[RFC 11/55] KVM: arm64: Emulate taking an exception to the guest hypervisor

[Jintack Lim]

Emulate taking an exception to the guest hypervisor running in the
virtual EL2 as described in ARM ARM AArch64.TakeException().

Signed-off-by: Jintack Lim <jintack at cs.columbia.edu>
---
 arch/arm/include/asm/kvm_emulate.h   | 14 ++++++++
 arch/arm64/include/asm/kvm_emulate.h | 19 +++++++++++
 arch/arm64/kvm/Makefile              |  2 ++
 arch/arm64/kvm/emulate-nested.c      | 66 ++++++++++++++++++++++++++++++++++++
 arch/arm64/kvm/trace.h               | 20 +++++++++++
 5 files changed, 121 insertions(+)
 create mode 100644 arch/arm64/kvm/emulate-nested.c

diff --git a/arch/arm/include/asm/kvm_emulate.h b/arch/arm/include/asm/kvm_emulate.h
index 0a03b7d..0fa2f5a 100644
--- a/arch/arm/include/asm/kvm_emulate.h
+++ b/arch/arm/include/asm/kvm_emulate.h
@@ -47,6 +47,20 @@ static inline void vcpu_set_reg(struct kvm_vcpu *vcpu, u8 reg_num,
 void kvm_inject_dabt(struct kvm_vcpu *vcpu, unsigned long addr);
 void kvm_inject_pabt(struct kvm_vcpu *vcpu, unsigned long addr);
 
+static inline int kvm_inject_nested_sync(struct kvm_vcpu *vcpu, u64 esr_el2)
+{
+	kvm_err("Unexpected call to %s for the non-nesting configuration\n",
+		 __func__);
+	return -EINVAL;
+}
+
+static inline int kvm_inject_nested_irq(struct kvm_vcpu *vcpu)
+{
+	kvm_err("Unexpected call to %s for the non-nesting configuration\n",
+		 __func__);
+	return -EINVAL;
+}
+
 static inline void kvm_arm_setup_shadow_state(struct kvm_vcpu *vcpu) { };
 static inline void kvm_arm_restore_shadow_state(struct kvm_vcpu *vcpu) { };
 static inline void kvm_arm_init_cpu_context(kvm_cpu_context_t *cpu_ctxt) { };
diff --git a/arch/arm64/include/asm/kvm_emulate.h b/arch/arm64/include/asm/kvm_emulate.h
index 8892c82..0987ee4 100644
--- a/arch/arm64/include/asm/kvm_emulate.h
+++ b/arch/arm64/include/asm/kvm_emulate.h
@@ -42,6 +42,25 @@
 void kvm_inject_dabt(struct kvm_vcpu *vcpu, unsigned long addr);
 void kvm_inject_pabt(struct kvm_vcpu *vcpu, unsigned long addr);
 
+#ifdef CONFIG_KVM_ARM_NESTED_HYP
+int kvm_inject_nested_sync(struct kvm_vcpu *vcpu, u64 esr_el2);
+int kvm_inject_nested_irq(struct kvm_vcpu *vcpu);
+#else
+static inline int kvm_inject_nested_sync(struct kvm_vcpu *vcpu, u64 esr_el2)
+{
+	kvm_err("Unexpected call to %s for the non-nesting configuration\n",
+		 __func__);
+	return -EINVAL;
+}
+
+static inline int kvm_inject_nested_irq(struct kvm_vcpu *vcpu)
+{
+	kvm_err("Unexpected call to %s for the non-nesting configuration\n",
+		 __func__);
+	return -EINVAL;
+}
+#endif
+
 void kvm_arm_setup_shadow_state(struct kvm_vcpu *vcpu);
 void kvm_arm_restore_shadow_state(struct kvm_vcpu *vcpu);
 void kvm_arm_init_cpu_context(kvm_cpu_context_t *cpu_ctxt);
diff --git a/arch/arm64/kvm/Makefile b/arch/arm64/kvm/Makefile
index 7811d27..b342bdd 100644
--- a/arch/arm64/kvm/Makefile
+++ b/arch/arm64/kvm/Makefile
@@ -34,3 +34,5 @@ kvm-$(CONFIG_KVM_ARM_HOST) += $(KVM)/arm/vgic/vgic-its.o
 kvm-$(CONFIG_KVM_ARM_HOST) += $(KVM)/irqchip.o
 kvm-$(CONFIG_KVM_ARM_HOST) += $(KVM)/arm/arch_timer.o
 kvm-$(CONFIG_KVM_ARM_PMU) += $(KVM)/arm/pmu.o
+
+kvm-$(CONFIG_KVM_ARM_NESTED_HYP) += emulate-nested.o
diff --git a/arch/arm64/kvm/emulate-nested.c b/arch/arm64/kvm/emulate-nested.c
new file mode 100644
index 0000000..59d147f
--- /dev/null
+++ b/arch/arm64/kvm/emulate-nested.c
@@ -0,0 +1,66 @@
+/*
+ * Copyright (C) 2016 - Columbia University
+ * Author: Jintack Lim <jintack at cs.columbia.edu>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/kvm.h>
+#include <linux/kvm_host.h>
+
+#include <asm/kvm_emulate.h>
+
+#include "trace.h"
+
+#define	EL2_EXCEPT_SYNC_OFFSET	0x400
+#define	EL2_EXCEPT_ASYNC_OFFSET	0x480
+
+
+/*
+ *  Emulate taking an exception. See ARM ARM J8.1.2 AArch64.TakeException()
+ */
+static int kvm_inject_nested(struct kvm_vcpu *vcpu, u64 esr_el2,
+			     int exception_offset)
+{
+	int ret = 1;
+	kvm_cpu_context_t *ctxt = &vcpu->arch.ctxt;
+
+	/* We don't inject an exception recursively to virtual EL2 */
+	if (vcpu_mode_el2(vcpu))
+		BUG();
+
+	ctxt->el2_regs[SPSR_EL2] = *vcpu_cpsr(vcpu);
+	ctxt->el2_regs[ELR_EL2] = *vcpu_pc(vcpu);
+	ctxt->el2_regs[ESR_EL2] = esr_el2;
+
+	/* On an exception, PSTATE.SP = 1 */
+	*vcpu_cpsr(vcpu) = PSR_MODE_EL2h;
+	*vcpu_cpsr(vcpu) |=  (PSR_A_BIT | PSR_F_BIT | PSR_I_BIT | PSR_D_BIT);
+	*vcpu_pc(vcpu) = ctxt->el2_regs[VBAR_EL2] + exception_offset;
+
+	trace_kvm_inject_nested_exception(vcpu, esr_el2, *vcpu_pc(vcpu));
+
+	return ret;
+}
+
+int kvm_inject_nested_sync(struct kvm_vcpu *vcpu, u64 esr_el2)
+{
+	return kvm_inject_nested(vcpu, esr_el2, EL2_EXCEPT_SYNC_OFFSET);
+}
+
+int kvm_inject_nested_irq(struct kvm_vcpu *vcpu)
+{
+	u64 esr_el2 = kvm_vcpu_get_hsr(vcpu);
+	/* We supports only IRQ and FIQ, so the esr_el2 is not updated. */
+	return kvm_inject_nested(vcpu, esr_el2, EL2_EXCEPT_ASYNC_OFFSET);
+}
diff --git a/arch/arm64/kvm/trace.h b/arch/arm64/kvm/trace.h
index 7fb0008..7c86cfb 100644
--- a/arch/arm64/kvm/trace.h
+++ b/arch/arm64/kvm/trace.h
@@ -167,6 +167,26 @@
 );
 
 
+TRACE_EVENT(kvm_inject_nested_exception,
+	TP_PROTO(struct kvm_vcpu *vcpu, unsigned long esr_el2,
+		 unsigned long pc),
+	TP_ARGS(vcpu, esr_el2, pc),
+
+	TP_STRUCT__entry(
+		__field(struct kvm_vcpu *,	vcpu)
+		__field(unsigned long,		esr_el2)
+		__field(unsigned long,		pc)
+	),
+
+	TP_fast_assign(
+		__entry->vcpu = vcpu;
+		__entry->esr_el2 = esr_el2;
+		__entry->pc = pc;
+	),
+
+	TP_printk("vcpu: %p, inject exception to vEL2: ESR_EL2 0x%lx, vector: 0x%016lx",
+		  __entry->vcpu, __entry->esr_el2, __entry->pc)
+);
 #endif /* _TRACE_ARM64_KVM_H */
 
 #undef TRACE_INCLUDE_PATH
-- 
1.9.1