linux-kernel - Re: [PATCH V1 3/6] xen/virtio: Add option to restrict memory access under Xen

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Message-ID: <e63bfa2c-6edb-f224-1d2a-0c69330492ad@oracle.com>
Date:   Sun, 24 Apr 2022 14:08:36 -0400
From:   Boris Ostrovsky <boris.ostrovsky@...cle.com>
To:     Oleksandr <olekstysh@...il.com>,
        Christoph Hellwig <hch@...radead.org>
Cc:     xen-devel@...ts.xenproject.org, x86@...nel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        Juergen Gross <jgross@...e.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Andy Lutomirski <luto@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        Stefano Stabellini <sstabellini@...nel.org>,
        Julien Grall <julien@....org>,
        Oleksandr Tyshchenko <oleksandr_tyshchenko@...m.com>,
        "Michael S. Tsirkin" <mst@...hat.com>
Subject: Re: [PATCH V1 3/6] xen/virtio: Add option to restrict memory access
 under Xen


On 4/24/22 12:53 PM, Oleksandr wrote:
>
> On 23.04.22 19:40, Christoph Hellwig wrote:
>
>
>
>
>>
>>> +
>>> +#ifdef CONFIG_ARCH_HAS_RESTRICTED_VIRTIO_MEMORY_ACCESS
>>> +int arch_has_restricted_virtio_memory_access(void)
>>> +{
>>> +    return (xen_has_restricted_virtio_memory_access() ||
>>> +            cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT));
>>> +}
>> So instead of hardcoding Xen here, this seems like a candidate for
>> another cc_platform_has flag.
>
>
> I have a limited knowledge of x86 and Xen on x86.
>
> Would the Xen specific bits fit into Confidential Computing Platform checks? I will let Juergen/Boris comment on this.
>

This is unrelated to confidential so I don't think we can add another CC_ flag.


Would arch/x86/kernel/cpu/hypervisor.c be a better home for this?


-boris