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From:   Jan Henrik Weinstock <jan@mwa.re>
Date:   Fri, 20 Oct 2023 20:45:05 +0200
Message-ID: <CANi1PHhzk80HvwQbBM46gpJ6_AA_P6+m5Jo0Nuy_MAdA4C2BhQ@mail.gmail.com>
Subject: KVM exit to userspace on WFI
To:     maz@kernel.org, oliver.upton@linux.dev, james.morse@arm.com,
        suzuki.poulose@arm.com, yuzenghui@huawei.com,
        catalin.marinas@arm.com, will@kernel.org
Cc:     linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev,
        linux-kernel@vger.kernel.org,
        =?UTF-8?Q?Lukas_J=C3=BCnger?= <lukas@mwa.re>
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Hi all,

I am looking for a way to have KVM_RUN exit back to userspace once the
vcpu encounters a WFI. It seems the kvm_run->request_interrupt_window
flag is currently ignored by arm64. So my solution thus far is to
patch kvm_handle_wfx in arch/arm64/kvm/handle_exit.c and return to
userspace with KVM_EXIT_IRQ_WINDOW_OPEN - working example attached.
Any chance to get this (or something similar) mainline?

--=20
Dr.-Ing. Jan Henrik Weinstock
Managing Director

MachineWare GmbH | www.machineware.de
H=C3=BChnermarkt 19, 52062 Aachen, Germany
Amtsgericht Aachen HRB25734

Gesch=C3=A4ftsf=C3=BChrung
Lukas J=C3=BCnger
Dr.-Ing. Jan Henrik Weinstock

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