From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alex Bennée Date: Thu, 01 Aug 2024 10:20:59 +0100 Subject: [PATCH v12 05/84] KVM: Add kvm_release_page_unused() API to put pages that KVM never consumes In-Reply-To: <20240726235234.228822-6-seanjc@google.com> (Sean Christopherson's message of "Fri, 26 Jul 2024 16:51:14 -0700") References: <20240726235234.228822-1-seanjc@google.com> <20240726235234.228822-6-seanjc@google.com> Message-ID: <87wml0egzo.fsf@draig.linaro.org> List-Id: To: kvm-riscv@lists.infradead.org MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sean Christopherson writes: > Add an API to release an unused page, i.e. to put a page without marking > it accessed or dirty. The API will be used when KVM faults-in a page but > bails before installing the guest mapping (and other similar flows). > > Signed-off-by: Sean Christopherson > --- > include/linux/kvm_host.h | 9 +++++++++ > 1 file changed, 9 insertions(+) > > diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h > index 3d9617d1de41..c5d39a337aa3 100644 > --- a/include/linux/kvm_host.h > +++ b/include/linux/kvm_host.h > @@ -1201,6 +1201,15 @@ unsigned long gfn_to_hva_prot(struct kvm *kvm, gfn_t gfn, bool *writable); > unsigned long gfn_to_hva_memslot(struct kvm_memory_slot *slot, gfn_t gfn); > unsigned long gfn_to_hva_memslot_prot(struct kvm_memory_slot *slot, gfn_t gfn, > bool *writable); > + > +static inline void kvm_release_page_unused(struct page *page) > +{ > + if (!page) > + return; > + > + put_page(page); > +} I guess it's unfamiliarity with the mm layout but I was trying to find where the get_pages come from to see the full pattern of allocate and return. I guess somewhere in the depths of hva_to_pfn() from hva_to_pfn_retry()? I think the indirection of the page walking confuses me ;-) Anyway the API seems reasonable enough given the other kvm_release_ functions. 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charset=utf-8 Content-Transfer-Encoding: quoted-printable Sean Christopherson writes: > Add an API to release an unused page, i.e. to put a page without marking > it accessed or dirty. The API will be used when KVM faults-in a page but > bails before installing the guest mapping (and other similar flows). > > Signed-off-by: Sean Christopherson > --- > include/linux/kvm_host.h | 9 +++++++++ > 1 file changed, 9 insertions(+) > > diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h > index 3d9617d1de41..c5d39a337aa3 100644 > --- a/include/linux/kvm_host.h > +++ b/include/linux/kvm_host.h > @@ -1201,6 +1201,15 @@ unsigned long gfn_to_hva_prot(struct kvm *kvm, gfn= _t gfn, bool *writable); > unsigned long gfn_to_hva_memslot(struct kvm_memory_slot *slot, gfn_t gfn= ); > unsigned long gfn_to_hva_memslot_prot(struct kvm_memory_slot *slot, gfn_= t gfn, > bool *writable); > + > +static inline void kvm_release_page_unused(struct page *page) > +{ > + if (!page) > + return; > + > + put_page(page); > +} I guess it's unfamiliarity with the mm layout but I was trying to find where the get_pages come from to see the full pattern of allocate and return. I guess somewhere in the depths of hva_to_pfn() from hva_to_pfn_retry()? I think the indirection of the page walking confuses me ;-) Anyway the API seems reasonable enough given the other kvm_release_ functions. Reviewed-by: Alex Benn=C3=A9e --=20 Alex Benn=C3=A9e Virtualisation Tech Lead @ Linaro 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 4908DC3DA64 for ; Thu, 1 Aug 2024 09:21:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:Message-ID:Date:References :In-Reply-To:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=bybJ7aB7bXMFEUvhU7XgRDR4r+eY0G7BIfavP5MLjvI=; 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Thu, 01 Aug 2024 02:21:01 -0700 (PDT) Received: from draig (localhost [IPv6:::1]) by draig.lan (Postfix) with ESMTP id 51C785F80C; Thu, 1 Aug 2024 10:20:59 +0100 (BST) From: =?utf-8?Q?Alex_Benn=C3=A9e?= To: Sean Christopherson Subject: Re: [PATCH v12 05/84] KVM: Add kvm_release_page_unused() API to put pages that KVM never consumes In-Reply-To: <20240726235234.228822-6-seanjc@google.com> (Sean Christopherson's message of "Fri, 26 Jul 2024 16:51:14 -0700") References: <20240726235234.228822-1-seanjc@google.com> <20240726235234.228822-6-seanjc@google.com> Date: Thu, 01 Aug 2024 10:20:59 +0100 Message-ID: <87wml0egzo.fsf@draig.linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, David Matlack , linux-riscv@lists.infradead.org, Claudio Imbrenda , Janosch Frank , Marc Zyngier , Huacai Chen , Christian Borntraeger , Albert Ou , Bibo Mao , loongarch@lists.linux.dev, Paul Walmsley , kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-mips@vger.kernel.org, Oliver Upton , Palmer Dabbelt , David Stevens , kvm-riscv@lists.infradead.org, Anup Patel , Paolo Bonzini , Tianrui Zhao , linuxppc-dev@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Sean Christopherson writes: > Add an API to release an unused page, i.e. to put a page without marking > it accessed or dirty. The API will be used when KVM faults-in a page but > bails before installing the guest mapping (and other similar flows). > > Signed-off-by: Sean Christopherson > --- > include/linux/kvm_host.h | 9 +++++++++ > 1 file changed, 9 insertions(+) > > diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h > index 3d9617d1de41..c5d39a337aa3 100644 > --- a/include/linux/kvm_host.h > +++ b/include/linux/kvm_host.h > @@ -1201,6 +1201,15 @@ unsigned long gfn_to_hva_prot(struct kvm *kvm, gfn= _t gfn, bool *writable); > unsigned long gfn_to_hva_memslot(struct kvm_memory_slot *slot, gfn_t gfn= ); > unsigned long gfn_to_hva_memslot_prot(struct kvm_memory_slot *slot, gfn_= t gfn, > bool *writable); > + > +static inline void kvm_release_page_unused(struct page *page) > +{ > + if (!page) > + return; > + > + put_page(page); > +} I guess it's unfamiliarity with the mm layout but I was trying to find where the get_pages come from to see the full pattern of allocate and return. I guess somewhere in the depths of hva_to_pfn() from hva_to_pfn_retry()? I think the indirection of the page walking confuses me ;-) Anyway the API seems reasonable enough given the other kvm_release_ functions. Reviewed-by: Alex Benn=C3=A9e --=20 Alex Benn=C3=A9e Virtualisation Tech Lead @ Linaro