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=-14.0 required=3.0 tests=BAYES_00,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 9FBF6C433DB for ; Sun, 24 Jan 2021 18:44:20 +0000 (UTC) Received: from mm01.cs.columbia.edu (mm01.cs.columbia.edu [128.59.11.253]) by mail.kernel.org (Postfix) with ESMTP id 118E622D03 for ; Sun, 24 Jan 2021 18:44:19 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 118E622D03 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvmarm-bounces@lists.cs.columbia.edu Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 8BD184B33A; Sun, 24 Jan 2021 13:44:19 -0500 (EST) X-Virus-Scanned: at lists.cs.columbia.edu Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id DSbD8dx3esdW; Sun, 24 Jan 2021 13:44:17 -0500 (EST) Received: from mm01.cs.columbia.edu (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 990E14B3F4; Sun, 24 Jan 2021 13:44:17 -0500 (EST) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 2A4C84B3C6 for ; Sun, 24 Jan 2021 13:44:17 -0500 (EST) X-Virus-Scanned: at lists.cs.columbia.edu Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 7M7cqewB40qD for ; Sun, 24 Jan 2021 13:44:16 -0500 (EST) Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by mm01.cs.columbia.edu (Postfix) with ESMTPS id 0601A4B3BD for ; Sun, 24 Jan 2021 13:44:16 -0500 (EST) Received: from disco-boy.misterjones.org (disco-boy.misterjones.org [51.254.78.96]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id E98CE222BB; Sun, 24 Jan 2021 18:44:14 +0000 (UTC) Received: from 78.163-31-62.static.virginmediabusiness.co.uk ([62.31.163.78] helo=wait-a-minute.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94) (envelope-from ) id 1l3kMu-009lbm-U9; Sun, 24 Jan 2021 18:44:13 +0000 Date: Sun, 24 Jan 2021 18:44:11 +0000 Message-ID: <87sg6qjhtw.wl-maz@kernel.org> From: Marc Zyngier To: David Brazdil Subject: Re: [PATCH v4 04/21] arm64: Provide an 'upgrade to VHE' stub hypercall In-Reply-To: <20210118112516.6a7lnrtbjvey4iiv@google.com> References: <20210118094533.2874082-1-maz@kernel.org> <20210118094533.2874082-5-maz@kernel.org> <20210118112516.6a7lnrtbjvey4iiv@google.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") X-SA-Exim-Connect-IP: 62.31.163.78 X-SA-Exim-Rcpt-To: dbrazdil@google.com, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, linux-kernel@vger.kernel.org, catalin.marinas@arm.com, will@kernel.org, mark.rutland@arm.com, alexandru.elisei@arm.com, ardb@kernel.org, jingzhangos@google.com, pajay@qti.qualcomm.com, psodagud@codeaurora.org, sramana@codeaurora.org, james.morse@arm.com, julien.thierry.kdev@gmail.com, suzuki.poulose@arm.com, kernel-team@android.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Cc: kernel-team@android.com, Srinivas Ramana , Catalin Marinas , linux-kernel@vger.kernel.org, Ard Biesheuvel , Ajay Patil , Prasad Sodagudi , Will Deacon , kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org X-BeenThere: kvmarm@lists.cs.columbia.edu X-Mailman-Version: 2.1.14 Precedence: list List-Id: Where KVM/ARM decisions are made List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu On Mon, 18 Jan 2021 11:25:16 +0000, David Brazdil wrote: > > On Mon, Jan 18, 2021 at 09:45:16AM +0000, Marc Zyngier wrote: > > As we are about to change the way a VHE system boots, let's > > provide the core helper, in the form of a stub hypercall that > > enables VHE and replicates the full EL1 context at EL2, thanks > > to EL1 and VHE-EL2 being extremely similar. > > > > On exception return, the kernel carries on at EL2. Fancy! > > > > Nothing calls this new hypercall yet, so no functional change. > > > > Signed-off-by: Marc Zyngier > > --- > > arch/arm64/include/asm/virt.h | 7 +++- > > arch/arm64/kernel/hyp-stub.S | 67 +++++++++++++++++++++++++++++++++-- > > 2 files changed, 71 insertions(+), 3 deletions(-) > > > > diff --git a/arch/arm64/include/asm/virt.h b/arch/arm64/include/asm/virt.h > > index ee6a48df89d9..7379f35ae2c6 100644 > > --- a/arch/arm64/include/asm/virt.h > > +++ b/arch/arm64/include/asm/virt.h > > @@ -35,8 +35,13 @@ > > */ > > #define HVC_RESET_VECTORS 2 > > > > +/* > > + * HVC_VHE_RESTART - Upgrade the CPU from EL1 to EL2, if possible > > + */ > > +#define HVC_VHE_RESTART 3 > > + > > /* Max number of HYP stub hypercalls */ > > -#define HVC_STUB_HCALL_NR 3 > > +#define HVC_STUB_HCALL_NR 4 > > > > /* Error returned when an invalid stub number is passed into x0 */ > > #define HVC_STUB_ERR 0xbadca11 > > diff --git a/arch/arm64/kernel/hyp-stub.S b/arch/arm64/kernel/hyp-stub.S > > index 160f5881a0b7..fb12398b5c28 100644 > > --- a/arch/arm64/kernel/hyp-stub.S > > +++ b/arch/arm64/kernel/hyp-stub.S > > @@ -8,9 +8,9 @@ > > > > #include > > #include > > -#include > > > > #include > > +#include > > #include > > #include > > #include > > @@ -47,10 +47,13 @@ SYM_CODE_END(__hyp_stub_vectors) > > > > SYM_CODE_START_LOCAL(el1_sync) > > cmp x0, #HVC_SET_VECTORS > > - b.ne 2f > > + b.ne 1f > > msr vbar_el2, x1 > > b 9f > > > > +1: cmp x0, #HVC_VHE_RESTART > > + b.eq mutate_to_vhe > > + > > 2: cmp x0, #HVC_SOFT_RESTART > > b.ne 3f > > mov x0, x2 > > @@ -70,6 +73,66 @@ SYM_CODE_START_LOCAL(el1_sync) > > eret > > SYM_CODE_END(el1_sync) > > > > +// nVHE? No way! Give me the real thing! > > +SYM_CODE_START_LOCAL(mutate_to_vhe) > > + // Sanity check: MMU *must* be off > > + mrs x0, sctlr_el2 > > + tbnz x0, #0, 1f > > + > > + // Needs to be VHE capable, obviously > > + mrs x0, id_aa64mmfr1_el1 > > + ubfx x0, x0, #ID_AA64MMFR1_VHE_SHIFT, #4 > > + cbz x0, 1f > > nit: There is a HVC_STUB_ERR that you could return if these sanity > checks fail. The documentation also states that it should be > returned on error. Good point. I've now added it, but how the error can be handled is still up in the air. For now, I've decided to let the kernel continue its (probably doomed) course. Thanks, M. -- Without deviation from the norm, progress is not possible. _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm