=none smtp.client-ip=195.135.223.131 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=suse.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=suse.de Received: from imap1.dmz-prg2.suse.org (imap1.dmz-prg2.suse.org [IPv6:2a07:de40:b281:104:10:150:64:97]) (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) by smtp-out2.suse.de (Postfix) with ESMTPS id D4B6B5C908; Sun, 26 May 2024 11:04:57 +0000 (UTC) Authentication-Results: smtp-out2.suse.de; none Received: from imap1.dmz-prg2.suse.org (localhost [127.0.0.1]) (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) by imap1.dmz-prg2.suse.org (Postfix) with ESMTPS id 4C7C913A51; Sun, 26 May 2024 11:04:57 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id pqKBD1kXU2ZiZgAAD6G6ig (envelope-from ); Sun, 26 May 2024 11:04:57 +0000 Date: Sun, 26 May 2024 13:04:51 +0200 From: Oscar Salvador To: Christophe Leroy Cc: Andrew Morton , Jason Gunthorpe , Peter Xu , Michael Ellerman , Nicholas Piggin , linux-kernel@vger.kernel.org, linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org Subject: Re: [RFC PATCH v3 00/16] Reimplement huge pages without hugepd on powerpc (8xx, e500, book3s/64) Message-ID: References: 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=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Pre-Result: action=no action; module=replies; Message is reply to one we originated X-Spam-Level: X-Spamd-Result: default: False [-4.00 / 50.00]; REPLY(-4.00)[] X-Spam-Flag: NO X-Spam-Score: -4.00 X-Rspamd-Queue-Id: D4B6B5C908 X-Rspamd-Server: rspamd2.dmz-prg2.suse.org X-Rspamd-Pre-Result: action=no action; module=replies; Message is reply to one we originated X-Rspamd-Action: no action On Sun, May 26, 2024 at 11:22:20AM +0200, Christophe Leroy wrote: > This is the continuation of the RFC v1 series "Reimplement huge pages > without hugepd on powerpc 8xx". It now get rid of hugepd completely > after handling also e500 and book3s/64 > > Also see https://github.com/linuxppc/issues/issues/483 > > Unlike most architectures, powerpc 8xx HW requires a two-level > pagetable topology for all page sizes. So a leaf PMD-contig approach > is not feasible as such. > > Possible sizes on 8xx are 4k, 16k, 512k and 8M. > > First level (PGD/PMD) covers 4M per entry. For 8M pages, two PMD entries > must point to a single entry level-2 page table. Until now that was > done using hugepd. This series changes it to use standard page tables > where the entry is replicated 1024 times on each of the two pagetables > refered by the two associated PMD entries for that 8M page. > > For e500 and book3s/64 there are less constraints because it is not > tied to the HW assisted tablewalk like on 8xx, so it is easier to use > leaf PMDs (and PUDs). > > On e500 the supported page sizes are 4M, 16M, 64M, 256M and 1G. All at > PMD level on e500/32 (mpc85xx) and mix of PMD and PUD for e500/64. We > encode page size with 4 available bits in PTE entries. On e300/32 PGD > entries size is increases to 64 bits in order to allow leaf-PMD entries > because PTE are 64 bits on e500. > > On book3s/64 only the hash-4k mode is concerned. It supports 16M pages > as cont-PMD and 16G pages as cont-PUD. In other modes (radix-4k, radix-6k > and hash-64k) the sizes match with PMD and PUD sizes so that's just leaf > entries. The hash processing make things a bit more complex. To ease > things, __hash_page_huge() is modified to bail out when DIRTY or ACCESSED > bits are missing, leaving it to mm core to fix it. > > Global changes in v3: > - Removed patches 1 and 2 > - Squashed patch 11 into patch 5 > - Replaced patches 12 and 13 with a series from Michael > - Reordered patches a bit to have more general patches up front > > For more details on changes, see in each patch. > > Christophe Leroy (15): > mm: Define __pte_leaf_size() to also take a PMD entry > mm: Provide mm_struct and address to huge_ptep_get() > powerpc/mm: Remove _PAGE_PSIZE > powerpc/mm: Fix __find_linux_pte() on 32 bits with PMD leaf entries > powerpc/mm: Allow hugepages without hugepd > powerpc/8xx: Fix size given to set_huge_pte_at() > powerpc/8xx: Rework support for 8M pages using contiguous PTE entries > powerpc/8xx: Simplify struct mmu_psize_def > powerpc/e500: Remove enc and ind fields from struct mmu_psize_def > powerpc/e500: Switch to 64 bits PGD on 85xx (32 bits) > powerpc/e500: Encode hugepage size in PTE bits > powerpc/e500: Use contiguous PMD instead of hugepd > powerpc/64s: Use contiguous PMD/PUD instead of HUGEPD > powerpc/mm: Remove hugepd leftovers > mm: Remove CONFIG_ARCH_HAS_HUGEPD I glanced over it and it looks much better, not having to fiddle with other arch code and generic declarations is a big plus. I plan to do a proper review tomorrow. Thanks for working on this Christophe! -- Oscar Salvador SUSE Labs