From: Hyunwoo Kim <imv4bel@gmail•com>
To: tabba@google•com, maz@kernel•org, oupton@kernel•org,
joey.gouly@arm•com, seiden@linux•ibm.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,
imv4bel@gmail•com
Subject: [PATCH v2 1/2] KVM: arm64: Clear __hyp_running_vcpu when flushing the pKVM hyp vCPU
Date: Fri, 5 Jun 2026 00:12:02 +0900 [thread overview]
Message-ID: <20260604151210.1304051-2-imv4bel@gmail.com> (raw)
In-Reply-To: <20260604151210.1304051-1-imv4bel@gmail.com>
flush_hyp_vcpu() copies the host vCPU context into the hyp's private
vCPU on every run. ctxt_to_vcpu() expects a guest context to have a
NULL __hyp_running_vcpu, which is only ever set on the host context, so
that it resolves the vCPU via container_of(). While this is generally
the case, flush_hyp_vcpu() copies the context verbatim and does not
enforce this, so a value provided by the host is dereferenced at EL2
(host -> EL2).
Fix by clearing __hyp_running_vcpu after the copy.
Fixes: be66e67f1750 ("KVM: arm64: Use the pKVM hyp vCPU structure in handle___kvm_vcpu_run()")
Signed-off-by: Hyunwoo Kim <imv4bel@gmail•com>
---
arch/arm64/kvm/hyp/nvhe/hyp-main.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
index 06db299c37a89..02c5d6e5abcbf 100644
--- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c
+++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
@@ -128,6 +128,9 @@ static void flush_hyp_vcpu(struct pkvm_hyp_vcpu *hyp_vcpu)
hyp_vcpu->vcpu.arch.ctxt = host_vcpu->arch.ctxt;
+ /* __hyp_running_vcpu must be NULL in a guest context. */
+ hyp_vcpu->vcpu.arch.ctxt.__hyp_running_vcpu = NULL;
+
hyp_vcpu->vcpu.arch.mdcr_el2 = host_vcpu->arch.mdcr_el2;
hyp_vcpu->vcpu.arch.hcr_el2 &= ~(HCR_TWI | HCR_TWE);
hyp_vcpu->vcpu.arch.hcr_el2 |= READ_ONCE(host_vcpu->arch.hcr_el2) &
--
2.43.0
next prev parent reply other threads:[~2026-06-04 15:13 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-04 15:12 [PATCH v2 0/2] KVM: arm64: Sanitise host vCPU fields copied in flush_hyp_vcpu() Hyunwoo Kim
2026-06-04 15:12 ` Hyunwoo Kim [this message]
2026-06-04 15:12 ` [PATCH v2 2/2] KVM: arm64: Bound used_lrs when flushing the pKVM hyp vCPU Hyunwoo Kim
2026-06-05 8:58 ` Marc Zyngier
2026-06-04 15:29 ` [PATCH v2 0/2] KVM: arm64: Sanitise host vCPU fields copied in flush_hyp_vcpu() Fuad Tabba
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