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 X-Spam-Level: X-Spam-Status: No, score=-18.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D171DC433ED for ; Wed, 12 May 2021 21:30:42 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 61EFE611C9 for ; Wed, 12 May 2021 21:30:42 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 61EFE611C9 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from list by lists.xenproject.org with outflank-mailman.126399.237959 (Exim 4.92) (envelope-from ) id 1lgwQt-0007Gg-4Z; Wed, 12 May 2021 21:30:19 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 126399.237959; Wed, 12 May 2021 21:30:19 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lgwQt-0007GZ-1U; Wed, 12 May 2021 21:30:19 +0000 Received: by outflank-mailman (input) for mailman id 126399; Wed, 12 May 2021 21:30:17 +0000 Received: from all-amaz-eas1.inumbo.com ([34.197.232.57] helo=us1-amaz-eas2.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lgwQr-0007GT-7i for xen-devel@lists.xenproject.org; Wed, 12 May 2021 21:30:17 +0000 Received: from mail.kernel.org (unknown [198.145.29.99]) by us1-amaz-eas2.inumbo.com (Halon) with ESMTPS id a6518a3d-b686-4252-a12a-5d89cf54ddfa; Wed, 12 May 2021 21:30:16 +0000 (UTC) Received: by mail.kernel.org (Postfix) with ESMTPSA id 0EAB1613E6; Wed, 12 May 2021 21:30:15 +0000 (UTC) X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: a6518a3d-b686-4252-a12a-5d89cf54ddfa DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1620855015; bh=4GO29E4P5CadwLaZmmzGQrRInrNcFgNOKyQmX0Qeh6M=; h=Date:From:To:cc:Subject:In-Reply-To:References:From; b=H7kB4nMlt4dT5hTPNVurw8KhB9GFLNAnp08qTFUxB60QGtv7ioFSlocbE9UWB1+rg wP4MixwiGLQlwkZyWNTQYY8pl5tb1WbMMdhF72YwtQIms2G5w5hnYG3SkJMcXnZOLY sO/EJxCUjgpbmB1k6KfpL3Ro0Hbx082+c8VvVfARJfpXf0p1f5oTyQFohT1WhfDHtp KO3m5A5gSRaDbpEyltrfw/9a0oCBnHmyaxfEbjpadBdZGhlZy5wVdPUZNKfd6eqSqU QUk9l1Dj+tNPshaw4cy7hr6R62cj9y9Msfatlbn5Ul9NDkT2gkIdGDDV64sCBOUdw4 dcJHArdEt2PRA== Date: Wed, 12 May 2021 14:30:14 -0700 (PDT) From: Stefano Stabellini X-X-Sender: sstabellini@sstabellini-ThinkPad-T480s To: Julien Grall cc: Stefano Stabellini , xen-devel@lists.xenproject.org, Wei.Chen@arm.com, Henry.Wang@arm.com, Penny.Zheng@arm.com, Bertrand.Marquis@arm.com, Julien Grall , Volodymyr Babchuk Subject: Re: [PATCH RFCv2 02/15] xen/arm: lpae: Use the generic helpers to defined the Xen PT helpers In-Reply-To: <94e364a7-de40-93ab-6cde-a2f493540439@xen.org> Message-ID: References: <20210425201318.15447-1-julien@xen.org> <20210425201318.15447-3-julien@xen.org> <94e364a7-de40-93ab-6cde-a2f493540439@xen.org> User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII On Wed, 12 May 2021, Julien Grall wrote: > Hi Stefano, > > On 11/05/2021 23:26, Stefano Stabellini wrote: > > On Sun, 25 Apr 2021, Julien Grall wrote: > > > From: Julien Grall > > > > > > Currently, Xen PT helpers are only working with 4KB page granularity > > > and open-code the generic helpers. To allow more flexibility, we can > > > re-use the generic helpers and pass Xen's page granularity > > > (PAGE_SHIFT). > > > > > > As Xen PT helpers are used in both C and assembly, we need to move > > > the generic helpers definition outside of the !__ASSEMBLY__ section. > > > > > > Note the aliases for each level are still kept for the time being so we > > > can avoid a massive patch to change all the callers. > > > > > > Signed-off-by: Julien Grall > > > > The patch is OK as is. I have a couple of suggestions for improvement > > below. If you feel like making them, good, otherwise I am also OK if you > > don't want to change anything. > > > > > > > --- > > > Changes in v2: > > > - New patch > > > --- > > > xen/include/asm-arm/lpae.h | 71 +++++++++++++++++++++----------------- > > > 1 file changed, 40 insertions(+), 31 deletions(-) > > > > > > diff --git a/xen/include/asm-arm/lpae.h b/xen/include/asm-arm/lpae.h > > > index 4fb9a40a4ca9..310f5225e056 100644 > > > --- a/xen/include/asm-arm/lpae.h > > > +++ b/xen/include/asm-arm/lpae.h > > > @@ -159,6 +159,17 @@ static inline bool lpae_is_superpage(lpae_t pte, > > > unsigned int level) > > > #define lpae_get_mfn(pte) (_mfn((pte).walk.base)) > > > #define lpae_set_mfn(pte, mfn) ((pte).walk.base = mfn_x(mfn)) > > > +/* Generate an array @var containing the offset for each level from > > > @addr */ > > > +#define DECLARE_OFFSETS(var, addr) \ > > > + const unsigned int var[4] = { \ > > > + zeroeth_table_offset(addr), \ > > > + first_table_offset(addr), \ > > > + second_table_offset(addr), \ > > > + third_table_offset(addr) \ > > > + } > > > + > > > +#endif /* __ASSEMBLY__ */ > > > + > > > /* > > > * AArch64 supports pages with different sizes (4K, 16K, and 64K). > > > * Provide a set of generic helpers that will compute various > > > @@ -190,17 +201,6 @@ static inline bool lpae_is_superpage(lpae_t pte, > > > unsigned int level) > > > #define LPAE_TABLE_INDEX_GS(gs, lvl, addr) \ > > > (((addr) >> LEVEL_SHIFT_GS(gs, lvl)) & LPAE_ENTRY_MASK_GS(gs)) > > > -/* Generate an array @var containing the offset for each level from > > > @addr */ > > > -#define DECLARE_OFFSETS(var, addr) \ > > > - const unsigned int var[4] = { \ > > > - zeroeth_table_offset(addr), \ > > > - first_table_offset(addr), \ > > > - second_table_offset(addr), \ > > > - third_table_offset(addr) \ > > > - } > > > - > > > -#endif /* __ASSEMBLY__ */ > > > - > > > /* > > > * These numbers add up to a 48-bit input address space. > > > * > > > @@ -211,26 +211,35 @@ static inline bool lpae_is_superpage(lpae_t pte, > > > unsigned int level) > > > * therefore 39-bits are sufficient. > > > */ > > > -#define LPAE_SHIFT 9 > > > -#define LPAE_ENTRIES (_AC(1,U) << LPAE_SHIFT) > > > -#define LPAE_ENTRY_MASK (LPAE_ENTRIES - 1) > > > - > > > -#define THIRD_SHIFT (PAGE_SHIFT) > > > -#define THIRD_ORDER (THIRD_SHIFT - PAGE_SHIFT) > > > -#define THIRD_SIZE (_AT(paddr_t, 1) << THIRD_SHIFT) > > > -#define THIRD_MASK (~(THIRD_SIZE - 1)) > > > -#define SECOND_SHIFT (THIRD_SHIFT + LPAE_SHIFT) > > > -#define SECOND_ORDER (SECOND_SHIFT - PAGE_SHIFT) > > > -#define SECOND_SIZE (_AT(paddr_t, 1) << SECOND_SHIFT) > > > -#define SECOND_MASK (~(SECOND_SIZE - 1)) > > > -#define FIRST_SHIFT (SECOND_SHIFT + LPAE_SHIFT) > > > -#define FIRST_ORDER (FIRST_SHIFT - PAGE_SHIFT) > > > -#define FIRST_SIZE (_AT(paddr_t, 1) << FIRST_SHIFT) > > > -#define FIRST_MASK (~(FIRST_SIZE - 1)) > > > -#define ZEROETH_SHIFT (FIRST_SHIFT + LPAE_SHIFT) > > > -#define ZEROETH_ORDER (ZEROETH_SHIFT - PAGE_SHIFT) > > > -#define ZEROETH_SIZE (_AT(paddr_t, 1) << ZEROETH_SHIFT) > > > -#define ZEROETH_MASK (~(ZEROETH_SIZE - 1)) > > > > Should we add a one-line in-code comment saying that the definitions > > below are for 4KB pages? It is not immediately obvious any longer. > > Because they are not meant to be for 4KB pages. They are meant to be for Xen > page size. > > Today, it is always 4KB but I would like the Xen code to not rely on that. > > I can clarify it in an in-code comment. That would help I think > > > +#define LPAE_SHIFT LPAE_SHIFT_GS(PAGE_SHIFT) > > > +#define LPAE_ENTRIES LPAE_ENTRIES_GS(PAGE_SHIFT) > > > +#define LPAE_ENTRY_MASK LPAE_ENTRY_MASK_GS(PAGE_SHIFT) > > > > > > +#define LEVEL_SHIFT(lvl) LEVEL_SHIFT_GS(PAGE_SHIFT, lvl) > > > +#define LEVEL_ORDER(lvl) LEVEL_ORDER_GS(PAGE_SHIFT, lvl) > > > +#define LEVEL_SIZE(lvl) LEVEL_SIZE_GS(PAGE_SHIFT, lvl) > > > +#define LEVEL_MASK(lvl) (~(LEVEL_SIZE(lvl) - 1)) > > > > I would avoid adding these 4 macros. It would be OK if they were just > > used within this file but lpae.h is a header: they could end up be used > > anywhere in the xen/ code and they have a very generic name. My > > suggestion would be to skip them and just do: > > Those macros will be used in follow-up patches. They are pretty useful to > avoid introduce static array with the different information for each level. > > Would prefix them with XEN_ be better? Maybe. The concern I have is that there are multiple page granularities (4kb, 16kb, etc) and multiple page sizes (4kb, 2mb, etc). If I just see LEVEL_ORDER it is not immediately obvious what granularity and what size we are talking about. I think using a name that makes it clear that they are referring to Xen pages, currently 4kb, it would make sense. Or maybe a in-code comment would be sufficient. I don't have a great suggestion here so I'll leave it to you. I am also OK to keep them as is. > > #define THIRD_SHIFT LEVEL_SHIFT_GS(PAGE_SHIFT, 3) > > > > etc. > > > > > > > +/* Convenience aliases */ > > > +#define THIRD_SHIFT LEVEL_SHIFT(3) > > > +#define THIRD_ORDER LEVEL_ORDER(3) > > > +#define THIRD_SIZE LEVEL_SIZE(3) > > > +#define THIRD_MASK LEVEL_MASK(3) > > > + > > > +#define SECOND_SHIFT LEVEL_SHIFT(2) > > > +#define SECOND_ORDER LEVEL_ORDER(2) > > > +#define SECOND_SIZE LEVEL_SIZE(2) > > > +#define SECOND_MASK LEVEL_MASK(2) > > > + > > > +#define FIRST_SHIFT LEVEL_SHIFT(1) > > > +#define FIRST_ORDER LEVEL_ORDER(1) > > > +#define FIRST_SIZE LEVEL_SIZE(1) > > > +#define FIRST_MASK LEVEL_MASK(1) > > > + > > > +#define ZEROETH_SHIFT LEVEL_SHIFT(0) > > > +#define ZEROETH_ORDER LEVEL_ORDER(0) > > > +#define ZEROETH_SIZE LEVEL_SIZE(0) > > > +#define ZEROETH_MASK LEVEL_MASK(0) > > > /* Calculate the offsets into the pagetables for a given VA */ > > > #define zeroeth_linear_offset(va) ((va) >> ZEROETH_SHIFT) > > > -- > > > 2.17.1 > > > > > Cheers, > > -- > Julien Grall >