linux-kernel - Re: [Xen-devel] [PATCH v6 10/34] x86, x86/mm, x86/xen, olpc: Use __va() against just the physical address in cr3

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Message-ID: <d1931930-78d6-ebb1-755c-80bc88a397ed@oracle.com>
Date:   Fri, 9 Jun 2017 15:42:24 -0400
From:   Boris Ostrovsky <boris.ostrovsky@...cle.com>
To:     Tom Lendacky <thomas.lendacky@....com>,
        Andrew Cooper <andrew.cooper3@...rix.com>,
        linux-arch@...r.kernel.org, linux-efi@...r.kernel.org,
        kvm@...r.kernel.org, linux-doc@...r.kernel.org, x86@...nel.org,
        kexec@...ts.infradead.org, linux-kernel@...r.kernel.org,
        kasan-dev@...glegroups.com, linux-mm@...ck.org,
        iommu@...ts.linux-foundation.org
Cc:     Brijesh Singh <brijesh.singh@....com>,
        Toshimitsu Kani <toshi.kani@....com>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Matt Fleming <matt@...eblueprint.co.uk>,
        Alexander Potapenko <glider@...gle.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Larry Woodman <lwoodman@...hat.com>,
        Jonathan Corbet <corbet@....net>,
        Joerg Roedel <joro@...tes.org>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Ingo Molnar <mingo@...hat.com>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Dave Young <dyoung@...hat.com>, Rik van Riel <riel@...hat.com>,
        Arnd Bergmann <arnd@...db.de>, Borislav Petkov <bp@...en8.de>,
        Andy Lutomirski <luto@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Juergen Gross <jgross@...e.com>,
        xen-devel <xen-devel@...ts.xen.org>,
        Paolo Bonzini <pbonzini@...hat.com>
Subject: Re: [Xen-devel] [PATCH v6 10/34] x86, x86/mm, x86/xen, olpc: Use
 __va() against just the physical address in cr3


>>
>> PV guests don't go through Linux x86 early boot code. They start at
>> xen_start_kernel() (well, xen-head.S:startup_xen(), really) and  merge
>> with baremetal path at x86_64_start_reservations() (for 64-bit).
>>
>
> Ok, I don't think anything needs to be done then. The sme_me_mask is set
> in sme_enable() which is only called from head_64.S. If the sme_me_mask
> isn't set then SME won't be active. The feature will just report the
> capability of the processor, but that doesn't mean it is active. If you
> still want the feature to be clobbered we can do that, though.

I'd prefer to explicitly clear to avoid any ambiguity.

-boris