linux-kernel - Re: [PATCH] x86/tdx: Generate SIGBUS on userspace MMIO

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Message-ID: <ngl63zhudmeskbcga3i3hsdtensd7bfoztnsiu7yj7pxbyzx47@tj5szegw6qrd>
Date: Thu, 23 May 2024 13:14:30 +0300
From: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
To: 
	Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>
Cc: Dave Hansen <dave.hansen@...ux.intel.com>, 
	Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>, 
	x86@...nel.org, "H. Peter Anvin" <hpa@...or.com>, linux-coco@...ts.linux.dev, 
	linux-kernel@...r.kernel.org, cho@...rosoft.com, decui@...rosoft.com, 
	John.Starks@...rosoft.com
Subject: Re: [PATCH] x86/tdx: Generate SIGBUS on userspace MMIO

On Tue, May 21, 2024 at 06:35:49AM -0700, Kuppuswamy Sathyanarayanan wrote:
> 
> On 5/21/24 12:35 AM, Kirill A. Shutemov wrote:
> > Currently attempt to do MMIO from userspace in TDX guest leads to
> > warning about unexpect #VE and SIGSEGV being delivered to the process.
> >
> > Enlightened userspace might choose to deal with MMIO on their own if
> > kernel doesn't emulate it.
> 
> Any specific use cases ? Like who is using it?

Microsoft folks wanted it. Chris, Dexuan, John, any comments?

But it is generally right thing to do. SIGBUS is right signal to deliver.

-- 
  Kiryl Shutsemau / Kirill A. Shutemov