KVM: LoongArch: selftests: Add exception handler register interface

Add interrupt and exception handler register interface. When exception
happens, execute registered exception handler if exists, else report an
error.

Signed-off-by: Bibo Mao <maobibo@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

2 files changed, 45 insertions, 0 deletions

diff --git a/tools/testing/selftests/kvm/include/loongarch/processor.h b/tools/testing/selftests/kvm/include/loongarch/processor.h
index f1bfc06a2264..a1930f28e044 100644
--- a/tools/testing/selftests/kvm/include/loongarch/processor.h
+++ b/tools/testing/selftests/kvm/include/loongarch/processor.h
@@ -84,6 +84,11 @@
 #define LOONGARCH_CSR_EUEN		0x2
 #define LOONGARCH_CSR_ECFG		0x4
 #define LOONGARCH_CSR_ESTAT		0x5  /* Exception status */
+#define  CSR_ESTAT_EXC_SHIFT		16
+#define  CSR_ESTAT_EXC_WIDTH		6
+#define  CSR_ESTAT_EXC			(0x3f << CSR_ESTAT_EXC_SHIFT)
+#define    EXCCODE_INT			0    /* Interrupt */
+#define      INT_TI			11   /* Timer interrupt*/
 #define LOONGARCH_CSR_ERA		0x6  /* ERA */
 #define LOONGARCH_CSR_BADV		0x7  /* Bad virtual address */
 #define LOONGARCH_CSR_EENTRY		0xc
@@ -155,6 +160,17 @@ struct ex_regs {
 #define PRMD_OFFSET_EXREGS		offsetof(struct ex_regs, prmd)
 #define EXREGS_SIZE			sizeof(struct ex_regs)
 
+#define VECTOR_NUM			64
+
+typedef void(*handler_fn)(struct ex_regs *);
+
+struct handlers {
+	handler_fn exception_handlers[VECTOR_NUM];
+};
+
+void vm_init_descriptor_tables(struct kvm_vm *vm);
+void vm_install_exception_handler(struct kvm_vm *vm, int vector, handler_fn handler);
+
 static inline void cpu_relax(void)
 {
 	asm volatile("nop" ::: "memory");
diff --git a/tools/testing/selftests/kvm/lib/loongarch/processor.c b/tools/testing/selftests/kvm/lib/loongarch/processor.c
index 08b4cef48e44..b2a1fa7b18da 100644
--- a/tools/testing/selftests/kvm/lib/loongarch/processor.c
+++ b/tools/testing/selftests/kvm/lib/loongarch/processor.c
@@ -11,6 +11,7 @@
 #define LOONGARCH_GUEST_STACK_VADDR_MIN		0x200000
 
 static vm_paddr_t invalid_pgtable[4];
+static vm_vaddr_t exception_handlers;
 
 static uint64_t virt_pte_index(struct kvm_vm *vm, vm_vaddr_t gva, int level)
 {
@@ -183,7 +184,14 @@ void assert_on_unhandled_exception(struct kvm_vcpu *vcpu)
 
 void route_exception(struct ex_regs *regs)
 {
+	int vector;
 	unsigned long pc, estat, badv;
+	struct handlers *handlers;
+
+	handlers = (struct handlers *)exception_handlers;
+	vector = (regs->estat & CSR_ESTAT_EXC) >> CSR_ESTAT_EXC_SHIFT;
+	if (handlers && handlers->exception_handlers[vector])
+		return handlers->exception_handlers[vector](regs);
 
 	pc = regs->pc;
 	badv  = regs->badv;
@@ -192,6 +200,27 @@ void route_exception(struct ex_regs *regs)
 	while (1) ;
 }
 
+void vm_init_descriptor_tables(struct kvm_vm *vm)
+{
+	void *addr;
+
+	vm->handlers = __vm_vaddr_alloc(vm, sizeof(struct handlers),
+			LOONGARCH_GUEST_STACK_VADDR_MIN, MEM_REGION_DATA);
+
+	addr = addr_gva2hva(vm, vm->handlers);
+	memset(addr, 0, vm->page_size);
+	exception_handlers = vm->handlers;
+	sync_global_to_guest(vm, exception_handlers);
+}
+
+void vm_install_exception_handler(struct kvm_vm *vm, int vector, handler_fn handler)
+{
+	struct handlers *handlers = addr_gva2hva(vm, vm->handlers);
+
+	assert(vector < VECTOR_NUM);
+	handlers->exception_handlers[vector] = handler;
+}
+
 uint32_t guest_get_vcpuid(void)
 {
 	return csr_read(LOONGARCH_CSR_CPUID);