linux-kernel - [PATCH 2/6] KVM: LoongArch: selftests: Add exception handler register interface

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Message-Id: <20251031031227.4020738-3-maobibo@loongson.cn>
Date: Fri, 31 Oct 2025 11:12:23 +0800
From: Bibo Mao <maobibo@...ngson.cn>
To: Paolo Bonzini <pbonzini@...hat.com>,
	Sean Christopherson <seanjc@...gle.com>,
	Shuah Khan <shuah@...nel.org>,
	Tianrui Zhao <zhaotianrui@...ngson.cn>,
	Huacai Chen <chenhuacai@...nel.org>,
	Paul Walmsley <pjw@...nel.org>,
	Palmer Dabbelt <palmer@...belt.com>,
	Albert Ou <aou@...s.berkeley.edu>,
	Alexandre Ghiti <alex@...ti.fr>
Cc: linux-kernel@...r.kernel.org,
	kvm@...r.kernel.org,
	linux-kselftest@...r.kernel.org,
	loongarch@...ts.linux.dev,
	linux-riscv@...ts.infradead.org
Subject: [PATCH 2/6] 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
error.

Signed-off-by: Bibo Mao <maobibo@...ngson.cn>
---
 .../kvm/include/loongarch/processor.h         | 14 +++++++++
 .../selftests/kvm/lib/loongarch/processor.c   | 29 +++++++++++++++++++
 2 files changed, 43 insertions(+)

diff --git a/tools/testing/selftests/kvm/include/loongarch/processor.h b/tools/testing/selftests/kvm/include/loongarch/processor.h
index 374caddfb0db..a18ac7bff303 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
@@ -133,6 +138,15 @@ 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);
+
 #else
 #define PC_OFFSET_EXREGS		((EXREGS_GPRS + 0) * 8)
 #define ESTAT_OFFSET_EXREGS		((EXREGS_GPRS + 1) * 8)
diff --git a/tools/testing/selftests/kvm/lib/loongarch/processor.c b/tools/testing/selftests/kvm/lib/loongarch/processor.c
index 0ac1abcb71cb..be537c5ff74e 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)
 {
@@ -184,6 +185,13 @@ void assert_on_unhandled_exception(struct kvm_vcpu *vcpu)
 void route_exception(struct ex_regs *regs)
 {
 	unsigned long pc, estat, badv;
+	int vector;
+	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;
+}
+
 void vcpu_args_set(struct kvm_vcpu *vcpu, unsigned int num, ...)
 {
 	int i;
-- 
2.39.3