From 2c5e72b9fbf83fdfa724e9f1af0f418ccf8739b8 Mon Sep 17 00:00:00 2001 From: Hyunwoo Kim Date: Thu, 16 Jul 2026 14:50:36 +0100 Subject: [PATCH] KVM: arm64: Bound used_lrs when flushing the pKVM hyp vCPU commit 8cc8bbbfab14c22c5551d0dd19b208a44b141c76 upstream. 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_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: be66e67f1750 ("KVM: arm64: Use the pKVM hyp vCPU structure in handle___kvm_vcpu_run()") Signed-off-by: Hyunwoo Kim Reviewed-by: Fuad Tabba Tested-by: Fuad Tabba Link: https://patch.msgid.link/20260606175614.83273-3-imv4bel@gmail.com Signed-off-by: Marc Zyngier [ tabba: adjust context in flush_hyp_vcpu() and kvm_hyp.h ] Signed-off-by: Fuad Tabba Signed-off-by: Sasha Levin --- arch/arm64/include/asm/kvm_hyp.h | 1 + arch/arm64/kvm/arm.c | 2 ++ arch/arm64/kvm/hyp/nvhe/hyp-main.c | 9 +++++++++ 3 files changed, 12 insertions(+) diff --git a/arch/arm64/include/asm/kvm_hyp.h b/arch/arm64/include/asm/kvm_hyp.h index 51cd106cd840..1b209efac972 100644 --- a/arch/arm64/include/asm/kvm_hyp.h +++ b/arch/arm64/include/asm/kvm_hyp.h @@ -146,5 +146,6 @@ extern u64 kvm_nvhe_sym(id_aa64smfr0_el1_sys_val); extern unsigned long kvm_nvhe_sym(__icache_flags); extern unsigned int kvm_nvhe_sym(kvm_arm_vmid_bits); extern unsigned int kvm_nvhe_sym(kvm_host_sve_max_vl); +extern unsigned int kvm_nvhe_sym(hyp_gicv3_nr_lr); #endif /* __ARM64_KVM_HYP_H__ */ diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c index 3ae529e967c7..e49ead6d005c 100644 --- a/arch/arm64/kvm/arm.c +++ b/arch/arm64/kvm/arm.c @@ -2026,6 +2026,8 @@ static int __init init_subsystems(void) switch (err) { case 0: vgic_present = true; + if (static_branch_unlikely(&kvm_vgic_global_state.gicv3_cpuif)) + kvm_nvhe_sym(hyp_gicv3_nr_lr) = kvm_vgic_global_state.nr_lr; break; case -ENODEV: case -ENXIO: diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/hyp-main.c index 350d1775a5ce..aa6c486667e7 100644 --- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c +++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c @@ -22,6 +22,9 @@ DEFINE_PER_CPU(struct kvm_nvhe_init_params, kvm_init_params); +/* Number of implemented GICv3 LRs. Used by flush_hyp_vcpu(). */ +unsigned int hyp_gicv3_nr_lr; + void __kvm_hyp_host_forward_smc(struct kvm_cpu_context *host_ctxt); static void flush_hyp_vcpu(struct pkvm_hyp_vcpu *hyp_vcpu) @@ -46,6 +49,12 @@ static void flush_hyp_vcpu(struct pkvm_hyp_vcpu *hyp_vcpu) hyp_vcpu->vcpu.arch.vsesr_el2 = host_vcpu->arch.vsesr_el2; hyp_vcpu->vcpu.arch.vgic_cpu.vgic_v3 = host_vcpu->arch.vgic_cpu.vgic_v3; + + /* Bound used_lrs by the number of implemented list registers. */ + hyp_vcpu->vcpu.arch.vgic_cpu.vgic_v3.used_lrs = + min_t(unsigned int, + hyp_vcpu->vcpu.arch.vgic_cpu.vgic_v3.used_lrs, + hyp_gicv3_nr_lr); } static void sync_hyp_vcpu(struct pkvm_hyp_vcpu *hyp_vcpu)