linux-kernel - Re: [PATCHv2 22/29] x86/tdx: Make pages shared in ioremap()

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Date:   Tue, 15 Feb 2022 11:50:34 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Cc:     Dave Hansen <dave.hansen@...el.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: [PATCHv2 22/29] x86/tdx: Make pages shared in ioremap()

On Tue, Feb 15, 2022 at 01:09:26AM +0300, Kirill A. Shutemov wrote:
> pgprotval_t cc_enc(pgprotval_t protval)
> {
> 	if (sme_me_mask)
> 		return __sme_set(protval);
> 	else if (cpu_feature_enabled(X86_FEATURE_TDX_GUEST))
> 		return protval & ~tdx_shared_mask();
				 ^^^^^^^^^^^^^^^^^^^

LGTM.

Btw, what about sticking the mask tdx_shared_mask() returns into a
proper u64 variable and using it everywhere, just like sme_me_mask?

We could unify it later into a common encryption mask, see thread
starting here:

https://lore.kernel.org/r/YgZ427v95xcdOKSC@zn.tnic

-- 
Regards/Gruss,
    Boris.

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