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Wed, 24 Aug 2022 15:25:06 +0100 Date: Wed, 24 Aug 2022 15:24:57 +0100 Message-ID: <87zgftra6e.wl-maz@kernel.org> From: Marc Zyngier To: Ryan Roberts Cc: Yosry Ahmed , Tejun Heo , Johannes Weiner , Zefan Li , James Morse , Alexandru Elisei , Suzuki K Poulose , Paolo Bonzini , Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Andrew Morton , Michal Hocko , Roman Gushchin , Shakeel Butt , Oliver Upton , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Huang@google.com, Shaoqin , linux-mm@kvack.org, cgroups@vger.kernel.org, kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org, nd@arm.com Subject: Re: [PATCH v7 4/4] KVM: arm64/mmu: count KVM s2 mmu usage in secondary pagetable stats In-Reply-To: <319904e0-3722-8ab1-cf74-491b9c32e23b@arm.com> References: <20220823004639.2387269-1-yosryahmed@google.com> <20220823004639.2387269-5-yosryahmed@google.com> <319904e0-3722-8ab1-cf74-491b9c32e23b@arm.com> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/27.1 (x86_64-pc-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; 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dkim=pass header.d=kernel.org header.s=k20201202 header.b=RlOFCFyO; spf=pass (imf14.hostedemail.com: domain of maz@kernel.org designates 145.40.68.75 as permitted sender) smtp.mailfrom=maz@kernel.org; dmarc=pass (policy=none) header.from=kernel.org X-HE-Tag: 1661351113-574981 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, 24 Aug 2022 14:43:43 +0100, Ryan Roberts wrote: > > > Count the pages used by KVM in arm64 for stage2 mmu in memory stats > > under secondary pagetable stats (e.g. "SecPageTables" in /proc/meminfo) > > to give better visibility into the memory consumption of KVM mmu in a > > similar way to how normal user page tables are accounted. > > > > Signed-off-by: Yosry Ahmed > > Reviewed-by: Oliver Upton > > Reviewed-by: Marc Zyngier > > --- > > I see that you are not including the memory reserved for the host > stage2 table when using protected KVM. Is this something worth adding? > (See arch/arm64/kvm/pkvm.c:kvm_hyp_reserve()). > > This reservation is done pretty early on in bootmem_init() so not sure > if this could cause some init ordering issues that might be tricky to > solve though. I also don't see what this buys us. This memory can't be reclaimed, and is not part of KVM's job for the purpose of running guests, which is what this series is about. If anything, it should be accounted separately. M. -- Without deviation from the norm, progress is not possible.