linux-kernel - Re: [PATCH v6 25/34] swiotlb: Add warnings for use of bounce buffers with SME

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Date:   Thu, 15 Jun 2017 08:23:17 -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 v6 25/34] swiotlb: Add warnings for use of bounce buffers
 with SME

On 6/15/2017 4:08 AM, Borislav Petkov wrote:
> On Wed, Jun 14, 2017 at 02:49:02PM -0500, Tom Lendacky wrote:
>> I guess I don't need the sme_active() check since the second part of the
>> if statement can only ever be true if SME is active (since mask is
>> unsigned).
> 
> ... and you can define sme_me_mask as an u64 directly (it is that already,
> practically, as we don't do SME on 32-bit) and then get rid of the cast.

Let me look into that. There are so many places that are expecting an
unsigned long I'll have to see how that all works out from a build
perspective.

Thanks,
Tom

>