[PATCH 06/12] KVM: arm64: Zero ID_AA64PFR0_EL1.GIC when no GICv3 is presented to the guest

Marc Zyngier
2024-08-20T10:06:14Z

In order to be consistent, we shouldn't advertise a GICv3 when none
is actually usable by the guest.

Wipe the feature when these conditions apply, and allow the field
to be written from userspace.

Signed-off-by: Marc Zyngier <maz@kernel.org>
---
arch/arm64/kvm/sys_regs.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index bc2d54da3827..7d00d7e359e1 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -2365,7 +2365,6 @@ static const struct sys_reg_desc sys_reg_descs[] = {
ID_AA64PFR0_EL1_MPAM |
ID_AA64PFR0_EL1_SVE |
ID_AA64PFR0_EL1_RAS |
- ID_AA64PFR0_EL1_GIC |
ID_AA64PFR0_EL1_AdvSIMD |
ID_AA64PFR0_EL1_FP), },
ID_SANITISED(ID_AA64PFR1_EL1),
@@ -4634,6 +4633,11 @@ int kvm_finalize_sys_regs(struct kvm_vcpu *vcpu)

guard(mutex)(&kvm->arch.config_lock);

+ if (!kvm_has_gicv3(kvm)) {
+ kvm->arch.id_regs[IDREG_IDX(SYS_ID_AA64PFR0_EL1)] &= ~ID_AA64PFR0_EL1_GIC_MASK;
+ kvm->arch.id_regs[IDREG_IDX(SYS_ID_PFR1_EL1)] &= ~ID_PFR1_EL1_GIC_MASK;
+ }
+
if (vcpu_has_nv(vcpu)) {
int ret = kvm_init_nv_sysregs(kvm);
if (ret)
--
2.39.2