linux-kernel - [PATCH v1 0/4] x86/tdx: Allow MMIO instructions from userspace

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Message-ID: <cover.1722356794.git.legion@kernel.org>
Date: Tue, 30 Jul 2024 19:35:55 +0200
From: "Alexey Gladkov (Intel)" <legion@...nel.org>
To: linux-kernel@...r.kernel.org,
	linux-coco@...ts.linux.dev
Cc: Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	Borislav Petkov <bp@...en8.de>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Yuan Yao <yuan.yao@...el.com>,
	Geert Uytterhoeven <geert@...ux-m68k.org>,
	Yuntao Wang <ytcoode@...il.com>,
	Kai Huang <kai.huang@...el.com>,
	Baoquan He <bhe@...hat.com>,
	Oleg Nesterov <oleg@...hat.com>,
	cho@...rosoft.com,
	decui@...rosoft.com,
	John.Starks@...rosoft.com
Subject: [PATCH v1 0/4] x86/tdx: Allow MMIO instructions from userspace

Currently, MMIO inside the TDX guest is allowed from kernel space and access
from userspace is denied. This becomes a problem when working with virtual
devices in userspace.

In TDX guest MMIO instructions are emulated in #VE. The kernel code uses special
helpers to access MMIO memory to limit the number of instructions which are
used.

This patchset makes MMIO accessible from userspace. To do this additional checks
were added to ensure that the emulated instruction will not be compromised.


Alexey Gladkov (Intel) (4):
  x86/tdx: Split MMIO read and write operations
  x86/tdx: Add validation of userspace MMIO instructions
  x86/tdx: Allow MMIO from userspace
  x86/tdx: Implement movs for MMIO

 arch/x86/coco/sev/core.c  | 133 ++---------------
 arch/x86/coco/tdx/tdx.c   | 295 +++++++++++++++++++++++++++++++-------
 arch/x86/include/asm/io.h |   3 +
 arch/x86/lib/iomem.c      | 132 +++++++++++++++++
 4 files changed, 390 insertions(+), 173 deletions(-)

-- 
2.45.2