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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 42E93C433EF for ; Wed, 24 Nov 2021 23:36:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234080AbhKXXju (ORCPT ); Wed, 24 Nov 2021 18:39:50 -0500 Received: from mail.kernel.org ([198.145.29.99]:37266 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229799AbhKXXjn (ORCPT ); Wed, 24 Nov 2021 18:39:43 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 1D9F26108F; Wed, 24 Nov 2021 23:36:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1637796993; bh=CzDNbSFExR/OH7jKVlVsAtdlJOBl3QPTlsD27TWT+pA=; h=Date:From:To:cc:Subject:In-Reply-To:References:From; b=QaEyEMghFdE0vlspvMHAPD4NxBRW8ljDsQ4hZX6FqNQla4SD5G5cC5Or+18iNn4T4 5NPmAiA4pAuVlaeRyJwOgvIaiJEYNFeoZ3R1HWT6iL19itCxsAp2TPqF6QbMOBwrZ9 b/isS1rmlFO5uJxrLB6Y3g3715c83xeTaNSkpdjULnCnGTr+8XaUcyi22kcgOHvlRG 7IVymbC1xz+OlRXqpujYKuGfQia/X/IL+y8QX0KQ5XhRVCsgVZDSEJewW2BlD7/2+q Wo9JeTOkzl91GjZQzaDC44NBa1hUrbelktaVs+tUPSRa7LTXnKDkcE2Y7M4sjUD8fl wP4wpxMcrxtNg== Date: Wed, 24 Nov 2021 15:36:31 -0800 (PST) From: Stefano Stabellini X-X-Sender: sstabellini@ubuntu-linux-20-04-desktop To: Oleksandr Tyshchenko cc: xen-devel@lists.xenproject.org, linux-kernel@vger.kernel.org, Oleksandr Tyshchenko , Boris Ostrovsky , Juergen Gross , Stefano Stabellini , Julien Grall Subject: Re: [PATCH V3 3/6] xen/balloon: Bring alloc(free)_xenballooned_pages helpers back In-Reply-To: <1637787223-21129-4-git-send-email-olekstysh@gmail.com> Message-ID: References: <1637787223-21129-1-git-send-email-olekstysh@gmail.com> <1637787223-21129-4-git-send-email-olekstysh@gmail.com> User-Agent: Alpine 2.22 (DEB 394 2020-01-19) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 24 Nov 2021, Oleksandr Tyshchenko wrote: > From: Oleksandr Tyshchenko > > This patch rolls back some of the changes introduced by commit > 121f2faca2c0a "xen/balloon: rename alloc/free_xenballooned_pages" > in order to make possible to still allocate xenballooned pages > if CONFIG_XEN_UNPOPULATED_ALLOC is enabled. > > On Arm the unpopulated pages will be allocated on top of extended > regions provided by Xen via device-tree (the subsequent patches > will add required bits to support unpopulated-alloc feature on Arm). > The problem is that extended regions feature has been introduced > into Xen quite recently (during 4.16 release cycle). So this > effectively means that Linux must only use unpopulated-alloc on Arm > if it is running on "new Xen" which advertises these regions. > But, it will only be known after parsing the "hypervisor" node > at boot time, so before doing that we cannot assume anything. > > In order to keep working if CONFIG_XEN_UNPOPULATED_ALLOC is enabled > and the extended regions are not advertised (Linux is running on > "old Xen", etc) we need the fallback to alloc_xenballooned_pages(). > > This way we wouldn't reduce the amount of memory usable (wasting > RAM pages) for any of the external mappings anymore (and eliminate > XSA-300) with "new Xen", but would be still functional ballooning > out RAM pages with "old Xen". > > Also rename alloc(free)_xenballooned_pages to xen_alloc(free)_ballooned_pages > and make xen_alloc(free)_unpopulated_pages static inline in xen.h > if CONFIG_XEN_UNPOPULATED_ALLOC is disabled. > > Signed-off-by: Oleksandr Tyshchenko > Reviewed-by: Stefano Stabellini > --- > @Stefano, I decided to retain your R-b after making a minor > change (make xen_alloc(free)_unpopulated_pages static inline > in xen.h if CONFIG_XEN_UNPOPULATED_ALLOC is disabled). > Please let me know if you think otherwise. That's fine > Changes V2 -> V3: > - new patch > --- > drivers/xen/balloon.c | 20 +++++++++----------- > include/xen/balloon.h | 3 +++ > include/xen/xen.h | 14 ++++++++++++++ > 3 files changed, 26 insertions(+), 11 deletions(-) > > diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c > index ba2ea11..a2c4fc49 100644 > --- a/drivers/xen/balloon.c > +++ b/drivers/xen/balloon.c > @@ -581,7 +581,6 @@ void balloon_set_new_target(unsigned long target) > } > EXPORT_SYMBOL_GPL(balloon_set_new_target); > > -#ifndef CONFIG_XEN_UNPOPULATED_ALLOC > static int add_ballooned_pages(unsigned int nr_pages) > { > enum bp_state st; > @@ -610,12 +609,12 @@ static int add_ballooned_pages(unsigned int nr_pages) > } > > /** > - * xen_alloc_unpopulated_pages - get pages that have been ballooned out > + * xen_alloc_ballooned_pages - get pages that have been ballooned out > * @nr_pages: Number of pages to get > * @pages: pages returned > * @return 0 on success, error otherwise > */ > -int xen_alloc_unpopulated_pages(unsigned int nr_pages, struct page **pages) > +int xen_alloc_ballooned_pages(unsigned int nr_pages, struct page **pages) > { > unsigned int pgno = 0; > struct page *page; > @@ -652,23 +651,23 @@ int xen_alloc_unpopulated_pages(unsigned int nr_pages, struct page **pages) > return 0; > out_undo: > mutex_unlock(&balloon_mutex); > - xen_free_unpopulated_pages(pgno, pages); > + xen_free_ballooned_pages(pgno, pages); > /* > - * NB: free_xenballooned_pages will only subtract pgno pages, but since > + * NB: xen_free_ballooned_pages will only subtract pgno pages, but since > * target_unpopulated is incremented with nr_pages at the start we need > * to remove the remaining ones also, or accounting will be screwed. > */ > balloon_stats.target_unpopulated -= nr_pages - pgno; > return ret; > } > -EXPORT_SYMBOL(xen_alloc_unpopulated_pages); > +EXPORT_SYMBOL(xen_alloc_ballooned_pages); > > /** > - * xen_free_unpopulated_pages - return pages retrieved with get_ballooned_pages > + * xen_free_ballooned_pages - return pages retrieved with get_ballooned_pages > * @nr_pages: Number of pages > * @pages: pages to return > */ > -void xen_free_unpopulated_pages(unsigned int nr_pages, struct page **pages) > +void xen_free_ballooned_pages(unsigned int nr_pages, struct page **pages) > { > unsigned int i; > > @@ -687,9 +686,9 @@ void xen_free_unpopulated_pages(unsigned int nr_pages, struct page **pages) > > mutex_unlock(&balloon_mutex); > } > -EXPORT_SYMBOL(xen_free_unpopulated_pages); > +EXPORT_SYMBOL(xen_free_ballooned_pages); > > -#if defined(CONFIG_XEN_PV) > +#if defined(CONFIG_XEN_PV) && !defined(CONFIG_XEN_UNPOPULATED_ALLOC) > static void __init balloon_add_region(unsigned long start_pfn, > unsigned long pages) > { > @@ -712,7 +711,6 @@ static void __init balloon_add_region(unsigned long start_pfn, > balloon_stats.total_pages += extra_pfn_end - start_pfn; > } > #endif > -#endif > > static int __init balloon_init(void) > { > diff --git a/include/xen/balloon.h b/include/xen/balloon.h > index e93d4f0..f78a6cc 100644 > --- a/include/xen/balloon.h > +++ b/include/xen/balloon.h > @@ -26,6 +26,9 @@ extern struct balloon_stats balloon_stats; > > void balloon_set_new_target(unsigned long target); > > +int xen_alloc_ballooned_pages(unsigned int nr_pages, struct page **pages); > +void xen_free_ballooned_pages(unsigned int nr_pages, struct page **pages); > + > #ifdef CONFIG_XEN_BALLOON > void xen_balloon_init(void); > #else > diff --git a/include/xen/xen.h b/include/xen/xen.h > index 9f031b5..86c5b37 100644 > --- a/include/xen/xen.h > +++ b/include/xen/xen.h > @@ -52,7 +52,21 @@ bool xen_biovec_phys_mergeable(const struct bio_vec *vec1, > extern u64 xen_saved_max_mem_size; > #endif > > +#ifdef CONFIG_XEN_UNPOPULATED_ALLOC > int xen_alloc_unpopulated_pages(unsigned int nr_pages, struct page **pages); > void xen_free_unpopulated_pages(unsigned int nr_pages, struct page **pages); > +#else > +#include > +static inline int xen_alloc_unpopulated_pages(unsigned int nr_pages, > + struct page **pages) > +{ > + return xen_alloc_ballooned_pages(nr_pages, pages); > +} > +static inline void xen_free_unpopulated_pages(unsigned int nr_pages, > + struct page **pages) > +{ > + xen_free_ballooned_pages(nr_pages, pages); > +} > +#endif > > #endif /* _XEN_XEN_H */ > -- > 2.7.4 >