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 B6323FC02; Tue, 30 Apr 2024 10:12:20 +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=1714471940; cv=none; b=KTCh2xdqtxFORkcX6DlJW/AeuJxtkGCvr1WHKXJ8qS8xFekV5BGFmqf4KMEytDxINdyXAru/sOo9mroKaYSa9qCpQSNEusoOj4hvO3ebzjULlJK/gRWCBLV/rDQUUWjbj2C/3kQkt4HeUzFZ5iWNQ68s7TH1tHchOz9wqQ/m/rQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1714471940; c=relaxed/simple; bh=NURsOywy6CZA9cVVjd03JDCKuIynBZF1dYZyedRQp4A=; h=MIME-Version:References:In-Reply-To:From:Date:Message-ID:Subject: To:Cc:Content-Type; b=MabhvcXM5m4MI1SP9Sak27I6m3FrCSphwbxbcBI8tpJ77Gldtv5f2ME9qCjgng5XXmQbWtkBr0fA+u45ZjVhNPzN8SqsRH/a+k+NHANdgwJweSwRL900Qmy4QxStgnKsK/6LZRcYZfJos6WXNucBR0/Hb+Bk/p9QpS+3+HfnpUc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=X+vqZZvO; 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="X+vqZZvO" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5BE31C4AF1C; Tue, 30 Apr 2024 10:12:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1714471940; bh=NURsOywy6CZA9cVVjd03JDCKuIynBZF1dYZyedRQp4A=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=X+vqZZvOjZypgq0mBbFOU/tDwtRlo20JPY8W7/+T5hEB0EU1kBFvrjrXDoD4LVL9U nXvbZl2/jb3FB5uawtClONaKcEkIhs8Il0/LrR5sGfphOqy0iROZ8iXzElUPONM0YI JhZnUe1n8K8hiV+HA719XaWokj3xQp8wSlDLpm9IIyOZQ2FfvMiae63ZxnGe5b/U9V 1BQAUSZhoQo8YR8IYNRsg8um71Aa8K92G9QCazzVpJ5LtEq1HmU3DyU4jpJ1eKvunb HEhkZ5HWCjr9sz+mBoNCAN+HGbn/jSsz8PeeVKXKAWLlTowQ0bWldxkeoa56jXG7k1 NPRWpilKAM0rg== Received: by mail-ot1-f46.google.com with SMTP id 46e09a7af769-6ea0a6856d7so800314a34.1; Tue, 30 Apr 2024 03:12:20 -0700 (PDT) X-Forwarded-Encrypted: i=1; AJvYcCVPjBFl/A1sfWanWDJlE5O2vUshyqRc2/k4kqeB7NRdz32NPBe2ZOlZnSBvypAx9zZYp1biN4UNvkPFlY2ZnMhOm4WgC+42A5U5F22yl27dXvvVABv5CFno1rOD+UIupce/ X-Gm-Message-State: AOJu0Yx79LwTIhgS5aqIE4cjNRETckJAvlVXy5yjWFKmreJvoM+RRaAX YGjW8qPkJ6tLYHO94Kh0nlXvRvOTOHchN/XjvS76kj8Q52RmJs5ev1UeY9iTUhRdPPOJl6hZJL4 z2e/oFU0QAwvbMVL8LGACfTxDjkk= X-Google-Smtp-Source: AGHT+IEkOTp4jMU7eudwtXqkvXjt6cTTGERhb/sNQV/MqoRF8MN5nzaetIoEPLvwr3sNLlYci5wgFWtcOQTdv18nlQ0= X-Received: by 2002:a4a:9287:0:b0:5af:be60:ccdc with SMTP id i7-20020a4a9287000000b005afbe60ccdcmr3516316ooh.0.1714471939510; Tue, 30 Apr 2024 03:12:19 -0700 (PDT) Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 References: <20240426135126.12802-1-Jonathan.Cameron@huawei.com> <20240426135126.12802-5-Jonathan.Cameron@huawei.com> <80a2e07f-ecb2-48af-b2be-646f17e0e63e@redhat.com> <20240430102838.00006e04@Huawei.com> In-Reply-To: <20240430102838.00006e04@Huawei.com> From: "Rafael J. Wysocki" Date: Tue, 30 Apr 2024 12:12:07 +0200 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v8 04/16] ACPI: processor: Move checks and availability of acpi_processor earlier To: Jonathan Cameron Cc: Gavin Shan , Thomas Gleixner , Peter Zijlstra , linux-pm@vger.kernel.org, loongarch@lists.linux.dev, linux-acpi@vger.kernel.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, x86@kernel.org, Russell King , "Rafael J . Wysocki" , Miguel Luis , James Morse , Salil Mehta , Jean-Philippe Brucker , Catalin Marinas , Will Deacon , Marc Zyngier , Hanjun Guo , Ingo Molnar , Borislav Petkov , Dave Hansen , linuxarm@huawei.com, justin.he@arm.com, jianyong.wu@arm.com, Lorenzo Pieralisi , Sudeep Holla Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Tue, Apr 30, 2024 at 11:28=E2=80=AFAM Jonathan Cameron wrote: > > On Tue, 30 Apr 2024 14:17:24 +1000 > Gavin Shan wrote: > > > On 4/26/24 23:51, Jonathan Cameron wrote: > > > Make the per_cpu(processors, cpu) entries available earlier so that > > > they are available in arch_register_cpu() as ARM64 will need access > > > to the acpi_handle to distinguish between acpi_processor_add() > > > and earlier registration attempts (which will fail as _STA cannot > > > be checked). > > > > > > Reorder the remove flow to clear this per_cpu() after > > > arch_unregister_cpu() has completed, allowing it to be used in > > > there as well. > > > > > > Note that on x86 for the CPU hotplug case, the pr->id prior to > > > acpi_map_cpu() may be invalid. Thus the per_cpu() structures > > > must be initialized after that call or after checking the ID > > > is valid (not hotplug path). > > > > > > Signed-off-by: Jonathan Cameron > > > > > > --- > > > v8: On buggy bios detection when setting per_cpu structures > > > do not carry on. > > > Fix up the clearing of per cpu structures to remove unwanted > > > side effects and ensure an error code isn't use to reference the= m. > > > --- > > > drivers/acpi/acpi_processor.c | 79 +++++++++++++++++++++-----------= --- > > > 1 file changed, 48 insertions(+), 31 deletions(-) > > > > > > diff --git a/drivers/acpi/acpi_processor.c b/drivers/acpi/acpi_proces= sor.c > > > index ba0a6f0ac841..3b180e21f325 100644 > > > --- a/drivers/acpi/acpi_processor.c > > > +++ b/drivers/acpi/acpi_processor.c > > > @@ -183,8 +183,38 @@ static void __init acpi_pcc_cpufreq_init(void) {= } > > > #endif /* CONFIG_X86 */ > > > > > > /* Initialization */ > > > +static DEFINE_PER_CPU(void *, processor_device_array); > > > + > > > +static bool acpi_processor_set_per_cpu(struct acpi_processor *pr, > > > + struct acpi_device *device) > > > +{ > > > + BUG_ON(pr->id >=3D nr_cpu_ids); > > > > One blank line after BUG_ON() if we need to follow original implementat= ion. > > Sure unintentional - I'll put that back. > > > > > > + /* > > > + * Buggy BIOS check. > > > + * ACPI id of processors can be reported wrongly by the BIOS. > > > + * Don't trust it blindly > > > + */ > > > + if (per_cpu(processor_device_array, pr->id) !=3D NULL && > > > + per_cpu(processor_device_array, pr->id) !=3D device) { > > > + dev_warn(&device->dev, > > > + "BIOS reported wrong ACPI id %d for the processo= r\n", > > > + pr->id); > > > + /* Give up, but do not abort the namespace scan. */ > > > > It depends on how the return value is handled by the caller if the name= space > > is continued to be scanned. The caller can be acpi_processor_hotadd_ini= t() > > and acpi_processor_get_info() after this patch is applied. So I think t= his > > specific comment need to be moved to the caller. > > Good point. This gets messy and was an unintended change. > > Previously the options were: > 1) acpi_processor_get_info() failed for other reasons - this code was nev= er called. > 2) acpi_processor_get_info() succeeded without acpi_processor_hotadd_init= (non hotplug) > this code then ran and would paper over the problem doing a bunch of c= leanup under err. > 3) acpi_processor_get_info() succeeded with acpi_processor_hotadd_init ca= lled. > This code then ran and would paper over the problem doing a bunch of c= leanup under err. > > We should maintain that or argue cleanly against it. The return value needs to be propagated to acpi_processor_add() so it can decide what to do with it. Now, acpi_processor_add() can only return 1 if the CPU has been successfully registered and initialized, so it is regarded as available (but it may not be online to start with). Returning 0 from it may get messy, because acpi_default_enumeration() will get called and it will attempt to create a platform device for the CPU, so in all cases in which the CPU is not regarded as available when acpi_processor_add() returns, it should return an error code (the exact value doesn't matter for its caller so long as it is negative). > This isn't helped the the fact I have no idea which cases we care about f= or that bios > bug handling. Do any of those bios's ever do hotplug? Guess we have to = try and maintain > whatever protection this was offering. > > Also, the original code leaks data in some paths and I have limited idea > of whether it is intentional or not. So to tidy the issue up that you've = identified > I'll need to try and make that code consistent first. I agree. > I suspect the only way to do that is going to be to duplicate the allocat= ions we > 'want' to leak to deal with the bios bug detection. > > For example acpi_processor_get_info() failing leaks pr and pr->throttling= .shared_cpu_map > before this series. After this series we need pr to leak because it's use= d for the detection > via processor_device_array. > > I'll work through this but it's going to be tricky to tell if we get righ= t. > Step 1 will be closing the existing leaks and then we will have something > consistent to build on. Sounds good to me.