From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 03A19C4332F for ; Mon, 7 Nov 2022 18:01:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233006AbiKGSBM (ORCPT ); Mon, 7 Nov 2022 13:01:12 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38092 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232370AbiKGSAs (ORCPT ); Mon, 7 Nov 2022 13:00:48 -0500 Received: from mail-wr1-x436.google.com (mail-wr1-x436.google.com [IPv6:2a00:1450:4864:20::436]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EA6822B247 for ; Mon, 7 Nov 2022 09:56:51 -0800 (PST) Received: by mail-wr1-x436.google.com with SMTP id h9so17466712wrt.0 for ; Mon, 07 Nov 2022 09:56:51 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance-com.20210112.gappssmtp.com; s=20210112; h=mime-version:user-agent:message-id:date:references:subject:cc:to :from:from:to:cc:subject:date:message-id:reply-to; bh=T3PdXGFokMYHAAkilazNlYlaLTfFeBTny4nmc/XZVPA=; b=FY+QQ2oVQBn/h5WRmwrQ8ViPJMhpmfdXcqi0vbGJ7WFh3tGoRAQoi/nHcspbWFNR0A PKQeyeDw4mXPwCcwGN372L85lrk11rioa5/7ceojMnG1dpg2WETS8oY0bOVEC+QL8Btk 8XgRFX8mgqa0SZfsdazJwthY1uq1I0IWc0BWZo8HR+ccUnR7VyZTYi2QCM+DCsumhSjT vq7Pg3RgICwmwKW1Eb1MQhjC6YrUs/1nJZ5bLbIoh//dnZxm6y9O6YOa7qkseonvz0qg vxXBmLH1lXeiLyu0lHLoPf8VGJ3pyoHszBGKLsnqejccRqrdxMV5cVpe6Sxjn91mAW5u WvDA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=mime-version:user-agent:message-id:date:references:subject:cc:to :from:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=T3PdXGFokMYHAAkilazNlYlaLTfFeBTny4nmc/XZVPA=; b=KvhJvH/ZD+sv5ffviM5FxpKhLghmmVyvHYy3HtlfyWWuX+9qG96fj9hsGXaSFT4gIh XnhIYuANVYUSoUV7cmwD0BpcwlLAapfaLLXoaRD9MgRpbX58b6b48ue7xq3FZNpmQ1NW apvrwC+jkBGcNkvvD4br+Z/CLWXpCGKC+w6sDL+xDC7SY02rKLOpSzHOR5TuN30nGT50 DmJOmGqAtBJPvevRQ99d0HjfBUZZ7JlwvMohs9PnZIJJmHbM8jr2XxO5NSsJ2UDV91ru xCCqXVOgnwO3j0hfrWovaDLPmcDu5QMd0mCPE6UTJTONjg7nETUA1DD+JH8VjrVsYxh7 6wnw== X-Gm-Message-State: ACrzQf1bp/pfpRXZ8uHCsVborU3iUgZ8PfcBJSrhseMZExQtckpdVFt3 NENUvs8pnwsjrLN4Zi280tOVNA== X-Google-Smtp-Source: AMsMyM5L4/wnYoqPY7Lfe0ZxjSlXO8kmalMHRqh/UMafMsHtZVAmgq/s4+7IjonnmIgORkq9EHznsg== X-Received: by 2002:a05:6000:1841:b0:236:70dc:1a6f with SMTP id c1-20020a056000184100b0023670dc1a6fmr32784664wri.464.1667843810520; Mon, 07 Nov 2022 09:56:50 -0800 (PST) Received: from localhost ([95.148.15.66]) by smtp.gmail.com with ESMTPSA id v4-20020a5d4a44000000b002365254ea42sm8079706wrs.1.2022.11.07.09.56.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 07 Nov 2022 09:56:49 -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 1/6] KVM: arm64: Document PV-lock interface References: <20221104062105.4119003-1-usama.arif@bytedance.com> <20221104062105.4119003-2-usama.arif@bytedance.com> Date: Mon, 07 Nov 2022 17:56:49 +0000 Message-ID: <87k0463axq.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 Hi Usama, Usama Arif writes: > Introduce a paravirtualization interface for KVM/arm64 to obtain whether > the VCPU is currently running or not. > > The PV lock structure of the guest is allocated by user space. > > A hypercall interface is provided for the guest to interrogate the > location of the shared memory structures. > > Signed-off-by: Zengruan Ye > Signed-off-by: Usama Arif > --- > Documentation/virt/kvm/arm/index.rst | 1 + > Documentation/virt/kvm/arm/pvlock.rst | 52 +++++++++++++++++++++++++ > Documentation/virt/kvm/devices/vcpu.rst | 25 ++++++++++++ > 3 files changed, 78 insertions(+) > create mode 100644 Documentation/virt/kvm/arm/pvlock.rst > > diff --git a/Documentation/virt/kvm/arm/index.rst b/Documentation/virt/kvm/arm/index.rst > index e84848432158..b8499dc00a6a 100644 > --- a/Documentation/virt/kvm/arm/index.rst > +++ b/Documentation/virt/kvm/arm/index.rst > @@ -10,4 +10,5 @@ ARM > hyp-abi > hypercalls > pvtime > + pvlock > ptp_kvm > diff --git a/Documentation/virt/kvm/arm/pvlock.rst b/Documentation/virt/kvm/arm/pvlock.rst > new file mode 100644 > index 000000000000..d3c391b16d36 > --- /dev/null > +++ b/Documentation/virt/kvm/arm/pvlock.rst > @@ -0,0 +1,52 @@ > +.. SPDX-License-Identifier: GPL-2.0 > + > +Paravirtualized lock support for arm64 > +====================================== > + > +KVM/arm64 provides a hypervisor service call for paravirtualized guests to > +determine whether a VCPU is currently running or not. > + > +A new SMCCC compatible hypercall is defined: > + > +* ARM_SMCCC_VENDOR_HYP_KVM_PV_LOCK_FUNC_ID: 0xC6000002 > + > +ARM_SMCCC_VENDOR_HYP_KVM_PV_LOCK_FUNC_ID > + > + ============= ======== ========================================== > + Function ID: (uint32) 0xC6000002 > + Return value: (int64) IPA of the pv lock data structure for this > + VCPU. On failure: > + NOT_SUPPORTED (-1) > + ============= ======== ========================================== > + > +The IPA returned by PV_LOCK_PREEMPTED should be mapped by the guest as normal > +memory with inner and outer write back caching attributes, in the inner > +shareable domain. > + > +PV_LOCK_PREEMPTED returns the structure for the calling VCPU. > + > +PV lock state > +------------- > + > +The structure pointed to by the PV_LOCK_PREEMPTED hypercall is as follows: > + > ++-----------+-------------+-------------+---------------------------------+ > +| Field | Byte Length | Byte Offset | Description | > ++===========+=============+=============+=================================+ > +| preempted | 8 | 0 | Indicate if the VCPU that owns | > +| | | | this struct is running or not. | > +| | | | Non-zero values mean the VCPU | > +| | | | has been preempted. Zero means | > +| | | | the VCPU is not preempted. | > ++-----------+-------------+-------------+---------------------------------+ > + > +The preempted field will be updated to 1 by the hypervisor prior to scheduling > +a VCPU. When the VCPU is scheduled out, the preempted field will be updated > +to 0 by the hypervisor. The text above doesn't match the description in the table. Please update the texts to align them with the code. [...]