From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 488F64A29; Sun, 4 May 2025 06:37:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746340651; cv=none; b=GrcT41TGCoSLhVGmPQU5QysnUGuLcNs8R72hzP7ufzv8coEjbiwSm1xOAkHQgRwLvSd/xAcN1zePCNVCwtWT/ZgsDWaz58jXU4Rs9R54ieRYvajtyyQLaPlNtKkRVMcwpTu5aafq1pInE+FZAk9DSxGp5cHrHQcWeKaCN1o7bY8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746340651; c=relaxed/simple; bh=LAaLGDDCnqM9OdvrMDXJ8ZuO0BHAmiSdlbjisjDSmmk=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Xk1zW7q/2lU6Ut+96xjTbs+2GQGg8I4arUoTgWDCfKR//MOUe8Pddzy25sAsL7ygoN4wauX99nFzaO5vn+BLCg+kAlJ3F0riC8389tDWSXHaTvmc5IPATPDd3+nM4TEm6PtZ8fpmrRs864kRYqvtfAm+D5aHjgMVvtAplnXVFoM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=KWeCQB9S; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="KWeCQB9S" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 67C65C4CEE7; Sun, 4 May 2025 06:37:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1746340650; bh=LAaLGDDCnqM9OdvrMDXJ8ZuO0BHAmiSdlbjisjDSmmk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=KWeCQB9St2AvAf+aJZboodBhKUKX50xHuR6rJgOFZAYRisIqaycdj437IN1tJyWYI FFofLCF/yOkm+hYWFv0WRlFdguJw6m5UcfzqmxBYFibhuw2zfwNOxv+cEejV5s4iyG 9yTXQWtbQANWcB8nraYa2D3PQV9ngL20P4pHB1q/FAWVHotioIoNe0TBP9gGYv87zo EhsQ2SoWyU3otrMuQCiMzm3hHQRJpDmjBteE+pXkrcykD4Z/Ync4fTY0Qhl9lXdswj PXkElzbpRsEfMZy8fFrxcrwApSZMJeQInMir2j2SxdrDm72nuOX3ycKKohWXLTYKop mmXK5PBQsO/YA== Date: Sun, 4 May 2025 08:37:27 +0200 From: Ingo Molnar To: linux-kernel@vger.kernel.org Cc: linux-tip-commits@vger.kernel.org, Yazen Ghannam , Mario Limonciello , "Borislav Petkov (AMD)" , x86@kernel.org Subject: Re: [tip: x86/platform] x86/CPU/AMD: Print the reason for the last reset Message-ID: References: <20250422234830.2840784-6-superm1@kernel.org> <174617858494.22196.5727323411231361285.tip-bot2@tip-bot2> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <174617858494.22196.5727323411231361285.tip-bot2@tip-bot2> * tip-bot2 for Yazen Ghannam wrote: > The register is accessed indirectly through a "PM" port in the FCH. Use > MMIO access in order to avoid restrictions with legacy port access. > > Use a late_initcall() to ensure that MMIO has been set up before trying to > access the register. > > This register was introduced with AMD Family 17h, so avoid access on older > families. There is no CPUID feature bit for this register. > > [ bp: Simplify the reason dumping loop. ] > > Signed-off-by: Yazen Ghannam > Co-developed-by: Mario Limonciello > Signed-off-by: Mario Limonciello > Signed-off-by: Borislav Petkov (AMD) > Link: https://lore.kernel.org/20250422234830.2840784-6-superm1@kernel.org > --- > Documentation/arch/x86/amd-debugging.rst | 42 ++++++++++++++++++- > arch/x86/include/asm/amd/fch.h | 1 +- > arch/x86/kernel/cpu/amd.c | 53 +++++++++++++++++++++++- > 3 files changed, 96 insertions(+) Looks mostly good, with a few minor comments: > +Random reboot issues > +==================== > +When a random reboot occurs, the high-level reason for the reboot is stored > +in a register that will persist onto the next boot. Please add an extra newline after the section title, as the rest of the document does. > +There are 6 classes of reasons for the reboot: > + * Software induced > + * Power state transition > + * Pin induced > + * Hardware induced > + * Remote reset > + * Internal CPU event > > +.. csv-table:: > + :header: "Bit", "Type", "Reason" > + :align: left > + > + "0", "Pin", "thermal pin BP_THERMTRIP_L was tripped" > + "1", "Pin", "power button was pressed for 4 seconds" > + "2", "Pin", "shutdown pin was shorted" > + "4", "Remote", "remote ASF power off command was received" > + "9", "Internal", "internal CPU thermal limit was tripped" > + "16", "Pin", "system reset pin BP_SYS_RST_L was tripped" > + "17", "Software", "software issued PCI reset" > + "18", "Software", "software wrote 0x4 to reset control register 0xCF9" > + "19", "Software", "software wrote 0x6 to reset control register 0xCF9" > + "20", "Software", "software wrote 0xE to reset control register 0xCF9" > + "21", "Sleep", "ACPI power state transition occurred" This line is a bit of an odd one out: all other classes are the first word of their classes, while this one only says 'Sleep', that is specific to the event. "ACPI-state" might be a better class I suspect. > + "22", "Pin", "keyboard reset pin KB_RST_L was asserted" > + "23", "Internal", "internal CPU shutdown event occurred" > + "24", "Hardware", "system failed to boot before failed boot timer expired" > + "25", "Hardware", "hardware watchdog timer expired" > + "26", "Remote", "remote ASF reset command was received" > + "27", "Internal", "an uncorrected error caused a data fabric sync flood event" > + "29", "Internal", "FCH and MP1 failed warm reset handshake" > + "30", "Internal", "a parity error occurred" > + "31", "Internal", "a software sync flood event occurred" > + > +This information is read by the kernel at bootup and is saved into the > +kernel ring buffer. When a random reboot occurs this message can be helpful > +to determine the next component to debug such an issue. The ring-buffer reference is a bit obtuse and confusing - printk is a log buffer. Maybe this refers to some earlier version of the patch? Also: s/determine the next component to debug such an issue. /determine the next component to debug. How about: This information is read by the kernel at bootup and printed into the syslog. When a random reboot occurs this message can be helpful to determine the next component to debug. > + [16] = "system reset pin BP_SYS_RST_L was tripped", s/tripped /shorted > + [22] = "keyboard reset pin KB_RST_L was asserted", s/asserted /shorted 'asserted' is fine too - but all 'pin' class messages should use consistent wording. > +static __init int print_s5_reset_status_mmio(void) > +{ > + unsigned long value; > + void __iomem *addr; > + int i; > + > + if (!cpu_feature_enabled(X86_FEATURE_ZEN)) > + return 0; > + > + addr = ioremap(FCH_PM_BASE + FCH_PM_S5_RESET_STATUS, sizeof(value)); > + if (!addr) > + return 0; > + > + value = ioread32(addr); > + iounmap(addr); > + > + for (i = 0; i <= ARRAY_SIZE(s5_reset_reason_txt); i++) { > + if (!(value & BIT(i))) > + continue; > + > + if (s5_reset_reason_txt[i]) > + pr_info("x86/amd: Previous system reset reason [0x%08lx]: %s\n", > + value, s5_reset_reason_txt[i]); Please use curly braces around multi-line statements. With those addressed: Reviewed-by: Ingo Molnar Thanks, Ingo