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Message-ID: <6ae2679c-e172-a955-9df5-2b54b79dd854@infradead.org>
Date: Mon, 8 Feb 2021 11:48:07 -0800
From: Randy Dunlap <rdunlap@...radead.org>
To: shuo.a.liu@...el.com, linux-kernel@...r.kernel.org, x86@...nel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
"H . Peter Anvin" <hpa@...or.com>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
Yu Wang <yu1.wang@...el.com>,
Reinette Chatre <reinette.chatre@...el.com>,
Zhi Wang <zhi.a.wang@...el.com>, Borislav Petkov <bp@...e.de>,
Dave Hansen <dave.hansen@...el.com>,
Sen Christopherson <sean.j.christopherson@...el.com>,
Dan Williams <dan.j.williams@...el.com>,
Fengwei Yin <fengwei.yin@...el.com>,
Zhenyu Wang <zhenyuw@...ux.intel.com>
Subject: Re: [PATCH v9 01/18] docs: acrn: Introduce ACRN
Hi--
On 2/6/21 7:10 PM, shuo.a.liu@...el.com wrote:
> From: Shuo Liu <shuo.a.liu@...el.com>
>
> Add documentation on the following aspects of ACRN:
>
> 1) A brief introduction on the architecture of ACRN.
> 2) I/O request handling in ACRN.
> 3) CPUID functions of ACRN.
> ---
> diff --git a/Documentation/virt/acrn/io-request.rst b/Documentation/virt/acrn/io-request.rst
> new file mode 100644
> index 000000000000..6cc3ea0fa1f5
> --- /dev/null
> +++ b/Documentation/virt/acrn/io-request.rst
> @@ -0,0 +1,97 @@
> +.. SPDX-License-Identifier: GPL-2.0
> +
> +I/O request handling
> +====================
> +
...
> +
> +1. I/O request
> +--------------
> +
> +For each User VM, there is a shared 4-KByte memory region used for I/O requests
> +communication between the hypervisor and Service VM. An I/O request is a
> +256-byte structure buffer, which is 'struct acrn_io_request', that is filled by
> +an I/O handler of the hypervisor when a trapped I/O access happens in a User
> +VM. ACRN userspace in the Service VM first allocates a 4-KByte page and passes
> +the GPA (Guest Physical Address) of the buffer to the hypervisor. The buffer is
> +used as an array of 16 I/O request slots with each I/O request slot being 256
> +bytes. This array is indexed by vCPU ID.
Does this mean that ACRN has a limit of 16 vCPUs ?
thanks.
--
~Randy
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