From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received-SPF: Pass (sender SPF authorized) identity=mailfrom; client-ip=66.187.233.73; helo=mx1.redhat.com; envelope-from=lersek@redhat.com; receiver=edk2-devel@lists.01.org Received: from mx1.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id DDCD620D7ADDB for ; Thu, 7 Jun 2018 10:15:04 -0700 (PDT) Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 14877401EF1B; Thu, 7 Jun 2018 17:15:04 +0000 (UTC) Received: from lacos-laptop-7.usersys.redhat.com (ovpn-121-78.rdu2.redhat.com [10.10.121.78]) by smtp.corp.redhat.com (Postfix) with ESMTP id 9E4B8728F5; Thu, 7 Jun 2018 17:15:02 +0000 (UTC) To: Ard Biesheuvel , edk2-devel@lists.01.org Cc: leif.lindholm@linaro.org, liming.gao@intel.com, michael.d.kinney@intel.com References: <20180607104645.22278-1-ard.biesheuvel@linaro.org> From: Laszlo Ersek Message-ID: <69346fc6-4b99-9fe9-0c60-3fc284f7a88c@redhat.com> Date: Thu, 7 Jun 2018 19:14:55 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 MIME-Version: 1.0 In-Reply-To: <20180607104645.22278-1-ard.biesheuvel@linaro.org> X-Scanned-By: MIMEDefang 2.79 on 10.11.54.5 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.5]); Thu, 07 Jun 2018 17:15:04 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.5]); Thu, 07 Jun 2018 17:15:04 +0000 (UTC) for IP:'10.11.54.5' DOMAIN:'int-mx05.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'lersek@redhat.com' RCPT:'' Subject: Re: [PATCH] MdePkg/BaseIoLibIntrinsic: make BaseIoLibIntrinsic safe for ArmVirt/KVM X-BeenThere: edk2-devel@lists.01.org X-Mailman-Version: 2.1.26 Precedence: list List-Id: EDK II Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 07 Jun 2018 17:15:05 -0000 Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit On 06/07/18 12:46, Ard Biesheuvel wrote: > KVM on ARM refuses to decode load/store instructions used to perform > I/O to emulated devices, and instead relies on the exception syndrome > information to describe the operand register, access size, etc. > This is only possible for instructions that have a single input/output > register (as opposed to ones that increment the offset register, or > load/store pair instructions, etc). Otherwise, QEMU crashes with the > following error > > error: kvm run failed Function not implemented > R00=01010101 R01=00000008 R02=00000048 R03=08000820 > R04=00000120 R05=7faaa0e0 R06=7faaa0dc R07=7faaa0e8 > R08=7faaa0ec R09=7faaa088 R10=000000ff R11=00000080 > R12=ff000000 R13=7fccfe08 R14=7faa835f R15=7faa887c > PSR=800001f3 N--- T svc32 > QEMU: Terminated > > and KVM produces a warning such as the following in the kernel log > > kvm [17646]: load/store instruction decoding not implemented > > The IoLib implementation provided by MdePkg/Library/BaseIoLibIntrinsic > is based on C code, and when LTO is in effect, the MMIO accesses could > be merged with, e.g., manipulations of the loop counter, producing > opcodes that KVM does not support for emulated MMIO. > > So let's add a special ArmVirt flavor of this library that implements > that actual load/store operations in assembler, ensuring that the > instructions involved can be emulated by KVM. > > Contributed-under: TianoCore Contribution Agreement 1.1 > Signed-off-by: Ard Biesheuvel > --- > ArmVirtPkg/ArmVirt.dsc.inc | 2 +- > MdePkg/Library/BaseIoLibIntrinsic/AArch64/ArmVirtMmio.S | 164 +++++ > MdePkg/Library/BaseIoLibIntrinsic/Arm/ArmVirtMmio.S | 161 +++++ > MdePkg/Library/BaseIoLibIntrinsic/Arm/ArmVirtMmio.asm | 165 +++++ > MdePkg/Library/BaseIoLibIntrinsic/BaseIoLibIntrinsicArmVirt.inf | 50 ++ > MdePkg/Library/BaseIoLibIntrinsic/IoLibArmVirt.c | 641 ++++++++++++++++++++ > 6 files changed, 1182 insertions(+), 1 deletion(-) Assuming Liming is OK with this patch for MdePkg, I have some comments (specific to adding this package to MdePkg): (1) ArmVirtPkg and MdePkg should likely not be modified in the same patch. (2) The library instance should be added as a standalone component to MdePkg.dsc (so it can be built without any client modules): [Components.ARM, Components.AARCH64] MdePkg/Library/BaseStackCheckLib/BaseStackCheckLib.inf MdePkg/Library/BaseIoLibIntrinsic/BaseIoLibIntrinsicArmVirt.inf <-HERE (3) Library instances under MdePkg are supposed to have MODULE_UNI_FILEs. I think customizing "BaseIoLibIntrinsic.uni" shouldn't be hard; it's basically a different format for re-stating the blurb of the new INF file. (Obviously, don't do anything about these until Liming follows up.) The rest looks OK to me! Thank you for this! Laszlo