From:   Steven Price <steven.price@arm.com>
To:     kvm@vger.kernel.org, kvmarm@lists.linux.dev
Cc:     Steven Price <steven.price@arm.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Marc Zyngier <maz@kernel.org>, Will Deacon <will@kernel.org>,
        James Morse <james.morse@arm.com>,
        Oliver Upton <oliver.upton@linux.dev>,
        Suzuki K Poulose <suzuki.poulose@arm.com>,
        Zenghui Yu <yuzenghui@huawei.com>,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        Joey Gouly <joey.gouly@arm.com>,
        Alexandru Elisei <alexandru.elisei@arm.com>,
        Christoffer Dall <christoffer.dall@arm.com>,
        Fuad Tabba <tabba@google.com>, linux-coco@lists.linux.dev
Subject: [RFC PATCH 11/28] arm64: RME: Support for the VGIC in realms
Date:   Fri, 27 Jan 2023 11:29:15 +0000
Message-Id: <20230127112932.38045-12-steven.price@arm.com>
In-Reply-To: <20230127112932.38045-1-steven.price@arm.com>
References: <20230127112248.136810-1-suzuki.poulose@arm.com>
 <20230127112932.38045-1-steven.price@arm.com>
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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>
---
 arch/arm64/kvm/arm.c          | 15 +++++++++++---
 arch/arm64/kvm/vgic/vgic-v3.c |  9 +++++++--
 arch/arm64/kvm/vgic/vgic.c    | 37 +++++++++++++++++++++++++++++++++--
 3 files changed, 54 insertions(+), 7 deletions(-)

diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 52affed2f3cf..1b2547516f62 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -475,17 +475,22 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
 
 void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
 {
+	kvm_timer_vcpu_put(vcpu);
+	kvm_vgic_put(vcpu);
+
+	vcpu->cpu = -1;
+
+	if (vcpu_is_rec(vcpu))
+		return;
+
 	kvm_arch_vcpu_put_debug_state_flags(vcpu);
 	kvm_arch_vcpu_put_fp(vcpu);
 	if (has_vhe())
 		kvm_vcpu_put_sysregs_vhe(vcpu);
-	kvm_timer_vcpu_put(vcpu);
-	kvm_vgic_put(vcpu);
 	kvm_vcpu_pmu_restore_host(vcpu);
 	kvm_arm_vmid_clear_active();
 
 	vcpu_clear_on_unsupported_cpu(vcpu);
-	vcpu->cpu = -1;
 }
 
 void kvm_arm_vcpu_power_off(struct kvm_vcpu *vcpu)
@@ -623,6 +628,10 @@ int kvm_arch_vcpu_run_pid_change(struct kvm_vcpu *vcpu)
 	}
 
 	if (!irqchip_in_kernel(kvm)) {
+		/* Userspace irqchip not yet supported with Realms */
+		if (kvm_is_realm(vcpu->kvm))
+			return -EOPNOTSUPP;
+
 		/*
 		 * Tell the rest of the code that there are userspace irqchip
 		 * VMs in the wild.
diff --git a/arch/arm64/kvm/vgic/vgic-v3.c b/arch/arm64/kvm/vgic/vgic-v3.c
index 826ff6f2a4e7..121c7a68c397 100644
--- a/arch/arm64/kvm/vgic/vgic-v3.c
+++ b/arch/arm64/kvm/vgic/vgic-v3.c
@@ -6,9 +6,11 @@
 #include <linux/kvm.h>
 #include <linux/kvm_host.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"
 
@@ -669,7 +671,8 @@ int vgic_v3_probe(const struct gic_kvm_info *info)
 			(unsigned long long)info->vcpu.start);
 	} else if (kvm_get_mode() != KVM_MODE_PROTECTED) {
 		kvm_vgic_global_state.vcpu_base = info->vcpu.start;
-		kvm_vgic_global_state.can_emulate_gicv2 = true;
+		if (!static_branch_unlikely(&kvm_rme_is_available))
+			kvm_vgic_global_state.can_emulate_gicv2 = true;
 		ret = kvm_register_vgic_device(KVM_DEV_TYPE_ARM_VGIC_V2);
 		if (ret) {
 			kvm_err("Cannot register GICv2 KVM device.\n");
@@ -744,7 +747,9 @@ void vgic_v3_vmcr_sync(struct kvm_vcpu *vcpu)
 {
 	struct vgic_v3_cpu_if *cpu_if = &vcpu->arch.vgic_cpu.vgic_v3;
 
-	if (likely(cpu_if->vgic_sre))
+	if (vcpu_is_rec(vcpu))
+		cpu_if->vgic_vmcr = vcpu->arch.rec.run->exit.gicv3_vmcr;
+	else if (likely(cpu_if->vgic_sre))
 		cpu_if->vgic_vmcr = kvm_call_hyp_ret(__vgic_v3_read_vmcr);
 }
 
diff --git a/arch/arm64/kvm/vgic/vgic.c b/arch/arm64/kvm/vgic/vgic.c
index d97e6080b421..bc77660f7051 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/rmi_smc.h>
 
 #include "vgic.h"
 
@@ -848,10 +850,23 @@ 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_vgic_global_state.nr_lr; i++) {
+		cpu_if->vgic_lr[i] = vcpu->arch.rec.run->exit.gicv3_lrs[i];
+		vcpu->arch.rec.run->entry.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);
 }
@@ -878,10 +893,28 @@ 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_vgic_global_state.nr_lr; i++) {
+		vcpu->arch.rec.run->entry.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);
 }
@@ -922,7 +955,7 @@ void kvm_vgic_flush_hwstate(struct kvm_vcpu *vcpu)
 
 void kvm_vgic_load(struct kvm_vcpu *vcpu)
 {
-	if (unlikely(!vgic_initialized(vcpu->kvm)))
+	if (unlikely(!vgic_initialized(vcpu->kvm)) || vcpu_is_rec(vcpu))
 		return;
 
 	if (kvm_vgic_global_state.type == VGIC_V2)
@@ -933,7 +966,7 @@ void kvm_vgic_load(struct kvm_vcpu *vcpu)
 
 void kvm_vgic_put(struct kvm_vcpu *vcpu)
 {
-	if (unlikely(!vgic_initialized(vcpu->kvm)))
+	if (unlikely(!vgic_initialized(vcpu->kvm)) || vcpu_is_rec(vcpu))
 		return;
 
 	if (kvm_vgic_global_state.type == VGIC_V2)
-- 
2.34.1