From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from frasgout.his.huawei.com (frasgout.his.huawei.com [185.176.79.56]) (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 9E5021BC31; Wed, 17 Apr 2024 18:57:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.176.79.56 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1713380260; cv=none; b=exnDQTQKk/OCSYvhI4mc21rr08RSyF2jf/L0IWhzsFSSyx9FrF+x3VuX3ppDe877mLuqHaw4hP4HDfdOUIiEQ+ugC/kCsBJIAfofzpQioOZv69aACVagPVGOUbT3KkKWp0k8cDO4hQIWZVtslNWCOwxUui6lnirXnZ9tXfzX+E4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1713380260; c=relaxed/simple; bh=KVXA+NdTpK4SJ+PCuiRSu/BpgwGrYOPU4BiLvB8PwtM=; h=Date:From:To:CC:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=M6opKxF0ZYJ62PhKsAsjrJpp7TOG/1IKkzjHp4vEpB0AaI3f5I+1b6z6sRWQwuNDuJnSGPJAZReCpuKRaWQqLO6vTADlkJQx7hlgS8nRjzI/YT7gyVOb1nWSYO+dPv1m0+nq8hsghuG3MvcaGt6A9kFNri6i7Z2y00ZlRZMmglw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=Huawei.com; spf=pass smtp.mailfrom=huawei.com; arc=none smtp.client-ip=185.176.79.56 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=Huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Received: from mail.maildlp.com (unknown [172.18.186.231]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4VKVTw3ff0z6J9Th; Thu, 18 Apr 2024 02:55:32 +0800 (CST) Received: from lhrpeml500005.china.huawei.com (unknown [7.191.163.240]) by mail.maildlp.com (Postfix) with ESMTPS id 12A0E140519; Thu, 18 Apr 2024 02:57:33 +0800 (CST) Received: from localhost (10.48.146.224) by lhrpeml500005.china.huawei.com (7.191.163.240) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.1.2507.35; Wed, 17 Apr 2024 19:57:32 +0100 Date: Wed, 17 Apr 2024 19:57:30 +0100 From: Jonathan Cameron To: "Rafael J. Wysocki" CC: Salil Mehta , 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 , Miguel Luis , James Morse , Jean-Philippe Brucker , Catalin Marinas , Will Deacon , Ingo Molnar , Borislav Petkov , Dave Hansen , Linuxarm , "justin.he@arm.com" , "jianyong.wu@arm.com" Subject: Re: [PATCH v6 06/16] ACPI: processor: Register deferred CPUs from acpi_processor_get_info() Message-ID: <20240417195730.00006ab5@Huawei.com> In-Reply-To: References: <20240417131909.7925-1-Jonathan.Cameron@huawei.com> <20240417131909.7925-7-Jonathan.Cameron@huawei.com> <22ace9b108ee488eb017f5b3e8facb8d@huawei.com> <20240417163842.0000415e@Huawei.com> <20240417180939.00003db7@huawei.com> Organization: Huawei Technologies Research and Development (UK) Ltd. X-Mailer: Claws Mail 4.1.0 (GTK 3.24.33; x86_64-w64-mingw32) Precedence: bulk X-Mailing-List: linux-arch@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-ClientProxiedBy: lhrpeml500001.china.huawei.com (7.191.163.213) To lhrpeml500005.china.huawei.com (7.191.163.240) On Wed, 17 Apr 2024 19:59:50 +0200 "Rafael J. Wysocki" wrote: > On Wed, Apr 17, 2024 at 7:09=E2=80=AFPM Jonathan Cameron > wrote: > > > > On Wed, 17 Apr 2024 17:59:36 +0200 > > "Rafael J. Wysocki" wrote: > > =20 > > > On Wed, Apr 17, 2024 at 5:38=E2=80=AFPM Jonathan Cameron > > > wrote: =20 > > > > > > > > On Wed, 17 Apr 2024 16:03:51 +0100 > > > > Salil Mehta wrote: > > > > =20 > > > > > > From: Jonathan Cameron > > > > > > Sent: Wednesday, April 17, 2024 2:19 PM > > > > > > > > > > > > From: James Morse > > > > > > > > > > > > The arm64 specific arch_register_cpu() call may defer CPU regi= stration until > > > > > > the ACPI interpreter is available and the _STA method can be e= valuated. > > > > > > > > > > > > If this occurs, then a second attempt is made in acpi_processo= r_get_info(). > > > > > > Note that the arm64 specific call has not yet been added so fo= r now this will > > > > > > be called for the original hotplug case. > > > > > > > > > > > > For architectures that do not defer until the ACPI Processor d= river loads > > > > > > (e.g. x86), for initially present CPUs there will already be a= CPU device. If > > > > > > present do not try to register again. > > > > > > > > > > > > Systems can still be booted with 'acpi=3Doff', or not include = an ACPI > > > > > > description at all as in these cases arch_register_cpu() will = not have > > > > > > deferred registration when first called. > > > > > > > > > > > > This moves the CPU register logic back to a subsys_initcall(),= while the > > > > > > memory nodes will have been registered earlier. > > > > > > Note this is where the call was prior to the cleanup series so= there should be > > > > > > no side effects of moving it back again for this specific case. > > > > > > > > > > > > [PATCH 00/21] Initial cleanups for vCPU HP. > > > > > > https://lore.kernel.org/all/ZVyz%2FVe5pPu8AWoA@shell.armlinux.= org.uk/ > > > > > > > > > > > > e.g. 5b95f94c3b9f ("x86/topology: Switch over to GENERIC_CPU_D= EVICES") > > > > > > > > > > > > Signed-off-by: James Morse > > > > > > Reviewed-by: Gavin Shan > > > > > > Tested-by: Miguel Luis > > > > > > Tested-by: Vishnu Pajjuri > > > > > > Tested-by: Jianyong Wu > > > > > > Signed-off-by: Russell King (Oracle) > > > > > > Co-developed-by: Jonathan Cameron > > > > > > Signed-off-by: Joanthan Cameron > > > > > > --- > > > > > > v6: Squash the two paths for conventional CPU Hotplug and arm64 > > > > > > vCPU HP. > > > > > > v5: Update commit message to make it clear this is moving the > > > > > > init back to where it was until very recently. > > > > > > > > > > > > No longer change the condition in the earlier registration= point > > > > > > as that will be handled by the arm64 registration routine > > > > > > deferring until called again here. > > > > > > --- > > > > > > drivers/acpi/acpi_processor.c | 12 +++++++++++- > > > > > > 1 file changed, 11 insertions(+), 1 deletion(-) > > > > > > > > > > > > diff --git a/drivers/acpi/acpi_processor.c b/drivers/acpi/acpi= _processor.c > > > > > > index 7ecb13775d7f..0cac77961020 100644 > > > > > > --- a/drivers/acpi/acpi_processor.c > > > > > > +++ b/drivers/acpi/acpi_processor.c > > > > > > @@ -356,8 +356,18 @@ static int acpi_processor_get_info(struct > > > > > > acpi_device *device) > > > > > > * > > > > > > * NOTE: Even if the processor has a cpuid, it may not be = present > > > > > > * because cpuid <-> apicid mapping is persistent now. > > > > > > + * > > > > > > + * Note this allows 3 flows, it is up to the arch_register= _cpu() > > > > > > + * call to reject any that are not supported on a given ar= chitecture. > > > > > > + * A) CPU becomes present. > > > > > > + * B) Previously invalid logical CPU ID (Same as becoming = present) > > > > > > + * C) CPU already present and now being enabled (and wasn't > > > > > > registered > > > > > > + * early on an arch that doesn't defer to here) > > > > > > */ > > > > > > - if (invalid_logical_cpuid(pr->id) || !cpu_present(pr->id)) { > > > > > > + if ((!invalid_logical_cpuid(pr->id) && cpu_present(pr->id) = && > > > > > > + !get_cpu_device(pr->id)) || > > > > > > + invalid_logical_cpuid(pr->id) || > > > > > > + !cpu_present(pr->id)) { =20 > > > > > > > > > > =20 > > > > Hi Salil, > > > > > > > > Thanks for quick review! > > > > =20 > > > > > Logic is clear but it is ugly. We should turn them into macro or = inline. =20 > > > > > > > > You've found the 'ugly' in this approach vs keeping them separate. > > > > > > > > For this version I wanted to keep it clear that indeed this conditi= on > > > > is a complex mess of different things (and to let people compare > > > > it easily with the two paths in v5 to convinced themselves this > > > > is the same) > > > > > > > > It's also a little tricky to do, so will need some thought. > > > > > > > > I don't think a simple acpi_cpu_is_hotplug() condition is useful > > > > as it just moves the complexity away from where a reader is looking > > > > and it would only be used in this one case. > > > > > > > > It doesn't separate well into finer grained subconditions because > > > > (C) is a messy case of the vCPU HP case and a not done > > > > something else earlier. The disadvantage of only deferring for > > > > arm64 and not other architectures. > > > > > > > > The best I can quickly come up with is something like this: > > > > #define acpi_cpu_not_present(cpu) \ > > > > (invalid_logical_cpuid(cpu) || !cpu_present(cpu)) > > > > #define acpi_cpu_not_enabled(cpu) \ > > > > (!invalid_logical_cpuid(cpu) || cpu_present(cpu)) > > > > > > > > if ((apci_cpu_not_enabled(pr->id) && !get_cpu_device(pr->id= ) || > > > > acpi_cpu_not_present(pr->id)) > > > > > > > > Which would still need the same amount of documentation. The > > > > code still isn't enough for me to immediately be able to see > > > > what is going on. > > > > > > > > So maybe worth it... I'm not sure. Rafael, you get to keep this > > > > fun, what would you prefer? =20 > > > > > > I would use a static inline function returning bool to carry out these > > > checks with comments explaining the different cases in which 'true' > > > needs to be returned. =20 > > > > The following makes a subtle logic change (I'll retest tomorrow) but > > I think that get_cpu_device(cpu) can never succeed in a path where > > hotadd makes sense. > > > > +/* > > + * Identify if the state transition indicates that hotadd_init > > + * should be called. > > + * > > + * For acpi_processor_add() to be called, the reported state must > > + * now be enabled and present. Conditions reflect prior state. > > + */ > > +static inline bool acpi_processor_should_hotadd_init(int cpu) > > +{ > > + /* Already register, initial registration was not deferred */ = =20 >=20 > "Already registered." I think. >=20 > > + if (get_cpu_device(cpu)) > > + return false; > > + > > + /* Processor has become present */ > > + if (!cpu_present(cpu)) > > + return true; > > + > > + /* Logical cpuid currently invalid indicates hotadd */ > > + if (invalid_logical_cpuid(cpu)) > > + return true; > > + > > + /* > > + * Previously present and the logical cpu id is valid. > > + * Deferred registration now _STA can be queries, or > > + * Hotadd due to enabled becoming true on an online capable > > + * CPU. > > + */ > > + if (cpu_present(cpu)) > > + return true; =20 >=20 > It returns true for both the cpu_present(cpu) and !cpu_present(cpu) > cases, so will it ever return false except for when > get_cpu_device(cpu) returns true? It indeed looks suspicious. My logic is probably wrong. Will check - I guess maybe pulling out the get_cpu_device(cpu) indeed flattens this as you point out. Kind of makes sense if true. Jonathan >=20 > > + > > + return false; > > +} > > + > > static int acpi_processor_get_info(struct acpi_device *device) > > { > > union acpi_object object =3D { 0 }; > > @@ -356,18 +388,8 @@ static int acpi_processor_get_info(struct acpi_dev= ice *device) > > * > > * NOTE: Even if the processor has a cpuid, it may not be pres= ent > > * because cpuid <-> apicid mapping is persistent now. > > - * > > - * Note this allows 3 flows, it is up to the arch_register_cpu= () > > - * call to reject any that are not supported on a given archit= ecture. > > - * A) CPU becomes present. > > - * B) Previously invalid logical CPU ID (Same as becoming pres= ent) > > - * C) CPU already present and now being enabled (and wasn't re= gistered > > - * early on an arch that doesn't defer to here) > > */ > > - if ((!invalid_logical_cpuid(pr->id) && cpu_present(pr->id) && > > - !get_cpu_device(pr->id)) || > > - invalid_logical_cpuid(pr->id) || > > - !cpu_present(pr->id)) { > > + if (acpi_processor_should_hotadd_init(pr->id)) { > > ret =3D acpi_processor_hotadd_init(pr, device); > > =20