linux-kernel - Re: [PATCH v5 28/32] x86/mm, kexec: Allow kexec to be used with SME

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Date:   Fri, 19 May 2017 16:07:24 -0500
From:   Tom Lendacky <thomas.lendacky@....com>
To:     Borislav Petkov <bp@...en8.de>
CC:     <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>,
        Rik van Riel <riel@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Toshimitsu Kani <toshi.kani@....com>,
        Arnd Bergmann <arnd@...db.de>,
        Jonathan Corbet <corbet@....net>,
        Matt Fleming <matt@...eblueprint.co.uk>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Joerg Roedel <joro@...tes.org>,
        Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Larry Woodman <lwoodman@...hat.com>,
        Brijesh Singh <brijesh.singh@....com>,
        Ingo Molnar <mingo@...hat.com>,
        Andy Lutomirski <luto@...nel.org>,
        "H. Peter Anvin" <hpa@...or.com>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Alexander Potapenko <glider@...gle.com>,
        Dave Young <dyoung@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Dmitry Vyukov <dvyukov@...gle.com>
Subject: Re: [PATCH v5 28/32] x86/mm, kexec: Allow kexec to be used with SME

On 5/19/2017 3:58 PM, Borislav Petkov wrote:
> On Fri, May 19, 2017 at 03:45:28PM -0500, Tom Lendacky wrote:
>> Actually there is.  The above will result in data in the cache because
>> halt() turns into a function call if CONFIG_PARAVIRT is defined (refer
>> to the comment above where do_wbinvd_halt is set to true). I could make
>> this a native_wbinvd() and native_halt()
>
> That's why we have the native_* versions - to bypass paravirt crap.

As long as those never change from static inline everything will be
fine. I can change it, but I really like how it explicitly indicates
what is needed in this case. Even if the function gets changed from
static inline the fact that the instructions are sequential in the
function covers that case.

Thanks,
Tom

>