linux-kernel - Re: [PATCH 5/6] x86_64,hyperv: Use direct call to hypercall-page

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Message-ID: <20250429151903.GK4198@noisy.programming.kicks-ass.net>
Date: Tue, 29 Apr 2025 17:19:03 +0200
From: Peter Zijlstra <peterz@...radead.org>
To: Michael Kelley <mhklinux@...look.com>
Cc: "x86@...nel.org" <x86@...nel.org>,
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Subject: Re: [PATCH 5/6] x86_64,hyperv: Use direct call to hypercall-page

On Sun, Apr 27, 2025 at 03:58:54AM +0000, Michael Kelley wrote:

> Indeed, control never returns from static_call_update(). Prior to
> hyperv_cleanup() running, crash_smp_send_stop() has been called to
> stop all the other CPUs, and it does not update cpu_online_mask to
> reflect the other CPUs being stopped.
> 
> static_call_update() runs this call sequence:
> 
> arch_static_call_transform()
> __static_call_transform()
> smp_text_poke_single()
> smp_text_poke_batch_finish()
> smp_text_poke_sync_each_cpu()
> 
> smp_text_poke_sync_each_cpu() sends an IPI to each CPU in
> cpu_online_mask, and of course the other CPUs never respond, so
> it waits forever.

Fair enough. I'll just remove this final call. Thanks!