linux-kernel - Re: [patch V6 07/31] rseq, virt: Retrigger RSEQ after vcpu

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Message-ID: <365bf960-9850-4e34-8a97-c048f199b151@efficios.com>
Date: Tue, 28 Oct 2025 11:08:25 -0400
From: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
To: Thomas Gleixner <tglx@...utronix.de>, LKML <linux-kernel@...r.kernel.org>
Cc: Michael Jeanson <mjeanson@...icios.com>, Jens Axboe <axboe@...nel.dk>,
 Peter Zijlstra <peterz@...radead.org>, "Paul E. McKenney"
 <paulmck@...nel.org>, x86@...nel.org, Sean Christopherson
 <seanjc@...gle.com>, Wei Liu <wei.liu@...nel.org>
Subject: Re: [patch V6 07/31] rseq, virt: Retrigger RSEQ after vcpu_run()

On 2025-10-27 04:44, Thomas Gleixner wrote:
> Hypervisors invoke resume_user_mode_work() before entering the guest, which
> clears TIF_NOTIFY_RESUME. The @regs argument is NULL as there is no user
> space context available to them, so the rseq notify handler skips
> inspecting the critical section, but updates the CPU/MM CID values
> unconditionally so that the eventual pending rseq event is not lost on the
> way to user space.
[...]

Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>

-- 
Mathieu Desnoyers
EfficiOS Inc.
https://www.efficios.com