KVM: arm64: gic-v5: Probe for GICv5

Add in a probe function for GICv5 which enables support for GICv3
guests on a GICv5 host, if FEAT_GCIE_LEGACY is supported by the
hardware.

Co-authored-by: Timothy Hayes <timothy.hayes@arm.com>
Signed-off-by: Timothy Hayes <timothy.hayes@arm.com>
Signed-off-by: Sascha Bischoff <sascha.bischoff@arm.com>
Link: https://lore.kernel.org/r/20250627100847.1022515-6-sascha.bischoff@arm.com
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>

diff --git a/arch/arm64/kvm/Makefile b/arch/arm64/kvm/Makefile
index 7c329e01c557ab882cdb3a701a7682d18d8bd73d..3ebc0570345cc011830eea0a0472619e00e28056 100644 (file)
--- a/arch/arm64/kvm/Makefile
+++ b/arch/arm64/kvm/Makefile
@@ -23,7 +23,8 @@ kvm-y += arm.o mmu.o mmio.o psci.o hypercalls.o pvtime.o \
         vgic/vgic-v3.o vgic/vgic-v4.o \
         vgic/vgic-mmio.o vgic/vgic-mmio-v2.o \
         vgic/vgic-mmio-v3.o vgic/vgic-kvm-device.o \
-        vgic/vgic-its.o vgic/vgic-debug.o vgic/vgic-v3-nested.o
+        vgic/vgic-its.o vgic/vgic-debug.o vgic/vgic-v3-nested.o \
+        vgic/vgic-v5.o
 
 kvm-$(CONFIG_HW_PERF_EVENTS)  += pmu-emul.o pmu.o
 kvm-$(CONFIG_ARM64_PTR_AUTH)  += pauth.o

diff --git a/arch/arm64/kvm/vgic/vgic-init.c b/arch/arm64/kvm/vgic/vgic-init.c
index 1f1f0c9ce64faa922e7bc0b9d042c48d3c5e342a..72442c825d1999111a33ac975237c0344c5175ce 100644 (file)
--- a/arch/arm64/kvm/vgic/vgic-init.c
+++ b/arch/arm64/kvm/vgic/vgic-init.c
@@ -724,6 +724,9 @@ int kvm_vgic_hyp_init(void)
                        kvm_info("GIC system register CPU interface enabled\n");
                }
                break;
+       case GIC_V5:
+               ret = vgic_v5_probe(gic_kvm_info);
+               break;
        default:
                ret = -ENODEV;
        }

diff --git a/arch/arm64/kvm/vgic/vgic-v5.c b/arch/arm64/kvm/vgic/vgic-v5.c
new file mode 100644 (file)
index 0000000..6bdbb22
--- /dev/null
+++ b/arch/arm64/kvm/vgic/vgic-v5.c
@@ -0,0 +1,52 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <kvm/arm_vgic.h>
+#include <linux/irqchip/arm-vgic-info.h>
+
+#include "vgic.h"
+
+/*
+ * Probe for a vGICv5 compatible interrupt controller, returning 0 on success.
+ * Currently only supports GICv3-based VMs on a GICv5 host, and hence only
+ * registers a VGIC_V3 device.
+ */
+int vgic_v5_probe(const struct gic_kvm_info *info)
+{
+       u64 ich_vtr_el2;
+       int ret;
+
+       if (!info->has_gcie_v3_compat)
+               return -ENODEV;
+
+       kvm_vgic_global_state.type = VGIC_V5;
+       kvm_vgic_global_state.has_gcie_v3_compat = true;
+
+       /* We only support v3 compat mode - use vGICv3 limits */
+       kvm_vgic_global_state.max_gic_vcpus = VGIC_V3_MAX_CPUS;
+
+       kvm_vgic_global_state.vcpu_base = 0;
+       kvm_vgic_global_state.vctrl_base = NULL;
+       kvm_vgic_global_state.can_emulate_gicv2 = false;
+       kvm_vgic_global_state.has_gicv4 = false;
+       kvm_vgic_global_state.has_gicv4_1 = false;
+
+       ich_vtr_el2 =  kvm_call_hyp_ret(__vgic_v3_get_gic_config);
+       kvm_vgic_global_state.ich_vtr_el2 = (u32)ich_vtr_el2;
+
+       /*
+        * The ListRegs field is 5 bits, but there is an architectural
+        * maximum of 16 list registers. Just ignore bit 4...
+        */
+       kvm_vgic_global_state.nr_lr = (ich_vtr_el2 & 0xf) + 1;
+
+       ret = kvm_register_vgic_device(KVM_DEV_TYPE_ARM_VGIC_V3);
+       if (ret) {
+               kvm_err("Cannot register GICv3-legacy KVM device.\n");
+               return ret;
+       }
+
+       static_branch_enable(&kvm_vgic_global_state.gicv3_cpuif);
+       kvm_info("GCIE legacy system register CPU interface\n");
+
+       return 0;
+}

diff --git a/arch/arm64/kvm/vgic/vgic.h b/arch/arm64/kvm/vgic/vgic.h
index 23d39399808569fbb1f29d03abe052430d9c5356..4f1e123b063e2056b361b97c9caf09c7967f023e 100644 (file)
--- a/arch/arm64/kvm/vgic/vgic.h
+++ b/arch/arm64/kvm/vgic/vgic.h
@@ -308,6 +308,8 @@ int vgic_init(struct kvm *kvm);
 void vgic_debug_init(struct kvm *kvm);
 void vgic_debug_destroy(struct kvm *kvm);
 
+int vgic_v5_probe(const struct gic_kvm_info *info);
+
 static inline int vgic_v3_max_apr_idx(struct kvm_vcpu *vcpu)
 {
        struct vgic_cpu *cpu_if = &vcpu->arch.vgic_cpu;