KVM: ARM: Emulation framework and CP15 emulation

Adds a new important function in the main KVM/ARM code called
handle_exit() which is called from kvm_arch_vcpu_ioctl_run() on returns
from guest execution. This function examines the Hyp-Syndrome-Register
(HSR), which contains information telling KVM what caused the exit from
the guest.

Some of the reasons for an exit are CP15 accesses, which are
not allowed from the guest and this commit handles these exits by
emulating the intended operation in software and skipping the guest
instruction.

Minor notes about the coproc register reset:
1) We reserve a value of 0 as an invalid cp15 offset, to catch bugs in our
   table, at cost of 4 bytes per vcpu.

2) Added comments on the table indicating how we handle each register, for
   simplicity of understanding.

Reviewed-by: Will Deacon <will.deacon@arm.com>
Reviewed-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Christoffer Dall <c.dall@virtualopensystems.com>

1 files changed, 65 insertions, 0 deletions

diff --git a/arch/arm/kvm/trace.h b/arch/arm/kvm/trace.h
index 105d1f79909..022305b38c2 100644
--- a/arch/arm/kvm/trace.h
+++ b/arch/arm/kvm/trace.h
@@ -64,6 +64,51 @@ TRACE_EVENT(kvm_irq_line,
 		  __entry->type, __entry->vcpu_idx, __entry->irq_num, __entry->level)
 );
 
+/* Architecturally implementation defined CP15 register access */
+TRACE_EVENT(kvm_emulate_cp15_imp,
+	TP_PROTO(unsigned long Op1, unsigned long Rt1, unsigned long CRn,
+		 unsigned long CRm, unsigned long Op2, bool is_write),
+	TP_ARGS(Op1, Rt1, CRn, CRm, Op2, is_write),
+
+	TP_STRUCT__entry(
+		__field(	unsigned int,	Op1		)
+		__field(	unsigned int,	Rt1		)
+		__field(	unsigned int,	CRn		)
+		__field(	unsigned int,	CRm		)
+		__field(	unsigned int,	Op2		)
+		__field(	bool,		is_write	)
+	),
+
+	TP_fast_assign(
+		__entry->is_write		= is_write;
+		__entry->Op1			= Op1;
+		__entry->Rt1			= Rt1;
+		__entry->CRn			= CRn;
+		__entry->CRm			= CRm;
+		__entry->Op2			= Op2;
+	),
+
+	TP_printk("Implementation defined CP15: %s\tp15, %u, r%u, c%u, c%u, %u",
+			(__entry->is_write) ? "mcr" : "mrc",
+			__entry->Op1, __entry->Rt1, __entry->CRn,
+			__entry->CRm, __entry->Op2)
+);
+
+TRACE_EVENT(kvm_wfi,
+	TP_PROTO(unsigned long vcpu_pc),
+	TP_ARGS(vcpu_pc),
+
+	TP_STRUCT__entry(
+		__field(	unsigned long,	vcpu_pc		)
+	),
+
+	TP_fast_assign(
+		__entry->vcpu_pc		= vcpu_pc;
+	),
+
+	TP_printk("guest executed wfi at: 0x%08lx", __entry->vcpu_pc)
+);
+
 TRACE_EVENT(kvm_unmap_hva,
 	TP_PROTO(unsigned long hva),
 	TP_ARGS(hva),
@@ -112,6 +157,26 @@ TRACE_EVENT(kvm_set_spte_hva,
 	TP_printk("mmu notifier set pte hva: %#08lx", __entry->hva)
 );
 
+TRACE_EVENT(kvm_hvc,
+	TP_PROTO(unsigned long vcpu_pc, unsigned long r0, unsigned long imm),
+	TP_ARGS(vcpu_pc, r0, imm),
+
+	TP_STRUCT__entry(
+		__field(	unsigned long,	vcpu_pc		)
+		__field(	unsigned long,	r0		)
+		__field(	unsigned long,	imm		)
+	),
+
+	TP_fast_assign(
+		__entry->vcpu_pc		= vcpu_pc;
+		__entry->r0		= r0;
+		__entry->imm		= imm;
+	),
+
+	TP_printk("HVC at 0x%08lx (r0: 0x%08lx, imm: 0x%lx",
+		  __entry->vcpu_pc, __entry->r0, __entry->imm)
+);
+
 #endif /* _TRACE_KVM_H */
 
 #undef TRACE_INCLUDE_PATH