[PATCH v7 14/45] arm64: RME: Support for the VGIC in realms

Steven Price
2025-02-13T16:15:45Z

The RMM provides emulation of a VGIC to the realm guest but delegates
much of the handling to the host. Implement support in KVM for
saving/restoring state to/from the REC structure.

Signed-off-by: Steven Price <steven.price@arm.com>
---
Changes from v5:
* Handle RMM providing fewer GIC LRs than the hardware supports.
---
arch/arm64/include/asm/kvm_rme.h | 1 +
arch/arm64/kvm/arm.c | 16 +++++++++---
arch/arm64/kvm/rme.c | 5 ++++
arch/arm64/kvm/vgic/vgic-init.c | 2 +-
arch/arm64/kvm/vgic/vgic-v3.c | 5 ++++
arch/arm64/kvm/vgic/vgic.c | 43 ++++++++++++++++++++++++++++++--
6 files changed, 66 insertions(+), 6 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_rme.h b/arch/arm64/include/asm/kvm_rme.h
index 5db377943db4..2e319db9a05f 100644
--- a/arch/arm64/include/asm/kvm_rme.h
+++ b/arch/arm64/include/asm/kvm_rme.h
@@ -83,6 +83,7 @@ struct realm_rec {

void kvm_init_rme(void);
u32 kvm_realm_ipa_limit(void);
+u32 kvm_realm_vgic_nr_lr(void);

int kvm_realm_enable_cap(struct kvm *kvm, struct kvm_enable_cap *cap);
int kvm_init_realm_vm(struct kvm *kvm);
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index a6a3034a2f50..a2bc86b3798f 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -672,19 +672,24 @@ void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
kvm_call_hyp_nvhe(__pkvm_vcpu_put);
}

+ kvm_timer_vcpu_put(vcpu);
+ kvm_vgic_put(vcpu);
+
+ vcpu->cpu = -1;
+
+ if (vcpu_is_rec(vcpu))
+ return;
+
kvm_vcpu_put_debug(vcpu);
kvm_arch_vcpu_put_fp(vcpu);
if (has_vhe())
kvm_vcpu_put_vhe(vcpu);
- kvm_timer_vcpu_put(vcpu);
- kvm_vgic_put(vcpu);
kvm_vcpu_pmu_restore_host(vcpu);
if (vcpu_has_nv(vcpu))
kvm_vcpu_put_hw_mmu(vcpu);
kvm_arm_vmid_clear_active();

vcpu_clear_on_unsupported_cpu(vcpu);
- vcpu->cpu = -1;
}

static void __kvm_arm_vcpu_power_off(struct kvm_vcpu *vcpu)
@@ -889,6 +894,11 @@ int kvm_arch_vcpu_run_pid_change(struct kvm_vcpu *vcpu)
return ret;
}

+ if (!irqchip_in_kernel(kvm) && kvm_is_realm(vcpu->kvm)) {
+ /* Userspace irqchip not yet supported with Realms */
+ return -EOPNOTSUPP;
+ }
+
mutex_lock(&kvm->arch.config_lock);
set_bit(KVM_ARCH_FLAG_HAS_RAN_ONCE, &kvm->arch.flags);
mutex_unlock(&kvm->arch.config_lock);
diff --git a/arch/arm64/kvm/rme.c b/arch/arm64/kvm/rme.c
index 0aa1f29b0610..195390a66bc4 100644
--- a/arch/arm64/kvm/rme.c
+++ b/arch/arm64/kvm/rme.c
@@ -77,6 +77,11 @@ u32 kvm_realm_ipa_limit(void)
return u64_get_bits(rmm_feat_reg0, RMI_FEATURE_REGISTER_0_S2SZ);
}

+u32 kvm_realm_vgic_nr_lr(void)
+{
+ return u64_get_bits(rmm_feat_reg0, RMI_FEATURE_REGISTER_0_GICV3_NUM_LRS);
+}
+
static int get_start_level(struct realm *realm)
{
return 4 - ((realm->ia_bits - 8) / (RMM_PAGE_SHIFT - 3));
diff --git a/arch/arm64/kvm/vgic/vgic-init.c b/arch/arm64/kvm/vgic/vgic-init.c
index bc7e22ab5d81..0ec9f6f62e86 100644
--- a/arch/arm64/kvm/vgic/vgic-init.c
+++ b/arch/arm64/kvm/vgic/vgic-init.c
@@ -79,7 +79,7 @@ int kvm_vgic_create(struct kvm *kvm, u32 type)
* the proper checks already.
*/
if (type == KVM_DEV_TYPE_ARM_VGIC_V2 &&
- !kvm_vgic_global_state.can_emulate_gicv2)
+ (!kvm_vgic_global_state.can_emulate_gicv2 || kvm_is_realm(kvm)))
return -ENODEV;

/* Must be held to avoid race with vCPU creation */
diff --git a/arch/arm64/kvm/vgic/vgic-v3.c b/arch/arm64/kvm/vgic/vgic-v3.c
index d7233ab982d0..41c3de063e72 100644
--- a/arch/arm64/kvm/vgic/vgic-v3.c
+++ b/arch/arm64/kvm/vgic/vgic-v3.c
@@ -8,9 +8,11 @@
#include <linux/kvm_host.h>
#include <linux/string_choices.h>
#include <kvm/arm_vgic.h>
+#include <asm/kvm_emulate.h>
#include <asm/kvm_hyp.h>
#include <asm/kvm_mmu.h>
#include <asm/kvm_asm.h>
+#include <asm/rmi_smc.h>

#include "vgic.h"

@@ -748,6 +750,9 @@ void vgic_v3_put(struct kvm_vcpu *vcpu)
{
struct vgic_v3_cpu_if *cpu_if = &vcpu->arch.vgic_cpu.vgic_v3;

+ if (vcpu_is_rec(vcpu))
+ cpu_if->vgic_vmcr = vcpu->arch.rec.run->exit.gicv3_vmcr;
+
if (likely(!is_protected_kvm_enabled()))
kvm_call_hyp(__vgic_v3_save_vmcr_aprs, cpu_if);
WARN_ON(vgic_v4_put(vcpu));
diff --git a/arch/arm64/kvm/vgic/vgic.c b/arch/arm64/kvm/vgic/vgic.c
index 1077fab2df4b..4218de3ea9da 100644
--- a/arch/arm64/kvm/vgic/vgic.c
+++ b/arch/arm64/kvm/vgic/vgic.c
@@ -10,7 +10,9 @@
#include <linux/list_sort.h>
#include <linux/nospec.h>

+#include <asm/kvm_emulate.h>
#include <asm/kvm_hyp.h>
+#include <asm/kvm_rme.h>

#include "vgic.h"

@@ -23,6 +25,8 @@ struct vgic_global kvm_vgic_global_state __ro_after_init = {

static inline int kvm_vcpu_vgic_nr_lr(struct kvm_vcpu *vcpu)
{
+ if (unlikely(vcpu_is_rec(vcpu)))
+ return kvm_realm_vgic_nr_lr();
return kvm_vgic_global_state.nr_lr;
}

@@ -864,10 +868,23 @@ static inline bool can_access_vgic_from_kernel(void)
return !static_branch_unlikely(&kvm_vgic_global_state.gicv3_cpuif) || has_vhe();
}

+static inline void vgic_rmm_save_state(struct kvm_vcpu *vcpu)
+{
+ struct vgic_v3_cpu_if *cpu_if = &vcpu->arch.vgic_cpu.vgic_v3;
+ int i;
+
+ for (i = 0; i < kvm_vcpu_vgic_nr_lr(vcpu); i++) {
+ cpu_if->vgic_lr[i] = vcpu->arch.rec.run->exit.gicv3_lrs[i];
+ vcpu->arch.rec.run->enter.gicv3_lrs[i] = 0;
+ }
+}
+
static inline void vgic_save_state(struct kvm_vcpu *vcpu)
{
if (!static_branch_unlikely(&kvm_vgic_global_state.gicv3_cpuif))
vgic_v2_save_state(vcpu);
+ else if (vcpu_is_rec(vcpu))
+ vgic_rmm_save_state(vcpu);
else
__vgic_v3_save_state(&vcpu->arch.vgic_cpu.vgic_v3);
}
@@ -894,10 +911,28 @@ void kvm_vgic_sync_hwstate(struct kvm_vcpu *vcpu)
vgic_prune_ap_list(vcpu);
}

+static inline void vgic_rmm_restore_state(struct kvm_vcpu *vcpu)
+{
+ struct vgic_v3_cpu_if *cpu_if = &vcpu->arch.vgic_cpu.vgic_v3;
+ int i;
+
+ for (i = 0; i < kvm_vcpu_vgic_nr_lr(vcpu); i++) {
+ vcpu->arch.rec.run->enter.gicv3_lrs[i] = cpu_if->vgic_lr[i];
+ /*
+ * Also populate the rec.run->exit copies so that a late
+ * decision to back out from entering the realm doesn't cause
+ * the state to be lost
+ */
+ vcpu->arch.rec.run->exit.gicv3_lrs[i] = cpu_if->vgic_lr[i];
+ }
+}
+
static inline void vgic_restore_state(struct kvm_vcpu *vcpu)
{
if (!static_branch_unlikely(&kvm_vgic_global_state.gicv3_cpuif))
vgic_v2_restore_state(vcpu);
+ else if (vcpu_is_rec(vcpu))
+ vgic_rmm_restore_state(vcpu);
else
__vgic_v3_restore_state(&vcpu->arch.vgic_cpu.vgic_v3);
}
@@ -938,7 +973,9 @@ void kvm_vgic_flush_hwstate(struct kvm_vcpu *vcpu)

void kvm_vgic_load(struct kvm_vcpu *vcpu)
{
- if (unlikely(!irqchip_in_kernel(vcpu->kvm) || !vgic_initialized(vcpu->kvm))) {
+ if (unlikely(!irqchip_in_kernel(vcpu->kvm) ||
+ !vgic_initialized(vcpu->kvm) ||
+ vcpu_is_rec(vcpu))) {
if (has_vhe() && static_branch_unlikely(&kvm_vgic_global_state.gicv3_cpuif))
__vgic_v3_activate_traps(&vcpu->arch.vgic_cpu.vgic_v3);
return;
@@ -952,7 +989,9 @@ void kvm_vgic_load(struct kvm_vcpu *vcpu)

void kvm_vgic_put(struct kvm_vcpu *vcpu)
{
- if (unlikely(!irqchip_in_kernel(vcpu->kvm) || !vgic_initialized(vcpu->kvm))) {
+ if (unlikely(!irqchip_in_kernel(vcpu->kvm) ||
+ !vgic_initialized(vcpu->kvm) ||
+ vcpu_is_rec(vcpu))) {
if (has_vhe() && static_branch_unlikely(&kvm_vgic_global_state.gicv3_cpuif))
__vgic_v3_deactivate_traps(&vcpu->arch.vgic_cpu.vgic_v3);
return;
--
2.43.0