linux-kernel - Re: [PATCH v3 5/6] fs/core/vmcore: Move sev

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Message-ID: <20190718084416.GD24562@lst.de>
Date:   Thu, 18 Jul 2019 10:44:16 +0200
From:   Christoph Hellwig <hch@....de>
To:     Thiago Jung Bauermann <bauerman@...ux.ibm.com>
Cc:     x86@...nel.org, iommu@...ts.linux-foundation.org,
        linux-fsdevel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>, Christoph Hellwig <hch@....de>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Robin Murphy <robin.murphy@....com>,
        Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
        Alexey Dobriyan <adobriyan@...il.com>,
        Thomas Lendacky <Thomas.Lendacky@....com>,
        Halil Pasic <pasic@...ux.ibm.com>,
        Mike Anderson <andmike@...ux.ibm.com>,
        Ram Pai <linuxram@...ibm.com>
Subject: Re: [PATCH v3 5/6] fs/core/vmcore: Move sev_active() reference to
 x86 arch code

On Thu, Jul 18, 2019 at 12:28:57AM -0300, Thiago Jung Bauermann wrote:
> Secure Encrypted Virtualization is an x86-specific feature, so it shouldn't
> appear in generic kernel code because it forces non-x86 architectures to
> define the sev_active() function, which doesn't make a lot of sense.
> 
> To solve this problem, add an x86 elfcorehdr_read() function to override
> the generic weak implementation. To do that, it's necessary to make
> read_from_oldmem() public so that it can be used outside of vmcore.c.
> 
> Also, remove the export for sev_active() since it's only used in files that
> won't be built as modules.

I have to say I find the __weak overrides of the vmcore files very
confusing and which we'd have a better scheme there.  But as this fits
into that scheme and allows to remove the AMD SME vs SEV knowledge from
the core I'm fine with it.

Reviewed-by: Christoph Hellwig <hch@....de>