From patchwork Wed Jun 4 00:15:14 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ricardo Neri X-Patchwork-Id: 895262 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.13]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7FB9D6AA7; Wed, 4 Jun 2025 00:18:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.13 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1748996285; cv=none; b=Dq9QdoumhRc+g0+MbnX3BjyR7UcYzQsFnwFYIA1StDyJfrsf8J0/v69b9Ire5uP5Tx1rMoZshbLiZWhrMklzgi0l4Ay7SaL8DgQJFgzdoiwUxKsjzMyB6AfJLCFOA0rlKKxgLsKzeowu/CnK84ySCRd8OdzJ3MdG3KDJMjTsBtM= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1748996285; c=relaxed/simple; bh=pPl7b6XtSmseHCkcheCWPHAL+avH9O3JDG2Rt0uU5Cw=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=qKn4HhF68oGP7L67Uf2XukwVJEdB/LIGmEhBxLDp73sXyXTmQqmwVoT68U3g+Ks3234p83Ueulm1qCcAtkVK4BAdIoFMHKxaafS1PNOzEwzNGriHAHkEhmFJB65HtK1mMFr5HlHhGcaMVdwte+pp92SrRKGtT9iIcDUGQQ2Rxik= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com; spf=none smtp.mailfrom=linux.intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=Z/jyPP6Z; arc=none smtp.client-ip=198.175.65.13 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="Z/jyPP6Z" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1748996284; x=1780532284; h=from:date:subject:mime-version:content-transfer-encoding: message-id:references:in-reply-to:to:cc; bh=pPl7b6XtSmseHCkcheCWPHAL+avH9O3JDG2Rt0uU5Cw=; b=Z/jyPP6ZYBpX+Z8b/Ruo3OYK6qvjtsNsreN1tufhB9h1i66HotpgxIGb u+AhljMyLzBNh55nsSU9jiCxNTyjkOhtF/fFWlWKK7GEjbJCdwcD/gVaF xSLgMb73uhjwcqZrDVtKpKLUKdrfl8ktdnHzK7vttxc9LcC2wuvr7KW2K wTdNZ5ucEHgevR8KGoLM2DMiDvIYTz5pZX4uNtpmlZ+C4DhNYW6l2edEk Kqb0ImjHE/rpVNC98StelQG7e2LYV1YGbw6kN9kDMLyVtpLDkSRWAw0ws iQbDk6H8pjFVLNi6p0hfdNSSl8XS81wYj22iUQ3JIZrZlDX0O2sIWKWHt Q==; X-CSE-ConnectionGUID: UCdK2FJ6QLOGmSZhffrvwQ== X-CSE-MsgGUID: nMnDq8f5QlCX9vozTg+xLw== X-IronPort-AV: E=McAfee;i="6700,10204,11453"; a="62112933" X-IronPort-AV: E=Sophos;i="6.16,207,1744095600"; d="scan'208";a="62112933" Received: from fmviesa005.fm.intel.com ([10.60.135.145]) by orvoesa105.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 03 Jun 2025 17:18:01 -0700 X-CSE-ConnectionGUID: CM18UCLdQiaVfJzzHWlACw== X-CSE-MsgGUID: 1Qu4mFWMT3SAvRMiB7sUoQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.16,207,1744095600"; d="scan'208";a="149904454" Received: from unknown (HELO [172.25.112.21]) ([172.25.112.21]) by fmviesa005.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 03 Jun 2025 17:18:00 -0700 From: Ricardo Neri Date: Tue, 03 Jun 2025 17:15:14 -0700 Subject: [PATCH v4 02/10] x86/acpi: Move acpi_wakeup_cpu() and helpers to smpwakeup.c Precedence: bulk X-Mailing-List: linux-acpi@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-Id: <20250603-rneri-wakeup-mailbox-v4-2-d533272b7232@linux.intel.com> References: <20250603-rneri-wakeup-mailbox-v4-0-d533272b7232@linux.intel.com> In-Reply-To: <20250603-rneri-wakeup-mailbox-v4-0-d533272b7232@linux.intel.com> To: x86@kernel.org, Krzysztof Kozlowski , Conor Dooley , Rob Herring , "K. Y. Srinivasan" , Haiyang Zhang , Wei Liu , Dexuan Cui , Michael Kelley , "Rafael J. Wysocki" Cc: Saurabh Sengar , Chris Oo , "Kirill A. Shutemov" , linux-hyperv@vger.kernel.org, devicetree@vger.kernel.org, linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org, "Ravi V. Shankar" , Ricardo Neri , Yunhong Jiang , Ricardo Neri X-Mailer: b4 0.13.0 X-Developer-Signature: v=1; a=ed25519-sha256; t=1748996287; l=9450; i=ricardo.neri-calderon@linux.intel.com; s=20250602; h=from:subject:message-id; bh=pPl7b6XtSmseHCkcheCWPHAL+avH9O3JDG2Rt0uU5Cw=; b=1CCcC47E8CEf8V9oEUfYfQ2PLhaqmKAjC4IoI7CWqbrsBCxPy6I600CaJjUQDi5DwST4QzLSO TFA/jgJvaoLBYkCri6ifvEz4vr70dPsF1WtSmu1lHdmWpzLhFz5Sym3 X-Developer-Key: i=ricardo.neri-calderon@linux.intel.com; a=ed25519; pk=NfZw5SyQ2lxVfmNMaMR6KUj3+0OhcwDPyRzFDH9gY2w= The bootstrap processor uses acpi_wakeup_cpu() to indicate to firmware that it wants to boot a secondary CPU using a mailbox as described in the Multiprocessor Wakeup Structure of the ACPI specification. The platform firmware may implement the mailbox as described in the ACPI specification but enumerate it using a DeviceTree graph. An example of this is OpenHCL paravisor. Move the code used to setup and use the mailbox for CPU wakeup out of the ACPI directory into a new smpwakeup.c file that both ACPI and DeviceTree can use. No functional changes are intended. Co-developed-by: Yunhong Jiang Signed-off-by: Yunhong Jiang Signed-off-by: Ricardo Neri --- Changes since v3: - Create a new file smpwakeup.c instead of relocating it to smpboot.c. (Rafael) Changes since v2: - Only move to smpboot.c the portions of the code that configure and use the mailbox. This also resolved the compile warnings about unused functions that Michael Kelley reported. - Edited the commit message for clarity. Changes since v1: - None. --- arch/x86/Kconfig | 7 ++++ arch/x86/kernel/Makefile | 1 + arch/x86/kernel/acpi/madt_wakeup.c | 76 ---------------------------------- arch/x86/kernel/smpwakeup.c | 83 ++++++++++++++++++++++++++++++++++++++ 4 files changed, 91 insertions(+), 76 deletions(-) diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index cb0f4af31789..82147edb355a 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -1113,6 +1113,13 @@ config X86_LOCAL_APIC depends on X86_64 || SMP || X86_UP_APIC || PCI_MSI select IRQ_DOMAIN_HIERARCHY +config X86_MAILBOX_WAKEUP + def_bool y + depends on OF || ACPI_MADT_WAKEUP + depends on X86_64 + depends on SMP + depends on X86_LOCAL_APIC + config ACPI_MADT_WAKEUP def_bool y depends on X86_64 diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile index 99a783fd4691..8f078af42a71 100644 --- a/arch/x86/kernel/Makefile +++ b/arch/x86/kernel/Makefile @@ -94,6 +94,7 @@ apm-y := apm_32.o obj-$(CONFIG_APM) += apm.o obj-$(CONFIG_SMP) += smp.o obj-$(CONFIG_SMP) += smpboot.o +obj-$(CONFIG_X86_MAILBOX_WAKEUP) += smpwakeup.o obj-$(CONFIG_X86_TSC) += tsc_sync.o obj-$(CONFIG_SMP) += setup_percpu.o obj-$(CONFIG_X86_MPPARSE) += mpparse.o diff --git a/arch/x86/kernel/acpi/madt_wakeup.c b/arch/x86/kernel/acpi/madt_wakeup.c index 4033c804307a..a7e0158269b0 100644 --- a/arch/x86/kernel/acpi/madt_wakeup.c +++ b/arch/x86/kernel/acpi/madt_wakeup.c @@ -2,12 +2,10 @@ #include #include #include -#include #include #include #include #include -#include #include #include #include @@ -15,12 +13,6 @@ #include #include -/* Physical address of the Multiprocessor Wakeup Structure mailbox */ -static u64 acpi_mp_wake_mailbox_paddr __ro_after_init; - -/* Virtual address of the Multiprocessor Wakeup Structure mailbox */ -static struct acpi_madt_multiproc_wakeup_mailbox *acpi_mp_wake_mailbox; - static u64 acpi_mp_pgd __ro_after_init; static u64 acpi_mp_reset_vector_paddr __ro_after_init; @@ -127,63 +119,6 @@ static int __init acpi_mp_setup_reset(u64 reset_vector) return 0; } -static int acpi_wakeup_cpu(u32 apicid, unsigned long start_ip) -{ - if (!acpi_mp_wake_mailbox_paddr) { - pr_warn_once("No MADT mailbox: cannot bringup secondary CPUs. Booting with kexec?\n"); - return -EOPNOTSUPP; - } - - /* - * Remap mailbox memory only for the first call to acpi_wakeup_cpu(). - * - * Wakeup of secondary CPUs is fully serialized in the core code. - * No need to protect acpi_mp_wake_mailbox from concurrent accesses. - */ - if (!acpi_mp_wake_mailbox) { - acpi_mp_wake_mailbox = memremap(acpi_mp_wake_mailbox_paddr, - sizeof(*acpi_mp_wake_mailbox), - MEMREMAP_WB); - } - - /* - * Mailbox memory is shared between the firmware and OS. Firmware will - * listen on mailbox command address, and once it receives the wakeup - * command, the CPU associated with the given apicid will be booted. - * - * The value of 'apic_id' and 'wakeup_vector' must be visible to the - * firmware before the wakeup command is visible. smp_store_release() - * ensures ordering and visibility. - */ - acpi_mp_wake_mailbox->apic_id = apicid; - acpi_mp_wake_mailbox->wakeup_vector = start_ip; - smp_store_release(&acpi_mp_wake_mailbox->command, - ACPI_MP_WAKE_COMMAND_WAKEUP); - - /* - * Wait for the CPU to wake up. - * - * The CPU being woken up is essentially in a spin loop waiting to be - * woken up. It should not take long for it wake up and acknowledge by - * zeroing out ->command. - * - * ACPI specification doesn't provide any guidance on how long kernel - * has to wait for a wake up acknowledgment. It also doesn't provide - * a way to cancel a wake up request if it takes too long. - * - * In TDX environment, the VMM has control over how long it takes to - * wake up secondary. It can postpone scheduling secondary vCPU - * indefinitely. Giving up on wake up request and reporting error opens - * possible attack vector for VMM: it can wake up a secondary CPU when - * kernel doesn't expect it. Wait until positive result of the wake up - * request. - */ - while (READ_ONCE(acpi_mp_wake_mailbox->command)) - cpu_relax(); - - return 0; -} - static void acpi_mp_disable_offlining(struct acpi_madt_multiproc_wakeup *mp_wake) { cpu_hotplug_disable_offlining(); @@ -246,14 +181,3 @@ int __init acpi_parse_mp_wake(union acpi_subtable_headers *header, return 0; } - -void __init acpi_setup_mp_wakeup_mailbox(u64 mailbox_paddr) -{ - acpi_mp_wake_mailbox_paddr = mailbox_paddr; - apic_update_callback(wakeup_secondary_cpu_64, acpi_wakeup_cpu); -} - -struct acpi_madt_multiproc_wakeup_mailbox *acpi_get_mp_wakeup_mailbox(void) -{ - return acpi_mp_wake_mailbox; -} diff --git a/arch/x86/kernel/smpwakeup.c b/arch/x86/kernel/smpwakeup.c new file mode 100644 index 000000000000..e34ffbfffaf5 --- /dev/null +++ b/arch/x86/kernel/smpwakeup.c @@ -0,0 +1,83 @@ +// SPDX-License-Identifier: GPL-2.0-or-later + +#include +#include +#include +#include +#include +#include +#include + +/* Physical address of the Multiprocessor Wakeup Structure mailbox */ +static u64 acpi_mp_wake_mailbox_paddr __ro_after_init; + +/* Virtual address of the Multiprocessor Wakeup Structure mailbox */ +static struct acpi_madt_multiproc_wakeup_mailbox *acpi_mp_wake_mailbox; + +static int acpi_wakeup_cpu(u32 apicid, unsigned long start_ip) +{ + if (!acpi_mp_wake_mailbox_paddr) { + pr_warn_once("No MADT mailbox: cannot bringup secondary CPUs. Booting with kexec?\n"); + return -EOPNOTSUPP; + } + + /* + * Remap mailbox memory only for the first call to acpi_wakeup_cpu(). + * + * Wakeup of secondary CPUs is fully serialized in the core code. + * No need to protect acpi_mp_wake_mailbox from concurrent accesses. + */ + if (!acpi_mp_wake_mailbox) { + acpi_mp_wake_mailbox = memremap(acpi_mp_wake_mailbox_paddr, + sizeof(*acpi_mp_wake_mailbox), + MEMREMAP_WB); + } + + /* + * Mailbox memory is shared between the firmware and OS. Firmware will + * listen on mailbox command address, and once it receives the wakeup + * command, the CPU associated with the given apicid will be booted. + * + * The value of 'apic_id' and 'wakeup_vector' must be visible to the + * firmware before the wakeup command is visible. smp_store_release() + * ensures ordering and visibility. + */ + acpi_mp_wake_mailbox->apic_id = apicid; + acpi_mp_wake_mailbox->wakeup_vector = start_ip; + smp_store_release(&acpi_mp_wake_mailbox->command, + ACPI_MP_WAKE_COMMAND_WAKEUP); + + /* + * Wait for the CPU to wake up. + * + * The CPU being woken up is essentially in a spin loop waiting to be + * woken up. It should not take long for it wake up and acknowledge by + * zeroing out ->command. + * + * ACPI specification doesn't provide any guidance on how long kernel + * has to wait for a wake up acknowledgment. It also doesn't provide + * a way to cancel a wake up request if it takes too long. + * + * In TDX environment, the VMM has control over how long it takes to + * wake up secondary. It can postpone scheduling secondary vCPU + * indefinitely. Giving up on wake up request and reporting error opens + * possible attack vector for VMM: it can wake up a secondary CPU when + * kernel doesn't expect it. Wait until positive result of the wake up + * request. + */ + while (READ_ONCE(acpi_mp_wake_mailbox->command)) + cpu_relax(); + + return 0; +} + +void __init acpi_setup_mp_wakeup_mailbox(u64 mailbox_paddr) +{ + acpi_mp_wake_mailbox_paddr = mailbox_paddr; + apic_update_callback(wakeup_secondary_cpu_64, acpi_wakeup_cpu); +} + +struct acpi_madt_multiproc_wakeup_mailbox *acpi_get_mp_wakeup_mailbox(void) +{ + return acpi_mp_wake_mailbox; +}