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=-17.0 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,URIBL_BLOCKED,USER_AGENT_GIT 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 135A7C433B4 for ; Thu, 8 Apr 2021 13:12:08 +0000 (UTC) Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (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 A61F561153 for ; Thu, 8 Apr 2021 13:12:07 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A61F561153 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=desiato.20200630; h=Sender:Content-Transfer-Encoding :Content-Type:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To:Message-Id:Date: 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=XEvXwK26dn5aAO14fxaY7Re8F/whZ6YdVCWNv6L0Ojg=; b=HaKFdNiIdpIIjiSouUwsyaKuD 9tlHttD6t8Fhe+GBEqRufXxOOkBXHOGnX+Qyom5IKdbHzb6SBIeaUHAfBC6Vqd7rKXpHkrUHHjkZV kHxhaJhukZgVipUKchLG1Puud6PNXqcUqagV2pY3OVJtKL1+dqMCVi51R6f+65EfgPqPjoWyUuP8Q R9P7Qkh/e2s6TF5QM+0ats8NxqVeDoO9nAafhUSxiNEjQm4B6w536wXhev66EaiH6LGOICBioEhcS Aj80UA4I62WCr4fCkdY+YLRUm/Sn2d1oUWK/Bi7HGjErpmSQ3BSCQaHHkFvJcSWjpShcy3V5/CnvI csQ0r3Tdg==; Received: from localhost ([::1] helo=desiato.infradead.org) by desiato.infradead.org with esmtp (Exim 4.94 #2 (Red Hat Linux)) id 1lUUQX-0084eQ-Ov; Thu, 08 Apr 2021 13:10:29 +0000 Received: from mail.kernel.org ([198.145.29.99]) by desiato.infradead.org with esmtps (Exim 4.94 #2 (Red Hat Linux)) id 1lUUQR-0084d6-LJ for linux-arm-kernel@lists.infradead.org; Thu, 08 Apr 2021 13:10:25 +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 C0FE46115B; Thu, 8 Apr 2021 13:10:21 +0000 (UTC) Received: from 78.163-31-62.static.virginmediabusiness.co.uk ([62.31.163.78] helo=why.lan) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94) (envelope-from ) id 1lUUQN-006JMB-TK; Thu, 08 Apr 2021 14:10:20 +0100 From: Marc Zyngier To: linux-arm-kernel@lists.infradead.org Cc: Hector Martin , Arnd Bergmann , Mark Rutland , Will Deacon , Catalin Marinas , kernel-team@android.com Subject: [PATCH v3 2/3] arm64: Cope with CPUs stuck in VHE mode Date: Thu, 8 Apr 2021 14:10:09 +0100 Message-Id: <20210408131010.1109027-3-maz@kernel.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20210408131010.1109027-1-maz@kernel.org> References: <20210408131010.1109027-1-maz@kernel.org> MIME-Version: 1.0 X-SA-Exim-Connect-IP: 62.31.163.78 X-SA-Exim-Rcpt-To: linux-arm-kernel@lists.infradead.org, marcan@marcan.st, arnd@kernel.org, mark.rutland@arm.com, will@kernel.org, catalin.marinas@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 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210408_141024_096793_453B12A6 X-CRM114-Status: GOOD ( 17.90 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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 It seems that the CPUs part of the SoC known as Apple M1 have the terrible habit of being stuck with HCR_EL2.E2H==1, in violation of the architecture. Try and work around this deplorable state of affairs by detecting the stuck bit early and short-circuit the nVHE dance. Additional filtering code ensures that attempts at switching to nVHE from the command-line are also ignored. It is still unknown whether there are many more such nuggets to be found... Reported-by: Hector Martin Acked-by: Will Deacon Signed-off-by: Marc Zyngier --- arch/arm64/kernel/head.S | 39 +++++++++++++++++++++++++++--- arch/arm64/kernel/hyp-stub.S | 8 +++--- arch/arm64/kernel/idreg-override.c | 13 +++++++++- 3 files changed, 52 insertions(+), 8 deletions(-) diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S index 840bda1869e9..96873dfa67fd 100644 --- a/arch/arm64/kernel/head.S +++ b/arch/arm64/kernel/head.S @@ -477,14 +477,13 @@ EXPORT_SYMBOL(kimage_vaddr) * booted in EL1 or EL2 respectively. */ SYM_FUNC_START(init_kernel_el) - mov_q x0, INIT_SCTLR_EL1_MMU_OFF - msr sctlr_el1, x0 - mrs x0, CurrentEL cmp x0, #CurrentEL_EL2 b.eq init_el2 SYM_INNER_LABEL(init_el1, SYM_L_LOCAL) + mov_q x0, INIT_SCTLR_EL1_MMU_OFF + msr sctlr_el1, x0 isb mov_q x0, INIT_PSTATE_EL1 msr spsr_el1, x0 @@ -504,9 +503,43 @@ SYM_INNER_LABEL(init_el2, SYM_L_LOCAL) msr vbar_el2, x0 isb + /* + * Fruity CPUs seem to have HCR_EL2.E2H set to RES1, + * making it impossible to start in nVHE mode. Is that + * compliant with the architecture? Absolutely not! + */ + mrs x0, hcr_el2 + and x0, x0, #HCR_E2H + cbz x0, 1f + + /* Switching to VHE requires a sane SCTLR_EL1 as a start */ + mov_q x0, INIT_SCTLR_EL1_MMU_OFF + msr_s SYS_SCTLR_EL12, x0 + + /* + * Force an eret into a helper "function", and let it return + * to our original caller... This makes sure that we have + * initialised the basic PSTATE state. + */ + mov x0, #INIT_PSTATE_EL2 + msr spsr_el1, x0 + adr x0, __cpu_stick_to_vhe + msr elr_el1, x0 + eret + +1: + mov_q x0, INIT_SCTLR_EL1_MMU_OFF + msr sctlr_el1, x0 + msr elr_el2, lr mov w0, #BOOT_CPU_MODE_EL2 eret + +__cpu_stick_to_vhe: + mov x0, #HVC_VHE_RESTART + hvc #0 + mov x0, #BOOT_CPU_MODE_EL2 + ret SYM_FUNC_END(init_kernel_el) /* diff --git a/arch/arm64/kernel/hyp-stub.S b/arch/arm64/kernel/hyp-stub.S index 5eccbd62fec8..9c9b4d8fc395 100644 --- a/arch/arm64/kernel/hyp-stub.S +++ b/arch/arm64/kernel/hyp-stub.S @@ -27,12 +27,12 @@ SYM_CODE_START(__hyp_stub_vectors) ventry el2_fiq_invalid // FIQ EL2t ventry el2_error_invalid // Error EL2t - ventry el2_sync_invalid // Synchronous EL2h + ventry elx_sync // Synchronous EL2h ventry el2_irq_invalid // IRQ EL2h ventry el2_fiq_invalid // FIQ EL2h ventry el2_error_invalid // Error EL2h - ventry el1_sync // Synchronous 64-bit EL1 + ventry elx_sync // Synchronous 64-bit EL1 ventry el1_irq_invalid // IRQ 64-bit EL1 ventry el1_fiq_invalid // FIQ 64-bit EL1 ventry el1_error_invalid // Error 64-bit EL1 @@ -45,7 +45,7 @@ SYM_CODE_END(__hyp_stub_vectors) .align 11 -SYM_CODE_START_LOCAL(el1_sync) +SYM_CODE_START_LOCAL(elx_sync) cmp x0, #HVC_SET_VECTORS b.ne 1f msr vbar_el2, x1 @@ -71,7 +71,7 @@ SYM_CODE_START_LOCAL(el1_sync) 9: mov x0, xzr eret -SYM_CODE_END(el1_sync) +SYM_CODE_END(elx_sync) // nVHE? No way! Give me the real thing! SYM_CODE_START_LOCAL(mutate_to_vhe) diff --git a/arch/arm64/kernel/idreg-override.c b/arch/arm64/kernel/idreg-override.c index be92fcd319a1..e628c8ce1ffe 100644 --- a/arch/arm64/kernel/idreg-override.c +++ b/arch/arm64/kernel/idreg-override.c @@ -29,11 +29,22 @@ struct ftr_set_desc { } fields[]; }; +static bool __init mmfr1_vh_filter(u64 val) +{ + /* + * If we ever reach this point while running VHE, we're + * guaranteed to be on one of these funky, VHE-stuck CPUs. If + * the user was trying to force nVHE on us, proceed with + * attitude adjustment. + */ + return !(is_kernel_in_hyp_mode() && val == 0); +} + static const struct ftr_set_desc mmfr1 __initconst = { .name = "id_aa64mmfr1", .override = &id_aa64mmfr1_override, .fields = { - { "vh", ID_AA64MMFR1_VHE_SHIFT }, + { "vh", ID_AA64MMFR1_VHE_SHIFT, mmfr1_vh_filter }, {} }, }; -- 2.29.2 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel