Subject: Re: [PATCH 19/26] x86/tdx: Make pages shared in ioremap()
To:     "Kirill A. Shutemov" <kirill@shutemov.name>,
        Borislav Petkov <bp@alien8.de>
Cc:     "Kirill A. Shutemov" <kirill.shutemov@linux.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
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From:   Dave Hansen <dave.hansen@intel.com>
Message-ID: <b4b54116-1cd7-468a-0889-d497268cbfb2@intel.com>
Date:   Mon, 3 Jan 2022 08:50:12 -0800
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On 1/3/22 7:15 AM, Kirill A. Shutemov wrote:
> On Mon, Jan 03, 2022 at 03:29:44PM +0100, Borislav Petkov wrote:
>> On Mon, Jan 03, 2022 at 05:17:05PM +0300, Kirill A. Shutemov wrote:
>>> I'm not sure how to unwind this dependency hell. Any clues?
>> Forward-declaration maybe?
>>
>> I.e., something like
>>
>> struct task_struct;
>>
>> at the top of arch/x86/include/asm/switch_to.h, for example...
> Forward-declaration only works if you refer the struct/union by pointer,
> not value.
> 
> And pgprot_t is not always a struct and when it is a struct it is
> anonymous.
> 
> See "git grep 'typedef.*pgprot_t;'".

In the end, the new functions get used like this:

	prot = pgprot_decrypted(prot);

I think they _could_ be:

	pgprot_set_decrypted(&prot);

Which would let you have a declaration like this:

	extern void pgprot_cc_set_decrypted(pgprot_t *prot);

It does not exactly give me warm and fuzzy feelings, but it would work
around the header problem.