Date:   Fri, 24 Dec 2021 14:03:00 +0300
From:   "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
To:     Borislav Petkov <bp@alien8.de>
Cc:     "Kirill A. Shutemov" <kirill@shutemov.name>,
        Dave Hansen <dave.hansen@intel.com>,
        Tom Lendacky <thomas.lendacky@amd.com>, tglx@linutronix.de,
        mingo@redhat.com, luto@kernel.org, peterz@infradead.org,
        sathyanarayanan.kuppuswamy@linux.intel.com, aarcange@redhat.com,
        ak@linux.intel.com, dan.j.williams@intel.com, david@redhat.com,
        hpa@zytor.com, jgross@suse.com, jmattson@google.com,
        joro@8bytes.org, jpoimboe@redhat.com, knsathya@kernel.org,
        pbonzini@redhat.com, sdeep@vmware.com, seanjc@google.com,
        tony.luck@intel.com, vkuznets@redhat.com, wanpengli@tencent.com,
        x86@kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 19/26] x86/tdx: Make pages shared in ioremap()
Message-ID: <20211224110300.7zj3nc5nbbv7jobp@black.fi.intel.com>
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On Thu, Dec 23, 2021 at 10:09:26PM +0100, Borislav Petkov wrote:
> On Thu, Dec 23, 2021 at 11:56:04PM +0300, Kirill A. Shutemov wrote:
> > Except CC_ATTR_MEM_ENCRYPT is true for TDX too, so it will also depend on
> > check order. It is fragile.
> 
> So the query you wanna do is:
> 
> 	if (memory encryption in use)
> 		use mask;
> 
> and the mask you use depends on whether it is SEV or TDX. Right?
> 
> If so, you can either do a cc_get_mask() function which gives you either
> the SEV or TDX mask or simply do:
> 
> 	if (CC_ATTR_MEM_ENCRYPT) {
> 		if (CC_ATTR_GUEST_TDX)
> 			mask = tdx_shared_mask();
> 		else if (sme_me_mask)
> 			mask = sme_me_mask;
> 	}
> 
> Yeah, sme_me_mask has become synonymous with the kernel running as a AMD
> confidential guest. I need to think about how to make this cleaner...

Okay. Meanwhile I leave it this way:

	pgprot_t pgprot_cc_encrypted(pgprot_t prot)
	{
		if (cc_platform_has(CC_ATTR_MEM_ENCRYPT)) {
			if (cc_platform_has(CC_ATTR_GUEST_TDX))
				return __pgprot(pgprot_val(prot) & ~tdx_shared_mask());
			else if (sme_me_mask)
				return __pgprot(__sme_set(pgprot_val(prot)));
			else
				WARN_ON_ONCE(1);
		}

		return prot;
	}
	EXPORT_SYMBOL_GPL(pgprot_cc_encrypted);

	pgprot_t pgprot_cc_decrypted(pgprot_t prot)
	{
		if (cc_platform_has(CC_ATTR_MEM_ENCRYPT)) {
			if (cc_platform_has(CC_ATTR_GUEST_TDX))
				return __pgprot(pgprot_val(prot) | tdx_shared_mask());
			else if (sme_me_mask)
				return __pgprot(__sme_clr(pgprot_val(prot)));
			else
				WARN_ON_ONCE(1);
		}

		return prot;
	}
	EXPORT_SYMBOL_GPL(pgprot_cc_decrypted);

-- 
 Kirill A. Shutemov