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Date:   Tue, 22 Feb 2022 16:52:53 +0300
From:   "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
To:     Borislav Petkov <bp@alien8.de>
Cc:     Dave Hansen <dave.hansen@intel.com>, tglx@linutronix.de,
        mingo@redhat.com, luto@kernel.org, peterz@infradead.org,
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        x86@kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCHv3 02/32] x86/coco: Add API to handle encryption mask
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On Tue, Feb 22, 2022 at 02:37:27PM +0100, Borislav Petkov wrote:
> On Tue, Feb 22, 2022 at 02:03:12PM +0300, Kirill A. Shutemov wrote:
> > I would rather make cc_mkenc()/cc_mkdec() to operate on u64 (or
> > phys_addr_t?) while pgprot_encrypted()/pgprot_decrypted() cover pgprot_t.
> > It also makes set_memory cleaner:
> > 
> > 	cpa.mask_set = __pgprot(enc ? cc_mkenc(0) : cc_mkdec(0));
> > 	cpa.mask_clr = __pgprot(enc ? cc_mkdec(0) : cc_mkenc(0));
> > 
> > Opinions?
> 
> Right, do I see it correctly that the cc_mk{enc,dec}() things should
> take a u64 as an argument and return a pgprot_t, and that would be the
> most optimal way for all the use cases?

No, not really. With u64-in-u64-out in tdx_enc_status_changed() we have 

	if (!enc) {
		start |= cc_mkdec(0);
		end |= cc_mkdec(0);
	}

to iterate over the range of physical addresses with shared bit set.
With u64-in-pgprot_t-out we will have do add pgprot_val() there.

We will have more cases like this in attestation code when we need to do
hypercall on a shared page.

-- 
 Kirill A. Shutemov