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Mon, 07 Nov 2022 09:58:03 -0800 (PST) Received: from localhost ([95.148.15.66]) by smtp.gmail.com with ESMTPSA id n17-20020a5d6611000000b002383edcde09sm7994811wru.59.2022.11.07.09.58.02 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 07 Nov 2022 09:58:02 -0800 (PST) From: Punit Agrawal To: Usama Arif Cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, linux-doc@vger.kernel.org, virtualization@lists.linux-foundation.org, linux@armlinux.org.uk, yezengruan@huawei.com, catalin.marinas@arm.com, will@kernel.org, maz@kernel.org, steven.price@arm.com, mark.rutland@arm.com, bagasdotme@gmail.com, fam.zheng@bytedance.com, liangma@liangbit.com, punit.agrawal@bytedance.com Subject: Re: [v2 2/6] KVM: arm64: Add SMCCC paravirtualised lock calls References: <20221104062105.4119003-1-usama.arif@bytedance.com> <20221104062105.4119003-3-usama.arif@bytedance.com> Date: Mon, 07 Nov 2022 17:58:01 +0000 Message-ID: <87cz9y3avq.fsf@stealth> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org Usama Arif writes: > Add a new SMCCC compatible hypercalls for PV lock features: > ARM_SMCCC_KVM_FUNC_PV_LOCK: 0xC6000002 > > Also add the header file which defines the ABI for the paravirtualized > lock features we're about to add. > > Signed-off-by: Zengruan Ye > Signed-off-by: Usama Arif > --- > arch/arm64/include/asm/pvlock-abi.h | 17 +++++++++++++++++ > include/linux/arm-smccc.h | 8 ++++++++ > tools/include/linux/arm-smccc.h | 8 ++++++++ > 3 files changed, 33 insertions(+) > create mode 100644 arch/arm64/include/asm/pvlock-abi.h > > diff --git a/arch/arm64/include/asm/pvlock-abi.h b/arch/arm64/include/asm/pvlock-abi.h > new file mode 100644 > index 000000000000..3f4574071679 > --- /dev/null > +++ b/arch/arm64/include/asm/pvlock-abi.h > @@ -0,0 +1,17 @@ > +/* SPDX-License-Identifier: GPL-2.0 */ > +/* > + * Copyright(c) 2019 Huawei Technologies Co., Ltd > + * Author: Zengruan Ye > + * Usama Arif > + */ > + > +#ifndef __ASM_PVLOCK_ABI_H > +#define __ASM_PVLOCK_ABI_H > + > +struct pvlock_vcpu_state { > + __le64 preempted; > + /* Structure must be 64 byte aligned, pad to that size */ > + u8 padding[56]; > +} __packed; For structure alignment, I'd have expected to see the use of "aligned" attribute. Is there any benefit in using padding to achieve alignment? [...]