linux-kernel - Re: [PATCH v4 2/2] x86/devmem: Drop /dev/mem access for confidential guests

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Message-ID: <74d7d392-82ce-46b1-81ad-a5f1c1bdf62c@intel.com>
Date: Mon, 28 Apr 2025 09:36:42 -0700
From: Dave Hansen <dave.hansen@...el.com>
To: Jianxiong Gao <jxgao@...gle.com>
Cc: Dan Williams <dan.j.williams@...el.com>, dave.hansen@...ux.intel.com,
 x86@...nel.org, Kees Cook <kees@...nel.org>, Ingo Molnar <mingo@...nel.org>,
 Naveen N Rao <naveen@...nel.org>, Vishal Annapurve <vannapurve@...gle.com>,
 Kirill Shutemov <kirill.shutemov@...ux.intel.com>,
 Nikolay Borisov <nik.borisov@...e.com>, stable@...r.kernel.org,
 linux-coco@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 2/2] x86/devmem: Drop /dev/mem access for confidential
 guests

On 4/28/25 09:30, Jianxiong Gao wrote:
> On Mon, Apr 28, 2025 at 8:53 AM Dave Hansen <dave.hansen@...el.com> wrote:
>> Would most developers reading this know what an "SEPT violation" is or
>> what its implications are?
>>
>> This results in an immediate exit from and termination of the TDX guest,
>> right?
>>
> In most cases yes but it depends on the settings.

There's also disable_sept_ve() in the kernel.

So perhaps I should have said:

	This <normally*> results in an immediate exit from and
	termination of the TDX guest right?

	 * Ignoring debug and other non-production silliness