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([58.123.110.97]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2c164f6d69csm129196425ad.2.2026.06.06.10.57.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 06 Jun 2026 10:57:19 -0700 (PDT) From: Hyunwoo Kim 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, stable@vger.kernel.org, imv4bel@gmail.com Subject: [PATCH v3 2/2] KVM: arm64: Bound used_lrs when flushing the pKVM hyp vCPU Date: Sun, 7 Jun 2026 02:56:11 +0900 Message-ID: <20260606175614.83273-3-imv4bel@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260606175614.83273-1-imv4bel@gmail.com> References: <20260606175614.83273-1-imv4bel@gmail.com> Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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 --- 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 8d06b62e7188..e9b2b0c40ec6 100644 --- a/arch/arm64/include/asm/kvm_hyp.h +++ b/arch/arm64/include/asm/kvm_hyp.h @@ -157,5 +157,6 @@ 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 long kvm_nvhe_sym(hyp_nr_cpus); +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 9453321ef8c6..9ffd5d4079e6 100644 --- a/arch/arm64/kvm/arm.c +++ b/arch/arm64/kvm/arm.c @@ -2426,6 +2426,8 @@ 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 02c5d6e5abcb..a0da08caa6c2 100644 --- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c +++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c @@ -24,6 +24,9 @@ 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 __hyp_sve_save_guest(struct kvm_vcpu *vcpu) @@ -142,6 +145,12 @@ static void flush_hyp_vcpu(struct pkvm_hyp_vcpu *hyp_vcpu) 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); + hyp_vcpu->vcpu.arch.pid = host_vcpu->arch.pid; } -- 2.43.0