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Subject: Re: [PATCH v6 10/34] x86, x86/mm, x86/xen, olpc: Use __va() against
 just the physical address in cr3
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From: Boris Ostrovsky <boris.ostrovsky@oracle.com>
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Date: Thu, 8 Jun 2017 17:17:29 -0400
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To: Tom Lendacky <thomas.lendacky@amd.com>, linux-arch@vger.kernel.org, linux-efi@vger.kernel.org, kvm@vger.kernel.org, linux-doc@vger.kernel.org, x86@kernel.org, kexec@lists.infradead.org, linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com, linux-mm@kvack.org, iommu@lists.linux-foundation.org
Cc: Brijesh Singh <brijesh.singh@amd.com>, Toshimitsu Kani <toshi.kani@hpe.com>, =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= <rkrcmar@redhat.com>, Matt Fleming <matt@codeblueprint.co.uk>, Alexander Potapenko <glider@google.com>, "H. Peter Anvin" <hpa@zytor.com>, Larry Woodman <lwoodman@redhat.com>, Jonathan Corbet <corbet@lwn.net>, Joerg Roedel <joro@8bytes.org>, "Michael S. Tsirkin" <mst@redhat.com>, Ingo Molnar <mingo@redhat.com>, Andrey Ryabinin <aryabinin@virtuozzo.com>, Dave Young <dyoung@redhat.com>, Rik van Riel <riel@redhat.com>, Arnd Bergmann <arnd@arndb.de>, Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>, Borislav Petkov <bp@alien8.de>, Andy Lutomirski <luto@kernel.org>, Thomas Gleixner <tglx@linutronix.de>, Dmitry Vyukov <dvyukov@google.com>, Juergen Gross <jgross@suse.com>, xen-devel <xen-devel@lists.xen.org>, Paolo Bonzini <pbonzini@redhat.com>

On 06/08/2017 05:02 PM, Tom Lendacky wrote:
> On 6/8/2017 3:51 PM, Boris Ostrovsky wrote:
>>
>>>
>>>> What may be needed is making sure X86_FEATURE_SME is not set for PV
>>>> guests.
>>>
>>> And that may be something that Xen will need to control through either
>>> CPUID or MSR support for the PV guests.
>>
>>
>> Only on newer versions of Xen. On earlier versions (2-3 years old) leaf
>> 0x80000007 is passed to the guest unchanged. And so is MSR_K8_SYSCFG.
>
> The SME feature is in leaf 0x8000001f, is that leaf passed to the guest
> unchanged?

Oh, I misread the patch where X86_FEATURE_SME is defined. Then all
versions, including the current one, pass it unchanged.

All that's needed is setup_clear_cpu_cap(X86_FEATURE_SME) in
xen_init_capabilities().


-boris

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