From mboxrd@z Thu Jan  1 00:00:00 1970
From: Peter Zijlstra <peterz@infradead.org>
Date: Fri, 14 Jun 2019 11:44:08 +0000
Subject: Re: [PATCH, RFC 44/62] x86/mm: Set KeyIDs in encrypted VMAs for MKTME
Message-Id: <20190614114408.GD3436@hirez.programming.kicks-ass.net>
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References: <20190508144422.13171-1-kirill.shutemov@linux.intel.com>
 <20190508144422.13171-45-kirill.shutemov@linux.intel.com>
In-Reply-To: <20190508144422.13171-45-kirill.shutemov@linux.intel.com>
To: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>, x86@kernel.org, Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>, Borislav Petkov <bp@alien8.de>, Andy Lutomirski <luto@amacapital.net>, David Howells <dhowells@redhat.com>, Kees Cook <keescook@chromium.org>, Dave Hansen <dave.hansen@intel.com>, Kai Huang <kai.huang@linux.intel.com>, Jacob Pan <jacob.jun.pan@linux.intel.com>, Alison Schofield <alison.schofield@intel.com>, linux-mm@kvack.org, kvm@vger.kernel.org, keyrings@vger.kernel.org, linux-kernel@vger.kernel.org

On Wed, May 08, 2019 at 05:44:04PM +0300, Kirill A. Shutemov wrote:
> From: Alison Schofield <alison.schofield@intel.com>
> 
> MKTME architecture requires the KeyID to be placed in PTE bits 51:46.
> To create an encrypted VMA, place the KeyID in the upper bits of
> vm_page_prot that matches the position of those PTE bits.
> 
> When the VMA is assigned a KeyID it is always considered a KeyID
> change. The VMA is either going from not encrypted to encrypted,
> or from encrypted with any KeyID to encrypted with any other KeyID.
> To make the change safely, remove the user pages held by the VMA
> and unlink the VMA's anonymous chain.

This does not look like a transformation that preserves content; is
mprotect() still a suitable name?