linux-kernel - Re: [PATCH v5 06/14] x86/ioremap: Support hypervisor specified range to map as encrypted

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Date:   Thu, 9 Mar 2023 12:59:37 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     David Woodhouse <dwmw2@...radead.org>,
        "thomas.lendacky@....com" <thomas.lendacky@....com>,
        Jörg Rödel <joro@...tes.org>
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Subject: Re: [PATCH v5 06/14] x86/ioremap: Support hypervisor specified range
 to map as encrypted

First of all,

thanks for proactively pointing that out instead of simply using what's
there and we get to find out later, only by chance.

Much appreciated. :-)

On Thu, Mar 09, 2023 at 11:12:10AM +0000, David Woodhouse wrote:
> > Right, I think we're ok with the following basic rules:
> >
> > - pure arch/x86/ code should use the x86_platform function pointers to
> >   query hypervisor capabilities/peculiarities
> >
> > - cc_platform_has() should be used in generic/driver code as it
> >   abstracts away the underlying platform better. IOW, querying
> >   x86_platform.... in generic, platform-agnostic driver code looks weird to
> >   say the least
> >
> > The hope is that those two should be enough to support most guest types
> > and not let the zoo get too much out of hand...
> >
> > Thx.
>
> In
> https://lore.kernel.org/all/20230308171328.1562857-13-usama.arif@bytedance.com/
> I added an sev_es_active() helper for x86 code.
>
> Is that consistent with the vision here, or should I do something different?

So looking at sev_es_init_vc_handling() where we set that key, I'm
*thinking* that key can be removed now and the code should check

  cc_platform_has(CC_ATTR_GUEST_STATE_ENCRYPT)

instead.

Because if some of the checks in that function below fail, the guest
will terminate anyway.

Jörg, Tom?

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette