From patchwork Thu Oct 5 09:49:53 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mark Rutland X-Patchwork-Id: 13409926 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 3AAD4E8FDC3 for ; Thu, 5 Oct 2023 09:51:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; 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=9nujMjC4qXogUoEk4qu1K57NLrpXUdf/Ch/0yY7mo6Y=; b=EuZiZcjXBARxP7 r/ljhtkPQbJIHeRSVKwq1JbBokv+YJvxJZIO6m4V47KQ0dHPM5hhPTBKdLnfsJFWYy1cFzIBc7Pze iVHGSkwFi1nS13Kw3siZya/6Ysoi/xyIdz88M81RJMMmUmvY8Eh5nHsZqxmU6w2MpdKHqGNGGe0Gp nNHY8OUdL+wyR4xkH+pzaSkJ5Zy82SsHdGWdg69qRxyEjN39zq7zUooMjyzxavRQd5g+OPqQaWlQf Lec4Y7LQx1CoCLPAXPBEea/l/JalPSF7XLsLEJ74u316y7mD6Uxs6pl9d2SWBlGyH3fhtf2bMRZWA KVqcf/HLISkOrdXwdkuQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1qoL0f-001nbb-0G; Thu, 05 Oct 2023 09:51:09 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1qoL0b-001nZV-27 for linux-arm-kernel@lists.infradead.org; Thu, 05 Oct 2023 09:51:07 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id BD2CF152B; Thu, 5 Oct 2023 02:51:40 -0700 (PDT) Received: from lakrids.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id D8ACB3F5A1; Thu, 5 Oct 2023 02:50:59 -0700 (PDT) From: Mark Rutland To: linux-arm-kernel@lists.infradead.org Cc: ardb@kernel.org, bertrand.marquis@arm.com, boris.ostrovsky@oracle.com, broonie@kernel.org, catalin.marinas@arm.com, daniel.lezcano@linaro.org, james.morse@arm.com, jgross@suse.com, kristina.martsenko@arm.com, mark.rutland@arm.com, maz@kernel.org, oliver.upton@linux.dev, pcc@google.com, sstabellini@kernel.org, suzuki.poulose@arm.com, tglx@linutronix.de, vladimir.murzin@arm.com, will@kernel.org Subject: [PATCH v2 07/38] arm64: Fixup user features at boot time Date: Thu, 5 Oct 2023 10:49:53 +0100 Message-Id: <20231005095025.1872048-8-mark.rutland@arm.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20231005095025.1872048-1-mark.rutland@arm.com> References: <20231005095025.1872048-1-mark.rutland@arm.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20231005_025105_844211_738C0350 X-CRM114-Status: GOOD ( 17.34 ) 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: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org For ARM64_WORKAROUND_2658417, we use a cpu_enable() callback to hide the ID_AA64ISAR1_EL1.BF16 ID register field. This is a little awkward as CPUs may attempt to apply the workaround concurrently, requiring that we protect the bulk of the callback with a raw_spinlock, and requiring some pointless work every time a CPU is subsequently hotplugged in. This patch makes this a little simpler by handling the masking once at boot time. A new user_feature_fixup() function is called at the start of setup_user_features() to mask the feature, matching the style of elf_hwcap_fixup(). The ARM64_WORKAROUND_2658417 cpucap is added to cpucap_is_possible() so that code can be elided entirely when this is not possible. Note that the ARM64_WORKAROUND_2658417 capability is matched with ERRATA_MIDR_RANGE(), which implicitly gives the capability a ARM64_CPUCAP_LOCAL_CPU_ERRATUM type, which forbids the late onlining of a CPU with the erratum if the erratum was not present at boot time. Therefore this patch doesn't change the behaviour for late onlining. Signed-off-by: Mark Rutland Cc: Catalin Marinas Cc: James Morse Cc: Mark Brown Cc: Suzuki K Poulose Cc: Will Deacon --- arch/arm64/include/asm/cpucaps.h | 2 ++ arch/arm64/kernel/cpu_errata.c | 17 ----------------- arch/arm64/kernel/cpufeature.c | 13 +++++++++++++ 3 files changed, 15 insertions(+), 17 deletions(-) diff --git a/arch/arm64/include/asm/cpucaps.h b/arch/arm64/include/asm/cpucaps.h index 764ad4eef8591..07c9271b534df 100644 --- a/arch/arm64/include/asm/cpucaps.h +++ b/arch/arm64/include/asm/cpucaps.h @@ -40,6 +40,8 @@ cpucap_is_possible(const unsigned int cap) return IS_ENABLED(CONFIG_ARM64_BTI); case ARM64_HAS_TLB_RANGE: return IS_ENABLED(CONFIG_ARM64_TLB_RANGE); + case ARM64_WORKAROUND_2658417: + return IS_ENABLED(CONFIG_ARM64_ERRATUM_2658417); } return true; diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c index be66e94a21bda..86aed329d42c8 100644 --- a/arch/arm64/kernel/cpu_errata.c +++ b/arch/arm64/kernel/cpu_errata.c @@ -121,22 +121,6 @@ cpu_enable_cache_maint_trap(const struct arm64_cpu_capabilities *__unused) sysreg_clear_set(sctlr_el1, SCTLR_EL1_UCI, 0); } -static DEFINE_RAW_SPINLOCK(reg_user_mask_modification); -static void __maybe_unused -cpu_clear_bf16_from_user_emulation(const struct arm64_cpu_capabilities *__unused) -{ - struct arm64_ftr_reg *regp; - - regp = get_arm64_ftr_reg(SYS_ID_AA64ISAR1_EL1); - if (!regp) - return; - - raw_spin_lock(®_user_mask_modification); - if (regp->user_mask & ID_AA64ISAR1_EL1_BF16_MASK) - regp->user_mask &= ~ID_AA64ISAR1_EL1_BF16_MASK; - raw_spin_unlock(®_user_mask_modification); -} - #define CAP_MIDR_RANGE(model, v_min, r_min, v_max, r_max) \ .matches = is_affected_midr_range, \ .midr_range = MIDR_RANGE(model, v_min, r_min, v_max, r_max) @@ -727,7 +711,6 @@ const struct arm64_cpu_capabilities arm64_errata[] = { /* Cortex-A510 r0p0 - r1p1 */ ERRATA_MIDR_RANGE(MIDR_CORTEX_A510, 0, 0, 1, 1), MIDR_FIXED(MIDR_CPU_VAR_REV(1,1), BIT(25)), - .cpu_enable = cpu_clear_bf16_from_user_emulation, }, #endif #ifdef CONFIG_AMPERE_ERRATUM_AC03_CPU_38 diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index 234cf3189bee0..46508399796f9 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -2190,6 +2190,17 @@ static void cpu_enable_mte(struct arm64_cpu_capabilities const *cap) } #endif /* CONFIG_ARM64_MTE */ +static void user_feature_fixup(void) +{ + if (cpus_have_cap(ARM64_WORKAROUND_2658417)) { + struct arm64_ftr_reg *regp; + + regp = get_arm64_ftr_reg(SYS_ID_AA64ISAR1_EL1); + if (regp) + regp->user_mask &= ~ID_AA64ISAR1_EL1_BF16_MASK; + } +} + static void elf_hwcap_fixup(void) { #ifdef CONFIG_ARM64_ERRATUM_1742098 @@ -3357,6 +3368,8 @@ void __init setup_system_features(void) void __init setup_user_features(void) { + user_feature_fixup(); + setup_elf_hwcaps(arm64_elf_hwcaps); if (system_supports_32bit_el0()) {