linux-kernel - Re: [PATCH V4 4/4] x86/tdx: Remove TDX specific idle routine

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Message-ID: <avodert2s5di3s4m3ays6z4qhskwfz6zxenoq3rsf7crpclkfz@jaq7ptkmco4o>
Date: Wed, 12 Feb 2025 15:03:30 +0200
From: "Kirill A. Shutemov" <kirill@...temov.name>
To: Vishal Annapurve <vannapurve@...gle.com>
Cc: x86@...nel.org, linux-kernel@...r.kernel.org, pbonzini@...hat.com, 
	seanjc@...gle.com, erdemaktas@...gle.com, ackerleytng@...gle.com, jxgao@...gle.com, 
	sagis@...gle.com, oupton@...gle.com, pgonda@...gle.com, 
	dave.hansen@...ux.intel.com, linux-coco@...ts.linux.dev, chao.p.peng@...ux.intel.com, 
	isaku.yamahata@...il.com, sathyanarayanan.kuppuswamy@...ux.intel.com
Subject: Re: [PATCH V4 4/4] x86/tdx: Remove TDX specific idle routine

On Wed, Feb 12, 2025 at 12:07:47AM +0000, Vishal Annapurve wrote:
> With explicit dependency on CONFIG_PARAVIRT and TDX specific
> halt()/safe_halt() routines in place, default_idle() is safe to execute for
> TDX VMs. Remove TDX specific idle routine override which is now
> redundant.

I am not convinced that it is good idea.

It adds two needless flipping of IF in the hot path: first enabling
interrupts in tdx_safe_halt() and disabling it back in default_idle().

-- 
  Kiryl Shutsemau / Kirill A. Shutemov