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,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 8B62CC43332 for ; Mon, 18 Jan 2021 10:07:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6B083221FF for ; Mon, 18 Jan 2021 10:07:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389497AbhARKE6 (ORCPT ); Mon, 18 Jan 2021 05:04:58 -0500 Received: from mail.kernel.org ([198.145.29.99]:37026 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388298AbhARJsk (ORCPT ); Mon, 18 Jan 2021 04:48:40 -0500 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 E068322AAC; Mon, 18 Jan 2021 09:46:07 +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 1l1R6s-008RhD-5m; Mon, 18 Jan 2021 09:46:06 +0000 From: Marc Zyngier To: linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, linux-kernel@vger.kernel.org Cc: Catalin Marinas , Will Deacon , Mark Rutland , David Brazdil , Alexandru Elisei , Ard Biesheuvel , Jing Zhang , Ajay Patil , Prasad Sodagudi , Srinivas Ramana , James Morse , Julien Thierry , Suzuki K Poulose , kernel-team@android.com Subject: [PATCH v4 09/21] arm64: cpufeature: Add global feature override facility Date: Mon, 18 Jan 2021 09:45:21 +0000 Message-Id: <20210118094533.2874082-10-maz@kernel.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20210118094533.2874082-1-maz@kernel.org> References: <20210118094533.2874082-1-maz@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-SA-Exim-Connect-IP: 62.31.163.78 X-SA-Exim-Rcpt-To: 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, dbrazdil@google.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 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Add a facility to globally override a feature, no matter what the HW says. Yes, this sounds dangerous, but we do respect the "safe" value for a given feature. This doesn't mean the user doesn't need to know what they are doing. Nothing uses this yet, so we are pretty safe. For now. Signed-off-by: Marc Zyngier --- arch/arm64/include/asm/cpufeature.h | 2 ++ arch/arm64/kernel/cpufeature.c | 44 +++++++++++++++++++++++++---- 2 files changed, 41 insertions(+), 5 deletions(-) diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h index 9a555809b89c..465d2cb63bfc 100644 --- a/arch/arm64/include/asm/cpufeature.h +++ b/arch/arm64/include/asm/cpufeature.h @@ -75,6 +75,8 @@ struct arm64_ftr_reg { u64 sys_val; u64 user_val; const struct arm64_ftr_bits *ftr_bits; + u64 *override_val; + u64 *override_mask; }; extern struct arm64_ftr_reg arm64_ftr_reg_ctrel0; diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index e99eddec0a46..aaa075c6f029 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -544,13 +544,17 @@ static const struct arm64_ftr_bits ftr_raz[] = { ARM64_FTR_END, }; -#define ARM64_FTR_REG(id, table) { \ - .sys_id = id, \ - .reg = &(struct arm64_ftr_reg){ \ - .name = #id, \ - .ftr_bits = &((table)[0]), \ +#define ARM64_FTR_REG_OVERRIDE(id, table, v, m) { \ + .sys_id = id, \ + .reg = &(struct arm64_ftr_reg){ \ + .name = #id, \ + .ftr_bits = &((table)[0]), \ + .override_val = v, \ + .override_mask = m, \ }} +#define ARM64_FTR_REG(id, table) ARM64_FTR_REG_OVERRIDE(id, table, NULL, NULL) + static const struct __ftr_reg_entry { u32 sys_id; struct arm64_ftr_reg *reg; @@ -760,6 +764,7 @@ static void __init init_cpu_ftr_reg(u32 sys_reg, u64 new) u64 strict_mask = ~0x0ULL; u64 user_mask = 0; u64 valid_mask = 0; + u64 override_val = 0, override_mask = 0; const struct arm64_ftr_bits *ftrp; struct arm64_ftr_reg *reg = get_arm64_ftr_reg(sys_reg); @@ -767,9 +772,38 @@ static void __init init_cpu_ftr_reg(u32 sys_reg, u64 new) if (!reg) return; + if (reg->override_mask && reg->override_val) { + override_mask = *reg->override_mask; + override_val = *reg->override_val; + } + for (ftrp = reg->ftr_bits; ftrp->width; ftrp++) { u64 ftr_mask = arm64_ftr_mask(ftrp); s64 ftr_new = arm64_ftr_value(ftrp, new); + s64 ftr_ovr = arm64_ftr_value(ftrp, override_val); + + if ((ftr_mask & override_mask) == ftr_mask) { + s64 tmp = arm64_ftr_safe_value(ftrp, ftr_ovr, ftr_new); + char *str = NULL; + + if (ftr_ovr != tmp) { + /* Unsafe, remove the override */ + *reg->override_mask &= ~ftr_mask; + *reg->override_val &= ~ftr_mask; + tmp = ftr_ovr; + str = "ignoring override"; + } else if (ftr_new != tmp) { + /* Override was valid */ + ftr_new = tmp; + str = "forced"; + } + + if (str) + pr_warn("%s[%d:%d]: %s to %llx\n", + reg->name, + ftrp->shift + ftrp->width - 1, + ftrp->shift, str, tmp); + } val = arm64_ftr_set_value(ftrp, val, ftr_new); -- 2.29.2