From patchwork Fri Mar 15 08:11:04 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: bibo mao X-Patchwork-Id: 13593155 Received: from mail.loongson.cn (mail.loongson.cn [114.242.206.163]) by smtp.subspace.kernel.org (Postfix) with ESMTP id D5E3C1429B; Fri, 15 Mar 2024 08:11:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=114.242.206.163 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1710490270; cv=none; b=kgFu6FfV4OXy9q8SeWccIm35XcQPPTlr+SgOmBkZKvN5r2aaALHzDsUg7pzhsT1I+9cK2eBdhGWzbJRgiE9XdAEnQkGK5k0gu7CIMa5MWW/cs1VHlL9DrKWzP07WMmxn4Uq9Jw+uM4Y5l6TQhwZR4ksMoig7nMteG5jfm3bD7z0= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1710490270; c=relaxed/simple; bh=pXqz4qetKcexyld6lqrWVua3KVrcp3aKmnVf9vX3cr0=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=kJ72fEkXD1uaf+jxI1QycHm3cVQgC+e+FRv1Sx7lkF6p/WYO7qy+6v12ENfhoJ+ngCKbsWSKNRzJo+ZMeIE6AChCOrZPlp/XlfiapYeyZKcQkOrJU0uHqIi1tTrwEnk1HfUOxb6qHFQDWdWSLSZWxDApEtKky/RmvP52RxzQ1D0= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=loongson.cn; spf=pass smtp.mailfrom=loongson.cn; arc=none smtp.client-ip=114.242.206.163 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=loongson.cn Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=loongson.cn Received: from loongson.cn (unknown [10.2.5.213]) by gateway (Coremail) with SMTP id _____8AxeeiZAvRlAmYZAA--.41874S3; Fri, 15 Mar 2024 16:11:05 +0800 (CST) Received: from localhost.localdomain (unknown [10.2.5.213]) by localhost.localdomain (Coremail) with SMTP id AQAAf8DxfROYAvRlv8haAA--.9838S2; Fri, 15 Mar 2024 16:11:04 +0800 (CST) From: Bibo Mao To: Huacai Chen , Tianrui Zhao , WANG Xuerui , Juergen Gross , Paolo Bonzini , Jonathan Corbet Cc: loongarch@lists.linux.dev, linux-kernel@vger.kernel.org, virtualization@lists.linux.dev, kvm@vger.kernel.org Subject: [PATCH v7 7/7] Documentation: KVM: Add hypercall for LoongArch Date: Fri, 15 Mar 2024 16:11:04 +0800 Message-Id: <20240315081104.2813031-1-maobibo@loongson.cn> X-Mailer: git-send-email 2.39.3 In-Reply-To: <20240315080710.2812974-1-maobibo@loongson.cn> References: <20240315080710.2812974-1-maobibo@loongson.cn> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-CM-TRANSID: AQAAf8DxfROYAvRlv8haAA--.9838S2 X-CM-SenderInfo: xpdruxter6z05rqj20fqof0/ X-Coremail-Antispam: 1Uk129KBj93XoWxAFWUury5tw15XF47Kw1ktFc_yoWrtr4rpF 95G3s7Grn7Jry7A347JF1UXryYkryxJF47Ga18Jr1Fqr1Dtr1fJr4UtFyYy3W8G3y8AFy8 XF1Iqr1j9r1UAwcCm3ZEXasCq-sJn29KB7ZKAUJUUUUx529EdanIXcx71UUUUU7KY7ZEXa sCq-sGcSsGvfJ3Ic02F40EFcxC0VAKzVAqx4xG6I80ebIjqfuFe4nvWSU5nxnvy29KBjDU 0xBIdaVrnRJUUUBvb4IE77IF4wAFF20E14v26r1j6r4UM7CY07I20VC2zVCF04k26cxKx2 IYs7xG6rWj6s0DM7CIcVAFz4kK6r1Y6r17M28lY4IEw2IIxxk0rwA2F7IY1VAKz4vEj48v e4kI8wA2z4x0Y4vE2Ix0cI8IcVAFwI0_Ar0_tr1l84ACjcxK6xIIjxv20xvEc7CjxVAFwI 0_Cr0_Gr1UM28EF7xvwVC2z280aVAFwI0_Gr1j6F4UJwA2z4x0Y4vEx4A2jsIEc7CjxVAF wI0_Gr1j6F4UJwAaw2AFwI0_JF0_Jw1le2I262IYc4CY6c8Ij28IcVAaY2xG8wAqjxCEc2 xF0cIa020Ex4CE44I27wAqx4xG64xvF2IEw4CE5I8CrVC2j2WlYx0E2Ix0cI8IcVAFwI0_ Wrv_ZF1lYx0Ex4A2jsIE14v26F4j6r4UJwAm72CE4IkC6x0Yz7v_Jr0_Gr1lF7xvr2IYc2 Ij64vIr41lc7CjxVAaw2AFwI0_JF0_Jw1l42xK82IYc2Ij64vIr41l4I8I3I0E4IkC6x0Y z7v_Jr0_Gr1l4IxYO2xFxVAFwI0_JF0_Jw1lx2IqxVAqx4xG67AKxVWUJVWUGwC20s026x 8GjcxK67AKxVWUGVWUWwC2zVAF1VAY17CE14v26r1q6r43MIIYrxkI7VAKI48JMIIF0xvE 2Ix0cI8IcVAFwI0_Ar0_tr1lIxAIcVC0I7IYx2IY6xkF7I0E14v26F4j6r4UJwCI42IY6x AIw20EY4v20xvaj40_Jr0_JF4lIxAIcVC2z280aVAFwI0_Cr0_Gr1UMIIF0xvEx4A2jsIE c7CjxVAFwI0_Gr0_Gr1UYxBIdaVFxhVjvjDU0xZFpf9x07jxxhdUUUUU= Add documentation topic for using pv_virt when running as a guest on KVM hypervisor. Signed-off-by: Bibo Mao --- Documentation/virt/kvm/index.rst | 1 + .../virt/kvm/loongarch/hypercalls.rst | 82 +++++++++++++++++++ Documentation/virt/kvm/loongarch/index.rst | 10 +++ 3 files changed, 93 insertions(+) create mode 100644 Documentation/virt/kvm/loongarch/hypercalls.rst create mode 100644 Documentation/virt/kvm/loongarch/index.rst diff --git a/Documentation/virt/kvm/index.rst b/Documentation/virt/kvm/index.rst index ad13ec55ddfe..9ca5a45c2140 100644 --- a/Documentation/virt/kvm/index.rst +++ b/Documentation/virt/kvm/index.rst @@ -14,6 +14,7 @@ KVM s390/index ppc-pv x86/index + loongarch/index locking vcpu-requests diff --git a/Documentation/virt/kvm/loongarch/hypercalls.rst b/Documentation/virt/kvm/loongarch/hypercalls.rst new file mode 100644 index 000000000000..0f61a49c31a9 --- /dev/null +++ b/Documentation/virt/kvm/loongarch/hypercalls.rst @@ -0,0 +1,82 @@ +.. SPDX-License-Identifier: GPL-2.0 + +=================================== +The LoongArch paravirtual interface +=================================== + +KVM hypercalls use the HVCL instruction with code 0x100, and the hypercall +number is put in a0 and up to five arguments may be placed in a1-a5, the +return value is placed in a0. + +The code for that interface can be found in arch/loongarch/kvm/* + +Querying for existence +====================== + +To find out if we're running on KVM or not, cpucfg can be used with index +CPUCFG_KVM_BASE (0x40000000), cpucfg range between 0x40000000 - 0x400000FF +is marked as a specially reserved range. All existing and future processors +will not implement any features in this range. + +When Linux is running on KVM, cpucfg with index CPUCFG_KVM_BASE (0x40000000) +returns magic string "KVM\0" + +Once you determined you're running under a PV capable KVM, you can now use +hypercalls described as follows. + +KVM hypercall ABI +================= + +Hypercall ABI on KVM is simple, only one scratch register a0 and at most +five generic registers used as input parameter. FP register and vector register +is not used for input register and should not be modified during hypercall. +Hypercall function can be inlined since there is only one scratch register. + +The parameters are as follows: + + ======== ========================= ===================== + Register IN OUT + ======== ========================= ===================== + a0 function number(Required) Return code(Required) + a1 1st parameter(Optional) Keep Unmodified + a2 2nd parameter(Optional) Keep Unmodified + a3 3rd parameter(Optional) Keep Unmodified + a4 4th parameter(Optional) Keep Unmodified + a5 5th parameter(Optional) Keep Unmodified + ======== ========================= ===================== + +Return codes can be as follows: + + ==== ========================= + Code Meaning + ==== ========================= + 0 Success + -1 Hypercall not implemented + -2 Hypercall parameter error + ==== ========================= + +KVM Hypercalls Documentation +============================ + +The template for each hypercall is: +1. Hypercall name +2. Purpose + +1. KVM_HCALL_FUNC_PV_IPI +------------------------ + +:Purpose: Send IPIs to multiple vCPUs. + +- a0: KVM_HCALL_FUNC_PV_IPI +- a1: lower part of the bitmap of destination physical cpu core id +- a2: higher part of the bitmap of destination physical cpu core id +- a3: the lowest physical cpu core id in bitmap + +The hypercall lets a guest send multicast IPIs, with at most 128 +destinations per hypercall. The destinations are represented by a bitmap +contained in the first two arguments (a1 and a2). Bit 0 of a1 corresponds +to the physical cpu core id in the third argument (a3), bit 1 corresponds +to the physical cpu core id a3+1, and so on. + +Returns success always, it skips current cpu and continues to send ipi to +next cpu in the bitmap mask if current physical cpu core id is invalid. diff --git a/Documentation/virt/kvm/loongarch/index.rst b/Documentation/virt/kvm/loongarch/index.rst new file mode 100644 index 000000000000..83387b4c5345 --- /dev/null +++ b/Documentation/virt/kvm/loongarch/index.rst @@ -0,0 +1,10 @@ +.. SPDX-License-Identifier: GPL-2.0 + +========================= +KVM for LoongArch systems +========================= + +.. toctree:: + :maxdepth: 2 + + hypercalls.rst