linux-kernel - Re: [PATCH 19/26] x86/tdx: Make pages shared in ioremap()

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Message-ID: <20211223205604.g44kez5d7iedatfo@box.shutemov.name>
Date:   Thu, 23 Dec 2021 23:56:04 +0300
From:   "Kirill A. Shutemov" <kirill@...temov.name>
To:     Borislav Petkov <bp@...en8.de>
Cc:     Dave Hansen <dave.hansen@...el.com>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Tom Lendacky <thomas.lendacky@....com>, tglx@...utronix.de,
        mingo@...hat.com, luto@...nel.org, peterz@...radead.org,
        sathyanarayanan.kuppuswamy@...ux.intel.com, aarcange@...hat.com,
        ak@...ux.intel.com, dan.j.williams@...el.com, david@...hat.com,
        hpa@...or.com, jgross@...e.com, jmattson@...gle.com,
        joro@...tes.org, jpoimboe@...hat.com, knsathya@...nel.org,
        pbonzini@...hat.com, sdeep@...are.com, seanjc@...gle.com,
        tony.luck@...el.com, vkuznets@...hat.com, wanpengli@...cent.com,
        x86@...nel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 19/26] x86/tdx: Make pages shared in ioremap()

On Thu, Dec 23, 2021 at 08:53:27PM +0100, Borislav Petkov wrote:
> On Thu, Dec 23, 2021 at 11:45:19AM -0800, Dave Hansen wrote:
> > CC_ATTR_SME_SOMETHING would get set when sme_me_mask is initialized to
> > something non-zero.  That will keep folks from falling into the same
> > trap that you did in the long term.
> 
> I guess CC_ATTR_MEM_ENCRYPT which basically says generic memory
> encryption...

Except CC_ATTR_MEM_ENCRYPT is true for TDX too, so it will also depend on
check order. It is fragile.

Frankly, naked sme_me_mask check would be better. Hm?

-- 
 Kirill A. Shutemov