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 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 17D4FC531D0 for ; Mon, 27 Jul 2026 16:35:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: MIME-Version:Message-Id:Date:Subject:Cc:To:From:Reply-To:Content-Type: Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender: Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References:List-Owner; bh=Bojp+Gj2MsGgWa6SFvQHDXEB74ddJnQUrupbLmP9uO8=; b=voCu/HAX2MvVFjv3J7DWWbmlBb UmPhMUbTTD0cAeklVA/zDQl9W4MEk+AXPGaveqhwbnQNZiiONR/Vk902oSFwfwGlAZJScmtbsTZtE IAf6ZlRxeTk1XzWOsckoDxdx/iTNET2lFvAMmv1nVfGooZsW3xlP7jZ6z5Y2WBqq1IAZh0JEA6MbP Iz3HwZHFXdYtuIpnFhtpZHVhdsx1Cc0MrNhtLWlHITKSSNaGc2wHUfsRvB0FJiLAB2mVmr6HUUhJc QRX8SNSrxDcgf3g0vIYmikOHm1METAuKUKkXDOkY9yqgUhmFORvMnH/CLpUmv0qxuUjyy1RaXSzw8 LlRqFJUg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1woOIW-00000003MQe-1PGk; Mon, 27 Jul 2026 16:35:24 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1woOIU-00000003MPb-0zIi for linux-arm-kernel@lists.infradead.org; Mon, 27 Jul 2026 16:35:24 +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 A563B1682; Mon, 27 Jul 2026 09:35:16 -0700 (PDT) Received: from login2.euhpc2.arm.com (login2.euhpc2.arm.com [10.58.100.22]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id CBAD23F86F; Mon, 27 Jul 2026 09:35:19 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1785170120; bh=yxFHeOoZdS8zEqrcdNVtMTm66GMVbYUle1phnUPxvHQ=; h=From:To:Cc:Subject:Date:From; b=F04GVQGzplqCXBortlpxBkqgrG/yWm9goH5HY4zaLQHHZPpC64/7asyKVPUcsvyBw awDww5t6RdQN2iNig4R3cwjmONjWrDhPe5VAdj1/U+Y5zWTVQ/6kBstbso04gjk8/U fqiyJftHIu9ART3ZTm6QllzMcMKly+fRWifIbXVQ= From: Vladimir Murzin To: linux-arm-kernel@lists.infradead.org Cc: mark.rutland@arm.com, maz@kernel.org, will@kernel.org, catalin.marinas@arm.com, ruanjinjie@huawei.com, liaochang1@huawei.com Subject: [RFC PATCH v2 00/45] arm64: Add support for FEAT_NMI Date: Mon, 27 Jul 2026 17:34:08 +0100 Message-Id: <20260727163453.7969-1-vladimir.murzin@arm.com> X-Mailer: git-send-email 2.24.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260727_093522_380942_DA623818 X-CRM114-Status: GOOD ( 21.64 ) 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 FEAT_NMI provides an architected mechanism for supporting non-maskable interrupts (NMIs) and less-masked interrupts (LMIs). Since we already support pseudo-NMIs via priority masking, introducing another flavour of NMI on top of the existing infrastructure could easily become messy, making the code harder to follow and reason about. To avoid that, this series first makes room for the new NMI "tenant" by restructuring the existing exception masking logic. The main idea is to separate the logical view of exception state from its hardware representation. To achieve this, we introduce logical exception contexts that can be mapped onto the corresponding hardware state. This naturally consolidates the hardware-specific handling into a small number of places, while allowing the rest of the code to operate purely in terms of logical exception contexts. Since this restructuring is non-trivial and carries a risk of subtle behavioural changes, the series adds extensive debug checks to verify that the hardware state always matches the expected logical state. With this restructuring in place, wiring FEAT_NMI into the new framework becomes much more manageable. This work would not have been possible without the contributions of Ada Couprie Diaz, Mark Brown, and Lorenzo Pieralisi - please credit them for everything that works well. Any remaining bugs or issues are entirely my own. I'd especially appreciate feedback on the overall approach. Please don't hesitate to bikeshed the naming or other details - improving clarity is one of the main goals of this series. Of course, technical review is more than welcome as well. The series would also benefit from extensive testing on real hardware (without NMI, with pseudo-NMI, and with FEAT_NMI), as most of the testing so far has been done on QEMU and Fast Model. Changelog RFC v1 -> RFC v2 - Rebased on v7.2-rc5. - Improved commit descriptions. - Split some patches into smaller ones. - Added a graceful fallback for IPI requests when FEAT_NMI is supported by the CPU but unsupported by the interrupt controller. - Split the GICv3 preparation from the FEAT_GICv3_NMI implementation. - Added NMI support to GICv5, primarily as an illustration of the implementation, although it also happens to work on Fast Model. - Added review tags only to unchanged patches. Review tags were intentionally dropped from modified patches to reflect those changes and encourage re-review. RFC v1: https://lore.kernel.org/linux-arm-kernel/20260709121333.23507-1-vladimir.murzin@arm.com/T/#m6a9321ce39d4a8b1c2111638e5dde827336f355d Thanks! Vladimir Ada Couprie Diaz (20): arm64: debug: don't mask DAIF for mdscr_write() arm64: hibernate: mask DAIF before restoring hibernated kernel arm64: suspend: rely on daif helpers to handle PMR arm64: entry: mask DAIF before returning from C EL1 handlers irqchip/gic-v3: make the unmasking of pseudo-NMIs explicit when handling IRQs arm64: irqflags: Introduce arm64-specific irqflags type arm64: irqflags: save and use both DAIF and PMR arm64: interrupts: Add common exception state helpers arm64: entry: Introduce entry specific exception masking helpers arm64: entry: replace DAIF helpers with entry helpers arm64: interrupts: Introduce exception masking save/restore helpers arm64: interrupts: introduce a helper for GIC priority initialization arm64: replace local_daif helpers arm64: cpuidle: use new helpers to bypass interrupt priority masking arm64: remove daifflags.h arm64: gicv3: remove GIC_PRIO_PSR_I_SET arm64: ptrace: Add PSR_ALLINT_BIT arm64: cpufeature: Detect PE support for FEAT_NMI arm64: nmi: Manage masking for superpriority interrupts arm64: irq: Report FEAT_NMI masking local IRQs Lorenzo Pieralisi (2): irqchip/gic-v3: Prepare for FEAT_GICv3_NMI support irqchip/gic-v3: Implement FEAT_GICv3_NMI support Mark Brown (5): arm64: booting: Document boot requirements for FEAT_NMI arm64: sysreg: Add definitions for immediate versions of MSR ALLINT arm64: idreg: Add an override for FEAT_NMI arm64: nmi: Add handling of superpriority interrupts as NMIs arm64: nmi: Add Kconfig for NMI Vladimir Murzin (18): arm64: ptrace: Remove INIT_PSTATE_EL2 arm64: hibernate: Restore DAIF state on error arm64: suspend: Initialize PMR on resume arm64: entry: Avoid unnecessary local_irq_disable() on kernel exit arm64: process: Use helper to check exception state arm64: cpufeature: Remove system_has_prio_mask_debugging() arm64: irqflags: Switch to CONFIG_DEBUG_IRQFLAGS arm64: Kconfig: Remove CONFIG_ARM64_DEBUG_PRIORITY_MASKING efi/runtime-wrappers: Permit architectures to override IRQ flags checks arm64/efi: Implement override for IRQ flags checks arm64: suspend: Always initialise PSTATE.ALLINT arm64/efi: Add ALLINT to IRQ flags checks arm64: kprobes: Disable NMIs arm64: smp: Abstract SGI and LPI operations arm64: smp: Fall back to IRQ when IPI NMI request fails arm64: smp: Add NMI support for LPI-backed IPIs irqchip/gic-v5: Add NMI support for PPIs, SPIs and LPIs irqchip/gic-v5: Add NMI support for IPIs Documentation/arch/arm64/booting.rst | 6 + arch/arm/include/asm/arch_gicv3.h | 6 +- arch/arm64/Kconfig | 29 +- arch/arm64/include/asm/arch_gicv3.h | 7 +- arch/arm64/include/asm/assembler.h | 24 +- arch/arm64/include/asm/cpucaps.h | 2 + arch/arm64/include/asm/cpufeature.h | 14 +- arch/arm64/include/asm/cpuidle.h | 18 +- arch/arm64/include/asm/daifflags.h | 144 -------- arch/arm64/include/asm/efi.h | 42 ++- arch/arm64/include/asm/entry-common.h | 10 +- .../include/asm/interrupts/common_flags.h | 259 +++++++++++++ arch/arm64/include/asm/interrupts/entry.h | 119 ++++++ arch/arm64/include/asm/interrupts/masking.h | 170 +++++++++ arch/arm64/include/asm/irqflags.h | 149 ++++---- arch/arm64/include/asm/kvm_host.h | 1 - arch/arm64/include/asm/mmu_context.h | 1 - arch/arm64/include/asm/ptrace.h | 27 +- arch/arm64/include/asm/sysreg.h | 2 + arch/arm64/include/uapi/asm/ptrace.h | 1 + arch/arm64/kernel/acpi.c | 15 +- arch/arm64/kernel/cpufeature.c | 68 +++- arch/arm64/kernel/debug-monitors.c | 4 - arch/arm64/kernel/entry-common.c | 347 +++++++++++++----- arch/arm64/kernel/entry.S | 18 +- arch/arm64/kernel/hibernate.c | 26 +- arch/arm64/kernel/irq.c | 45 ++- arch/arm64/kernel/machine_kexec.c | 4 +- arch/arm64/kernel/pi/idreg-override.c | 1 + arch/arm64/kernel/probes/kprobes.c | 24 +- arch/arm64/kernel/process.c | 24 +- arch/arm64/kernel/setup.c | 4 +- arch/arm64/kernel/signal.c | 1 - arch/arm64/kernel/smp.c | 230 ++++++++---- arch/arm64/kernel/suspend.c | 26 +- arch/arm64/kernel/traps.c | 1 - arch/arm64/kvm/hyp/nvhe/switch.c | 2 +- arch/arm64/kvm/hyp/vgic-v3-sr.c | 7 +- arch/arm64/kvm/hyp/vhe/switch.c | 14 +- arch/arm64/mm/fault.c | 1 - arch/arm64/mm/mmu.c | 7 +- arch/arm64/mm/proc.S | 7 + arch/arm64/tools/cpucaps | 2 + drivers/firmware/efi/runtime-wrappers.c | 32 +- drivers/irqchip/irq-gic-v3.c | 137 ++++++- drivers/irqchip/irq-gic-v5.c | 244 +++++++++++- include/linux/irqchip/arm-gic-v3-prio.h | 8 - include/linux/irqchip/arm-gic-v3.h | 4 + kernel/irq/handle.c | 3 +- kernel/irq/manage.c | 11 +- 50 files changed, 1734 insertions(+), 614 deletions(-) delete mode 100644 arch/arm64/include/asm/daifflags.h create mode 100644 arch/arm64/include/asm/interrupts/common_flags.h create mode 100644 arch/arm64/include/asm/interrupts/entry.h create mode 100644 arch/arm64/include/asm/interrupts/masking.h -- 2.34.1