[PATCH 1/5] KVM: arm64: Force ID_AA64PFR0_EL1.GIC=1 when exposing a virtual GICv3
From: Marc Zyngier <maz@kernel.org>
Date: 2021-09-24 08:28:53
Also in:
kvm, kvmarm
Subsystem:
arm64 port (aarch64 architecture), kernel virtual machine for arm64 (kvm/arm64), the rest · Maintainers:
Catalin Marinas, Will Deacon, Marc Zyngier, Oliver Upton, Linus Torvalds
Until now, we always let ID_AA64PFR0_EL1.GIC reflect the value visible on the host, even if we were running a GICv2-enabled VM on a GICv3+compat host. That's fine, but we also now have the case of a host that does not expose ID_AA64PFR0_EL1.GIC==1 despite having a vGIC. Yes, this is confusing. Thank you M1. Let's go back to first principles and expose ID_AA64PFR0_EL1.GIC=1 when a GICv3 is exposed to the guest. This also hides a GICv4.1 CPU interface from the guest which has no business knowing about the v4.1 extension. Signed-off-by: Marc Zyngier <maz@kernel.org> --- arch/arm64/kvm/sys_regs.c | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 1d46e185f31e..0e8fc29df19c 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c@@ -1075,6 +1075,11 @@ static u64 read_id_reg(const struct kvm_vcpu *vcpu, val |= FIELD_PREP(ARM64_FEATURE_MASK(ID_AA64PFR0_CSV2), (u64)vcpu->kvm->arch.pfr0_csv2); val &= ~ARM64_FEATURE_MASK(ID_AA64PFR0_CSV3); val |= FIELD_PREP(ARM64_FEATURE_MASK(ID_AA64PFR0_CSV3), (u64)vcpu->kvm->arch.pfr0_csv3); + if (irqchip_in_kernel(vcpu->kvm) && + vcpu->kvm->arch.vgic.vgic_model == KVM_DEV_TYPE_ARM_VGIC_V3) { + val &= ~ARM64_FEATURE_MASK(ID_AA64PFR0_GIC); + val |= FIELD_PREP(ARM64_FEATURE_MASK(ID_AA64PFR0_GIC), 1); + } break; case SYS_ID_AA64PFR1_EL1: val &= ~ARM64_FEATURE_MASK(ID_AA64PFR1_MTE);
--
2.30.2
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