linux-kernel - Re: [PATCH v4 2/6] x86/tdx: Add validation of userspace MMIO instructions

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Message-ID: <hyszoppvgphu5ogk6imqjvgwz4et7wlptanxizx4djayuugacy@2o32v5iih235>
Date: Thu, 22 Aug 2024 10:16:58 +0300
From: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
To: Alexey Gladkov <legion@...nel.org>
Cc: linux-kernel@...r.kernel.org, linux-coco@...ts.linux.dev, 
	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>, 
	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: Re: [PATCH v4 2/6] x86/tdx: Add validation of userspace MMIO
 instructions

On Wed, Aug 21, 2024 at 04:24:34PM +0200, Alexey Gladkov wrote:
> From: "Alexey Gladkov (Intel)" <legion@...nel.org>
> 
> Instructions from kernel space are considered trusted. If the MMIO
> instruction is from userspace it must be checked.
> 
> For userspace instructions, it is need to check that the INSN has not
> changed at the time of #VE and before the execution of the instruction.
> 
> Once the userspace instruction parsed is enforced that the address
> points to mapped memory of current process and that address does not
> point to private memory.
> 
> After parsing the userspace instruction, it is necessary to ensure that:
> 
> 1. the operation direction (read/write) corresponds to #VE info;
> 2. the address still points to mapped memory of current process;
> 3. the address does not point to private memory.
> 
> Signed-off-by: Alexey Gladkov (Intel) <legion@...nel.org>

Reviewed-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>

-- 
  Kiryl Shutsemau / Kirill A. Shutemov