From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by mx.groups.io with SMTP id smtpd.web11.9709.1633601024549704589 for ; Thu, 07 Oct 2021 03:03:44 -0700 Authentication-Results: mx.groups.io; dkim=pass header.i=@kernel.org header.s=k20201202 header.b=K9CRvwa4; spf=pass (domain: kernel.org, ip: 198.145.29.99, mailfrom: ardb@kernel.org) Received: by mail.kernel.org (Postfix) with ESMTPSA id BEAAA611C3; Thu, 7 Oct 2021 10:03:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1633601022; bh=M+SDH8vkCjk3chY7gj3RyiNH0rYE2K6d9rsymarZ1Gw=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=K9CRvwa4xnC22GI8qlIPIsOEroc/UpQIn0UyXkjU4QPw5q5Pl3T78fNJIDN07Uf3j 4XTBgRQMgY9zaPmkYbVZj3S5l82yGEZUDCkKU7tRcLXwtwkrKJ0CyIhxJ6RWW8Nric zBoYuI2ky2b3A+i1RQ1E0LgzyNIkmqoXvqYwJW6pzgaOQm6vqHpE5VRdCobmxKprl7 R3yMWMxbtq07gll6S89r4mRzsQ6xYd+wkfUZhv5FaG1T1NuueWBJo0fEwxlw3rYo9n yJS0silk1tB7xVEEeoeVWGV433/Up4r0psB3sV4UJFdg+kFyINzxsjqOUrQR9MfaWe rXLzvsLk728QA== Received: by mail-ot1-f53.google.com with SMTP id l7-20020a0568302b0700b0054e40740571so1139868otv.0; Thu, 07 Oct 2021 03:03:42 -0700 (PDT) X-Gm-Message-State: AOAM531T0xcQcn6nt03pTsx0SVzsN/EMdmvCuoyRr7WoKx60LdKlExK9 8BgcoLmWtl9Jb5bVZLTEHqj4lpIF0mdQn7EYcKo= X-Google-Smtp-Source: ABdhPJyNZ1aplx1GF8QENoiMW9pqF9yTXnHZIooclknUXd5WX8OCu/cBsOwoXniF0Cb3+ty00xNkuEw3edIEjHvSREY= X-Received: by 2002:a05:6830:3189:: with SMTP id p9mr2714325ots.147.1633601022130; Thu, 07 Oct 2021 03:03:42 -0700 (PDT) MIME-Version: 1.0 References: <20210925021752.20678-1-rebecca@nuviainc.com> <20210928111435.poztq4cksagsogbw@leviathan> <20211007094125.soldrzx7wfoa5kyw@leviathan> In-Reply-To: <20211007094125.soldrzx7wfoa5kyw@leviathan> From: "Ard Biesheuvel" Date: Thu, 7 Oct 2021 12:03:30 +0200 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [RFC] [PATCH 0/2] Proposal to add EFI_MP_SERVICES_PROTOCOL support for AARCH64 To: Leif Lindholm Cc: Ard Biesheuvel , Sami Mujawar , edk2-devel-groups-io , Rebecca Cran , Gerd Hoffmann , edk2 RFC list Content-Type: text/plain; charset="UTF-8" On Thu, 7 Oct 2021 at 11:41, Leif Lindholm wrote: > > Ard/Sami - any comments? > The code changes by itself look fine to me. The only problem I see is that we cannot run arbitrary code on other cores with the MMU off, given that in that case, they don't comply with the UEFI AArch64 platform requirements, most notably the one that says that unaligned accesses must be permitted. So either we severely constrain the kind of code that we permit to run on other cores, or we enable the MMU and caches on each core as it comes out of reset, as well as do any other CPU specific initialization that we do for the primary core as well. > > On Tue, Sep 28, 2021 at 12:14:35 +0100, Leif Lindholm wrote: > > On Fri, Sep 24, 2021 at 20:17:50 -0600, Rebecca Cran wrote: > > > I'd like to propose adding EFI_MP_SERVICES_PROTOCOL support for > > > AARCH64 systems. I've attached two patches to implement support for it > > > in the DXE phase, based on code in EmulatorPkg and UefiCpuPkg. It's added > > > under ArmPkg for now, but longer term it should probably be moved into > > > UefiCpuPkg. > > > > > > Patch 1/2 is the start of addressing the issue that the Aff0 field of > > > the MPIDR is no longer guaranteed to be the core, and should be referred > > > to in a more generic way: for example it could be the thread, with Aff1 > > > being the core and Aff2 the cluster. Clearly much more work is needed > > > to fully remove that assumption. > > > > Just to add to this: > > Aff0 was never defined by the architecture to be the "core", it was > > just the smallest schedulable entity. The intent being that whether > > you had multiple hardware threads per core or not, you could just use > > the affinity to determine whether > > There is also a bit in the MPIDR to indicate whether the core *had* > > multiple hardware threads. > > > > In recent processors (without any change to the architecture), ARM > > thought it would be beneficial to keep software developers on their > > toes by starting to use the hyperthreading layout even for processors > > without hyperthreading support. I.e. Aff0 is always 0 even though MT > > is 0: > > https://developer.arm.com/documentation/100798/0301/Register-descriptions/AArch64-system-registers/MPIDR-EL1--Multiprocessor-Affinity-Register--EL1 > > The justification being that an SoC might contain both processors > > with and without multiple hardware threads per core. > > > > Anyway, the point is that from at least Cortex-A76 onwards, Aff0 no > > longer maps to CoreId universally, and Aff1 no longer maps to > > ClusterId, for all non-threaded implementations. > > So we need to start cleaning up this use. > > This will possibly break some out-of-tree platforms, but I figure > > we're far enough from next stable tag for that not to matter too > > much. > > > > > Patch 2/2 implements the EFI_MP_SERVICES_PROTOCOL for DXE in Library/MpInitLib. > > > > Worth calling out in the cover letter that this is backed by PSCI. > > > > / > > Leif > > > > > CpuDxe initializes the MP support, and as a result gains a dependency on > > > MpInitLib. ArmVirt.dsc.inc needs updated to add the new library, as will > > > all AARCH64 platforms. > > > > > > I sent out a patch for MdeModulePkg last week to add a corresponding test > > > application, MpServicesTest (see https://edk2.groups.io/g/devel/message/80878). > > > > > > Rebecca Cran (2): > > > ArmPkg: Replace CoreId and ClusterId with Mpidr in ARM_CORE_INFO > > > struct > > > ArmPkg: Add Library/MpInitLib to support EFI_MP_SERVICES_PROTOCOL > > > > > > ArmPkg/ArmPkg.dec | 4 + > > > ArmPkg/ArmPkg.dsc | 4 + > > > ArmPkg/Drivers/CpuDxe/AArch64/Arch.c | 22 + > > > ArmPkg/Drivers/CpuDxe/Arm/Arch.c | 22 + > > > ArmPkg/Drivers/CpuDxe/CpuDxe.c | 2 + > > > ArmPkg/Drivers/CpuDxe/CpuDxe.h | 10 + > > > ArmPkg/Drivers/CpuDxe/CpuDxe.inf | 6 + > > > ArmPkg/Drivers/CpuDxe/CpuMpInit.c | 604 ++++++++ > > > ArmPkg/Include/Guid/ArmMpCoreInfo.h | 3 +- > > > ArmPkg/Include/Library/ArmLib.h | 4 + > > > ArmPkg/Include/Library/MpInitLib.h | 366 +++++ > > > ArmPkg/Library/MpInitLib/AArch64/MpFuncs.S | 61 + > > > ArmPkg/Library/MpInitLib/DxeMpInitLib.inf | 53 + > > > ArmPkg/Library/MpInitLib/DxeMpLib.c | 1498 ++++++++++++++++++++ > > > ArmPkg/Library/MpInitLib/InternalMpInitLib.h | 358 +++++ > > > ArmPlatformPkg/Library/ArmPlatformLibNull/ArmPlatformLibNull.c | 8 +- > > > ArmPlatformPkg/PrePeiCore/MainMPCore.c | 2 +- > > > ArmPlatformPkg/PrePi/MainMPCore.c | 2 +- > > > ArmVirtPkg/ArmVirt.dsc.inc | 3 + > > > 19 files changed, 3024 insertions(+), 8 deletions(-) > > > create mode 100644 ArmPkg/Drivers/CpuDxe/AArch64/Arch.c > > > create mode 100644 ArmPkg/Drivers/CpuDxe/Arm/Arch.c > > > create mode 100644 ArmPkg/Drivers/CpuDxe/CpuMpInit.c > > > create mode 100644 ArmPkg/Include/Library/MpInitLib.h > > > create mode 100644 ArmPkg/Library/MpInitLib/AArch64/MpFuncs.S > > > create mode 100644 ArmPkg/Library/MpInitLib/DxeMpInitLib.inf > > > create mode 100644 ArmPkg/Library/MpInitLib/DxeMpLib.c > > > create mode 100644 ArmPkg/Library/MpInitLib/InternalMpInitLib.h > > > > > > -- > > > 2.31.1 > > >