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

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Message-ID: <22a6eb7e-f98c-ff15-f4dd-b2834ad345c8@suse.com>
Date:   Mon, 25 Apr 2022 09:53:23 +0200
From:   Juergen Gross <jgross@...e.com>
To:     Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        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,
        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 24.04.22 20:08, Boris Ostrovsky wrote:
> 
> 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?

Or a callback in struct struct x86_hyper_runtime maybe?


Juergen

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