KVM: arm64: Bound used_lrs when flushing the pKVM hyp vCPU

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flush_hyp_vcpu() copies the host vGIC state into the hyp's private vCPU
on every run. The vGIC list register save and restore use used_lrs as
their loop bound and expect it to stay within the number of implemented
list registers. While this is generally the case, flush_hyp_vcpu()
copies vgic_v3 verbatim and does not enforce this, so a value provided
by the host is used at EL2 to index vgic_lr[] and access ICH_LR<n>_EL2
(host -> EL2).

Fix by clamping used_lrs to the number of implemented list registers
after the copy, as the trusted path already does in
vgic_flush_lr_state(). The number of implemented list registers is
constant after init, so it is replicated once from
kvm_vgic_global_state.nr_lr into hyp_gicv3_nr_lr rather than read on
every entry.

Cc: stable@vger.kernel.org
Fixes: be66e67f17 ("KVM: arm64: Use the pKVM hyp vCPU structure in handle___kvm_vcpu_run()")
Signed-off-by: Hyunwoo Kim <imv4bel@gmail.com>
Reviewed-by: Fuad Tabba <tabba@google.com>
Tested-by: Fuad Tabba <tabba@google.com>
Link: https://patch.msgid.link/20260606175614.83273-3-imv4bel@gmail.com
Signed-off-by: Marc Zyngier <maz@kernel.org>

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Hyunwoo Kim 2026-06-07 02:56:11 +09:00 • committed by Marc Zyngier

parent e8042f6e1d

commit 8cc8bbbfab

3 changed files with 12 additions and 0 deletions

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1

arch/arm64/include/asm/kvm_hyp.h

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2

arch/arm64/kvm/arm.c

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9

arch/arm64/kvm/hyp/nvhe/hyp-main.c

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