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

Jintack Lim [off-list ref] writes:

Compilation on 32bit arm architecture will fail without them.

...

quoted

It seems these functions are
defined separately in 32/64 bit specific header files. Or is it that
64 bit compilation also depends on the 32 bit header file ?

It's only for 32bit architecture. For example, kvm_inject_nested_irq()
is called in virt/kvm/arm/vgic/vgic.c which is shared between 32 and
64 bit.

Ah, that's the catch! Thanks for clearing this up!

quoted

Bandan

quoted

Thanks,
Jintack

quoted

Bandan

quoted

 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@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

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