From: Fuad Tabba <fuad.tabba@linux.dev>
To: Marc Zyngier <maz@kernel.org>
Cc: Oliver Upton <oupton@kernel.org>, Joey Gouly <joey.gouly@arm.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Zenghui Yu <yuzenghui@huawei.com>,
Steffen Eiden <seiden@linux.ibm.com>,
kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org,
kvm@vger.kernel.org, Fuad Tabba <tabba@google.com>
Subject: Re: [PATCH 2/7] KVM: arm64: Move OUTSIDE_GUEST_MODE publication past context being saved
Date: Thu, 15 Oct 2026 13:57:13 +0100 [thread overview]
Message-ID: <20261015125713.2650696-1-fuad.tabba@linux.dev> (raw)
In-Reply-To: <20261015100539.1011760-3-maz@kernel.org>
Hi Marc,
On Thu, 15 Oct 2026 11:05:34 +0100, Marc Zyngier <maz@kernel.org> wrote:
[...]
> However, code that uses OUTSIDE_GUEST_MODE as a synchronisation point
> relies on the vcpu state to have been written back to the in-memory
> structures. Clearly, this is not what is happening
nit: missing full stop.
[...]
> diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
[...]
> @@ -1390,6 +1389,12 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
>
> kvm_arch_vcpu_ctxsync_fp(vcpu);
>
> + /*
> + * All the state has been synchronised, let advertise
> + * we're outside of the guest.
> + */
> + smp_store_release(&vcpu->mode, OUTSIDE_GUEST_MODE);
nit: could this say the vgic state rather than all the state? In pKVM,
a non-protected guest's context comes back later, in
handle_exit_pkvm_state() or on demand, and with VHE the EL1 sysregs
stay on the CPU until vcpu_put(). Also "let's advertise".
Cheers,
/fuad
next prev parent reply other threads:[~2026-10-15 12:57 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-15 10:05 [PATCH 0/7] KVM: arm64: Fix cross-CPU vcpu pausing Marc Zyngier
2026-10-15 10:05 ` [PATCH 1/7] KVM: arm64: nv: Move L2->L1 switch on interrupt early Marc Zyngier
2026-10-15 10:05 ` [PATCH 2/7] KVM: arm64: Move OUTSIDE_GUEST_MODE publication past context being saved Marc Zyngier
2026-10-15 12:57 ` Fuad Tabba [this message]
2026-10-15 13:52 ` Marc Zyngier
2026-10-15 13:59 ` Fuad Tabba
2026-10-15 10:05 ` [PATCH 3/7] KVM: arm64: Move IN_GUEST_MODE ahead of state being loaded Marc Zyngier
2026-10-15 10:05 ` [PATCH 4/7] KVM: arm64: Turn vcpu->arch.pause into a counter Marc Zyngier
2026-10-15 10:05 ` [PATCH 5/7] KVM: arm64: Add helpers to halt a vCPU Marc Zyngier
2026-10-15 12:57 ` Fuad Tabba
2026-10-15 13:13 ` Marc Zyngier
2026-10-15 13:15 ` Fuad Tabba
2026-10-15 10:05 ` [PATCH 6/7] KVM: arm64: vgic: Stop the target vcpu when disabling LPIs Marc Zyngier
2026-10-15 10:05 ` [PATCH 7/7] KVM: arm64: vgic-its: Stop the VM when handling MOVALL Marc Zyngier
2026-10-15 12:57 ` [PATCH 0/7] KVM: arm64: Fix cross-CPU vcpu pausing Fuad Tabba
2026-10-15 13:30 ` Marc Zyngier
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