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KVM: arm64: Return early from kvm_finalize_sys_regs() if guest has run

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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.

This change also stops kvm_init_nv_sysregs() from being called once
the RM has run once. Although this looks like a behavioural change,
the function returns early once it has been called the first time.

Signed-off-by: Sascha Bischoff <sascha.bischoff@arm.com>
Link: https://patch.msgid.link/20260319154937.3619520-4-sascha.bischoff@arm.com
Signed-off-by: Marc Zyngier <maz@kernel.org>
This commit is contained in:
Sascha Bischoff 2026-03-19 15:50:28 +00:00 committed by Marc Zyngier
parent 3a2857da94
commit cbd8c958be
1 changed files with 4 additions and 1 deletions
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5
arch/arm64/kvm/sys_regs.c
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@ -5659,11 +5659,14 @@ int kvm_finalize_sys_regs(struct kvm_vcpu *vcpu)
guard(mutex)(&kvm->arch.config_lock); 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 * 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. * 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; u64 val;
val = kvm_read_vm_id_reg(kvm, SYS_ID_AA64PFR0_EL1) & ~ID_AA64PFR0_EL1_GIC; val = kvm_read_vm_id_reg(kvm, SYS_ID_AA64PFR0_EL1) & ~ID_AA64PFR0_EL1_GIC;