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=-14.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 5BE3BC433DB for ; Tue, 5 Jan 2021 21:05:48 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 16C2822D00 for ; Tue, 5 Jan 2021 21:05:48 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 16C2822D00 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To:Subject:To:From: Message-ID:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=TwQlMC+YtGKV2M2UXA0zenh07cI2HaP/dbsPCzVMlDE=; b=1Vp9loCTcTRrR/518V+yHiu+H f/zEQeVAx+YFGIdr6c96U6ZL68OdUgZKPg/FnjOChSCbnPNO525Ub43DMA5pFBvfP19tsTh1gqlem P0buTdo5NbdAQ3Uv1Ppwu+jVexfT0buMmYHSRD7GiyieXiyS6+Hg4Naab72nRKp0j2/HyteBO/0Cx F6pNMw97oefABOwCosCw++7P2oRTpgg/nj0ti7qXkZktvn7uKwlDQ72mkpW9K+aWmjvoTbEPLSm4U 6Thx7QucH/MLYW377MYFO+EaVjXPS3JI05YOOnyANOc4F2+1YLUB68Pb6aUQx/mHNUIjy17jsyHzp DD1Jq590Q==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kwtUX-00006b-64; Tue, 05 Jan 2021 21:03:45 +0000 Received: from mail.kernel.org ([198.145.29.99]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1kwtUU-00006E-9D for linux-arm-kernel@lists.infradead.org; Tue, 05 Jan 2021 21:03:43 +0000 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 F41F722D5A; Tue, 5 Jan 2021 21:03:40 +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 1kwtUQ-005Voo-Pe; Tue, 05 Jan 2021 21:03:39 +0000 Date: Tue, 05 Jan 2021 21:03:37 +0000 Message-ID: <87zh1njdue.wl-maz@kernel.org> From: Marc Zyngier To: Jing Zhang Subject: Re: [PATCH v2 04/17] arm64: Provide an 'upgrade to VHE' stub hypercall In-Reply-To: References: <20210104135011.2063104-1-maz@kernel.org> <20210104135011.2063104-5-maz@kernel.org> 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 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: jingzhangos@google.com, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kernel-team@android.com, catalin.marinas@arm.com, will@kernel.org, ardb@kernel.org X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210105_160342_463930_B600CDF6 X-CRM114-Status: GOOD ( 25.11 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kernel-team@android.com, Catalin Marinas , Ard Biesheuvel , Will Deacon , kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, 05 Jan 2021 20:35:35 +0000, Jing Zhang wrote: > > On Mon, Jan 4, 2021 at 7:50 AM 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 | 70 ++++++++++++++++++++++++++++++++++- > > 2 files changed, 74 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..6ffdc1f7778b 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 +47,16 @@ 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.ne 2f > > + mov x0, #HVC_SOFT_RESTART > > + adr x1, mutate_to_vhe > > + // fall through... > Does "br x1" work here instead of falling through into > HVC_SOFT_RESTART? Just curious about the reason for falling-through. Absolutely. This is the leftover from an initial (and pretty over-engineered) approach where the caller was using HVC_SOFT_RESTART with the address of mutate_to_vhe passed as the target. It was an interesting idea, but obtaining the PA for the function ended when the MMU is on created a separate, harder to maintain path. Cleanup time, I guess. Thanks, M. -- Without deviation from the norm, progress is not possible. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel