From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BA47B176FCE; Wed, 10 Jul 2024 08:51:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720601487; cv=none; b=s2Y+K4oBj6A11nVBSNQsdl0XFZfwZ83DeJn68Azt5DuyLYkJk5eZbqt0PokGulp9iH9nb2+ZS6iQmnhF0dv9zP5lpBIl0/zBv+7BBExccT2m9phj7mTbUrVU0/lIPJChw0C07aZSDE7GGVoNYgPksYWdjfmoZyFJT3jG9hZeFC0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720601487; c=relaxed/simple; bh=dnAQkPxYtxbaIwh+/jYCb8bb1Ou4HEWUt8N3rsbRkVI=; h=Date:Message-ID:From:To:Cc:Subject:In-Reply-To:References: MIME-Version:Content-Type; b=C/IWcxME47XY3ko4Mgi7IhpWH7yhT9b0VNJSrGBM/jR5IQbOAUFGoMxHBDjR1PcM6MdOjIZfGRhyO8pejpnRkkxifwyse8DYZNuvSby5lc6iTeJr56+Ci14VCdzXMLNZEK4ROhxTTpQs+6SN7iOvFLt9RsJC7PMJKN4JuFa6q+w= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=llpc7gc1; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="llpc7gc1" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 45D82C32781; Wed, 10 Jul 2024 08:51:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1720601487; bh=dnAQkPxYtxbaIwh+/jYCb8bb1Ou4HEWUt8N3rsbRkVI=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=llpc7gc1DVf6Ls9Mp8WWZKfbbl4lDFsoGRMl8ruvGncvzGLFdXsVl7bj404rPtlbF 3fUzoHX/fdmFy0ZkeER+uxGNItYekQpT2s0flHwrode59lobwdq4vrEqcUsa3FN57k mEFOz1pr5wQ8+n7WAO8rF/LfRIFbWmaOfP7HTJgezQlvkHVpLlfaPLD7AqUg/MtgEc Ocy7fuK5R1DA8z1G6EIe5YFVVy3HFbtCPZoK72fi1XxwzQ+5utbV0gBfDnf3IFEvDi Qz1DjryY9hls1Txh6KMER80o/NvwWA8CwrJpdO39opqnsbwePaiQPRDg4qFzckc+1+ ONxFn5h+z0JUg== Received: from sofa.misterjones.org ([185.219.108.64] helo=goblin-girl.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.95) (envelope-from ) id 1sRT2q-00BA9w-S0; Wed, 10 Jul 2024 09:51:24 +0100 Date: Wed, 10 Jul 2024 09:51:24 +0100 Message-ID: <86zfqp3a0j.wl-maz@kernel.org> From: Marc Zyngier To: Tangnianyao Cc: , , , James Morse , Suzuki K Poulose , Oliver Upton , Zenghui Yu , Quentin Perret , Will Deacon , Fuad Tabba , "guoyang (C)" Subject: Re: [PATCH v3 00/17] KVM: arm64: Allow using VHE in the nVHE hypervisor In-Reply-To: <5ab07210-ad44-616c-cd15-0ac954453fcf@huawei.com> References: <20230609162200.2024064-1-maz@kernel.org> <5ab07210-ad44-616c-cd15-0ac954453fcf@huawei.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/29.3 (aarch64-unknown-linux-gnu) MULE/6.0 (HANACHIRUSATO) Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=US-ASCII X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: tangnianyao@huawei.com, kvmarm@lists.linux.dev, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, james.morse@arm.com, suzuki.poulose@arm.com, oliver.upton@linux.dev, yuzenghui@huawei.com, qperret@google.com, will@kernel.org, tabba@google.com, guoyang2@huawei.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false On Wed, 10 Jul 2024 07:45:52 +0100, Tangnianyao wrote: > > Hi Marz, > > I'm trying to learn pKVM and have a question. > > Why pKVM developed on E2H=0 firstly? It tried to avoid host access > guest memory with stage2 translation, and it seems not necessarily > rely on HCR_EL2.E2H=0. Because we don't want to leave ARMv8.0 systems behind. They are still a large portion of the arm64 HW running Linux. > Is hVHE an alternative plan of pKVM ? To allow pKVM run on E2H res1 system ? Supporting E2H RES1 implementations is indeed one of the motivations. But there is a lot more to it, such as being able to use the two TTBRs to perform address space isolation inside the hypervisor. I presented this[1] at KVM Forum two years ago, which explains what we could do (some of which is already in progress). M. [1] https://static.sched.com/hosted_files/kvmforum2022/b4/NYSM-NYD-KVM-2022.pdf -- Without deviation from the norm, progress is not possible.