Commit 89896cc1 authored by Marc Zyngier's avatar Marc Zyngier Committed by Oliver Upton
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KVM: arm64: nv: Fold GICv3 host trapping requirements into guest setup 



Popular HW that is able to use NV also has a broken vgic implementation
that requires trapping.

On such HW, propagate the host trap bits into the guest's shadow
ICH_HCR_EL2 register, making sure we don't allow an L2 guest to bring
the system down.

This involves a bit of tweaking so that the emulation code correctly
poicks up the shadow state as needed, and to only partially sync
ICH_HCR_EL2 back with the guest state to capture EOIcount.

Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20250225172930.1850838-15-maz@kernel.org


Signed-off-by: default avatarOliver Upton <oliver.upton@linux.dev>
parent 7682c023

arch/arm64/kvm/vgic/vgic-v3-nested.c

+17 −3
Original line number Diff line number Diff line
@@ -296,9 +296,19 @@ static void vgic_v3_create_shadow_state(struct kvm_vcpu *vcpu, 
					struct vgic_v3_cpu_if *s_cpu_if)

{

	struct vgic_v3_cpu_if *host_if = &vcpu->arch.vgic_cpu.vgic_v3;

	u64 val = 0;

	int i;



	s_cpu_if->vgic_hcr = __vcpu_sys_reg(vcpu, ICH_HCR_EL2);

	/*

	 * If we're on a system with a broken vgic that requires

	 * trapping, propagate the trapping requirements.

	 *

	 * Ah, the smell of rotten fruits...

	 */

	if (static_branch_unlikely(&vgic_v3_cpuif_trap))

		val = host_if->vgic_hcr & (ICH_HCR_EL2_TALL0 | ICH_HCR_EL2_TALL1 |

					   ICH_HCR_EL2_TC | ICH_HCR_EL2_TDIR);

	s_cpu_if->vgic_hcr = __vcpu_sys_reg(vcpu, ICH_HCR_EL2) | val;

	s_cpu_if->vgic_vmcr = __vcpu_sys_reg(vcpu, ICH_VMCR_EL2);

	s_cpu_if->vgic_sre = host_if->vgic_sre;
@@ -335,6 +345,7 @@ void vgic_v3_put_nested(struct kvm_vcpu *vcpu) 
{

	struct shadow_if *shadow_if = get_shadow_if();

	struct vgic_v3_cpu_if *s_cpu_if = &shadow_if->cpuif;

	u64 val;

	int i;



	__vgic_v3_save_vmcr_aprs(s_cpu_if);
@@ -345,7 +356,10 @@ void vgic_v3_put_nested(struct kvm_vcpu *vcpu) 
	 * Translate the shadow state HW fields back to the virtual ones

	 * before copying the shadow struct back to the nested one.

	 */

	__vcpu_sys_reg(vcpu, ICH_HCR_EL2) = s_cpu_if->vgic_hcr;

	val = __vcpu_sys_reg(vcpu, ICH_HCR_EL2);

	val &= ~ICH_HCR_EL2_EOIcount_MASK;

	val |= (s_cpu_if->vgic_hcr & ICH_HCR_EL2_EOIcount_MASK);

	__vcpu_sys_reg(vcpu, ICH_HCR_EL2) = val;

	__vcpu_sys_reg(vcpu, ICH_VMCR_EL2) = s_cpu_if->vgic_vmcr;



	for (i = 0; i < 4; i++) {
@@ -354,7 +368,7 @@ void vgic_v3_put_nested(struct kvm_vcpu *vcpu) 
	}



	for_each_set_bit(i, &shadow_if->lr_map, kvm_vgic_global_state.nr_lr) {

		u64 val = __vcpu_sys_reg(vcpu, ICH_LRN(i));

		val = __vcpu_sys_reg(vcpu, ICH_LRN(i));



		val &= ~ICH_LR_STATE;

		val |= s_cpu_if->vgic_lr[i] & ICH_LR_STATE;