Re: [PATCH v2 05/45] KVM: arm64: GICv3: Detect and work around the lack of ICV_DIR_EL1 trapping

[Marc Zyngier <maz@kernel.org>]

+Fuad

On Thu, 13 Nov 2025 19:06:31 +0000,
Mark Brown <broonie@kernel.org> wrote:
> 
> [1  <text/plain; us-ascii (7bit)>]
> On Thu, Nov 13, 2025 at 06:15:29PM +0000, Marc Zyngier wrote:
> > Mark Brown <broonie@kernel.org> wrote:
> 
> > > The arch_timer case bisects to this patch in -next, regular nVHE mode
> > > runs this test happily.
> 
> > My hunch is that we're missing something like the hack below, but I
> > haven't tried it yet.
> 
> > I'll probably get to it tomorrow.
> 
> That still fails FWIW.

Yup, this has uncovered yet another pKVM bug, which doesn't preserve
the vgic_model in its private kvm structure. I'm able to make it work
with this:

diff --git a/arch/arm64/kvm/hyp/nvhe/pkvm.c b/arch/arm64/kvm/hyp/nvhe/pkvm.c
index 43bde061b65de..8911338961c5b 100644
--- a/arch/arm64/kvm/hyp/nvhe/pkvm.c
+++ b/arch/arm64/kvm/hyp/nvhe/pkvm.c
@@ -337,6 +337,9 @@ static void pkvm_init_features_from_host(struct pkvm_hyp_vm *hyp_vm, const struc
 	/* CTR_EL0 is always under host control, even for protected VMs. */
 	hyp_vm->kvm.arch.ctr_el0 = host_kvm->arch.ctr_el0;
 
+	/* Preserve the vgic model so that GICv3 emulation works */
+	hyp_vm->kvm.arch.vgic.vgic_model = host_kvm->arch.vgic.vgic_model;
+
 	if (test_bit(KVM_ARCH_FLAG_MTE_ENABLED, &host_kvm->arch.flags))
 		set_bit(KVM_ARCH_FLAG_MTE_ENABLED, &kvm->arch.flags);
 
diff --git a/arch/arm64/kvm/hyp/nvhe/sys_regs.c b/arch/arm64/kvm/hyp/nvhe/sys_regs.c
index 82da9b03692d4..3108b5185c204 100644
--- a/arch/arm64/kvm/hyp/nvhe/sys_regs.c
+++ b/arch/arm64/kvm/hyp/nvhe/sys_regs.c
@@ -444,6 +444,8 @@ static const struct sys_reg_desc pvm_sys_reg_descs[] = {
 
 	/* Scalable Vector Registers are restricted. */
 
+	HOST_HANDLED(SYS_ICC_PMR_EL1),
+
 	RAZ_WI(SYS_ERRIDR_EL1),
 	RAZ_WI(SYS_ERRSELR_EL1),
 	RAZ_WI(SYS_ERXFR_EL1),
@@ -457,9 +459,12 @@ static const struct sys_reg_desc pvm_sys_reg_descs[] = {
 
 	/* Limited Ordering Regions Registers are restricted. */
 
+	HOST_HANDLED(SYS_ICC_DIR_EL1),
+	HOST_HANDLED(SYS_ICC_RPR_EL1),
 	HOST_HANDLED(SYS_ICC_SGI1R_EL1),
 	HOST_HANDLED(SYS_ICC_ASGI1R_EL1),
 	HOST_HANDLED(SYS_ICC_SGI0R_EL1),
+	HOST_HANDLED(SYS_ICC_CTLR_EL1),
 	{ SYS_DESC(SYS_ICC_SRE_EL1), .access = pvm_gic_read_sre, },
 
 	HOST_HANDLED(SYS_CCSIDR_EL1),

Thanks,

	M.

-- 
Without deviation from the norm, progress is not possible.