Re: [PATCH v6 03/39] KVM: arm64: Return early from kvm_finalize_sys_regs() if guest has run
From: Jonathan Cameron <jonathan.cameron@huawei.com>
Date: 2026-03-19 10:12:49
Also in:
kvm, kvmarm
On Tue, 17 Mar 2026 11:40:44 +0000 Sascha Bischoff [off-list ref] wrote:
If the guest has already run, we have no business finalizing the system register state - it is too late. Therefore, check early and bail if the VM has already run.
Given it isn't in the scope below, might be worth calling out that this is skipping kvm_init_nv_sysregs() So on non NV setups isn't changing anything but on those it's indeed skipping setup of system registers. Seems correct to me, but is this a fix? So should it have a fixes tag?
quoted hunk ↗ jump to hunk
Signed-off-by: Sascha Bischoff <redacted> --- arch/arm64/kvm/sys_regs.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c index 0acd10e50aaba..42c84b7900ff5 100644 --- a/arch/arm64/kvm/sys_regs.c +++ b/arch/arm64/kvm/sys_regs.c@@ -5659,11 +5659,14 @@ int kvm_finalize_sys_regs(struct kvm_vcpu *vcpu) guard(mutex)(&kvm->arch.config_lock); + if (kvm_vm_has_ran_once(kvm)) + return 0; + /* * This hacks into the ID registers, so only perform it when the * first vcpu runs, or the kvm_set_vm_id_reg() helper will scream. */ - if (!irqchip_in_kernel(kvm) && !kvm_vm_has_ran_once(kvm)) { + if (!irqchip_in_kernel(kvm)) { u64 val; val = kvm_read_vm_id_reg(kvm, SYS_ID_AA64PFR0_EL1) & ~ID_AA64PFR0_EL1_GIC;