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Message-Id: <20251227012712.2921408-3-lixianglai@loongson.cn> Date: Sat, 27 Dec 2025 09:27:12 +0800 From: Xianglai Li <lixianglai@...ngson.cn> To: loongarch@...ts.linux.dev, linux-kernel@...r.kernel.org, kvm@...r.kernel.org, lixianglai@...ngson.cn Cc: stable@...r.kernel.org, Huacai Chen <chenhuacai@...nel.org>, WANG Xuerui <kernel@...0n.name>, Tianrui Zhao <zhaotianrui@...ngson.cn>, Bibo Mao <maobibo@...ngson.cn>, Charlie Jenkins <charlie@...osinc.com>, Thomas Gleixner <tglx@...utronix.de>, Tiezhu Yang <yangtiezhu@...ngson.cn> Subject: [PATCH V3 2/2] LoongArch: KVM: fix "unreliable stack" issue Insert the appropriate UNWIND macro definition into the kvm_exc_entry in the assembly function to guide the generation of correct ORC table entries, thereby solving the timeout problem of loading the livepatch-sample module on a physical machine running multiple vcpus virtual machines. While solving the above problems, we have gained an additional benefit, that is, we can obtain more call stack information Stack information that can be obtained before the problem is fixed: [<0>] kvm_vcpu_block+0x88/0x120 [kvm] [<0>] kvm_vcpu_halt+0x68/0x580 [kvm] [<0>] kvm_emu_idle+0xd4/0xf0 [kvm] [<0>] kvm_handle_gspr+0x7c/0x700 [kvm] [<0>] kvm_handle_exit+0x160/0x270 [kvm] [<0>] kvm_exc_entry+0x100/0x1e0 Stack information that can be obtained after the problem is fixed: [<0>] kvm_vcpu_block+0x88/0x120 [kvm] [<0>] kvm_vcpu_halt+0x68/0x580 [kvm] [<0>] kvm_emu_idle+0xd4/0xf0 [kvm] [<0>] kvm_handle_gspr+0x7c/0x700 [kvm] [<0>] kvm_handle_exit+0x160/0x270 [kvm] [<0>] kvm_exc_entry+0x104/0x1e4 [<0>] kvm_enter_guest+0x38/0x11c [<0>] kvm_arch_vcpu_ioctl_run+0x26c/0x498 [kvm] [<0>] kvm_vcpu_ioctl+0x200/0xcf8 [kvm] [<0>] sys_ioctl+0x498/0xf00 [<0>] do_syscall+0x98/0x1d0 [<0>] handle_syscall+0xb8/0x158 Cc: stable@...r.kernel.org Signed-off-by: Xianglai Li <lixianglai@...ngson.cn> --- Cc: Huacai Chen <chenhuacai@...nel.org> Cc: WANG Xuerui <kernel@...0n.name> Cc: Tianrui Zhao <zhaotianrui@...ngson.cn> Cc: Bibo Mao <maobibo@...ngson.cn> Cc: Charlie Jenkins <charlie@...osinc.com> Cc: Xianglai Li <lixianglai@...ngson.cn> Cc: Thomas Gleixner <tglx@...utronix.de> Cc: Tiezhu Yang <yangtiezhu@...ngson.cn> arch/loongarch/kvm/switch.S | 28 +++++++++++++++++++--------- 1 file changed, 19 insertions(+), 9 deletions(-) diff --git a/arch/loongarch/kvm/switch.S b/arch/loongarch/kvm/switch.S index 93845ce53651..a3ea9567dbe5 100644 --- a/arch/loongarch/kvm/switch.S +++ b/arch/loongarch/kvm/switch.S @@ -10,6 +10,7 @@ #include <asm/loongarch.h> #include <asm/regdef.h> #include <asm/unwind_hints.h> +#include <linux/kvm_types.h> #define HGPR_OFFSET(x) (PT_R0 + 8*x) #define GGPR_OFFSET(x) (KVM_ARCH_GGPR + 8*x) @@ -110,9 +111,9 @@ * need to copy world switch code to DMW area. */ .text + .p2align PAGE_SHIFT .cfi_sections .debug_frame SYM_CODE_START(kvm_exc_entry) - .p2align PAGE_SHIFT UNWIND_HINT_UNDEFINED csrwr a2, KVM_TEMP_KS csrrd a2, KVM_VCPU_KS @@ -170,6 +171,7 @@ SYM_CODE_START(kvm_exc_entry) /* restore per cpu register */ ld.d u0, a2, KVM_ARCH_HPERCPU addi.d sp, sp, -PT_SIZE + UNWIND_HINT_REGS /* Prepare handle exception */ or a0, s0, zero @@ -200,7 +202,7 @@ ret_to_host: jr ra SYM_CODE_END(kvm_exc_entry) -EXPORT_SYMBOL(kvm_exc_entry) +EXPORT_SYMBOL_FOR_KVM(kvm_exc_entry) /* * int kvm_enter_guest(struct kvm_run *run, struct kvm_vcpu *vcpu) @@ -215,6 +217,14 @@ SYM_FUNC_START(kvm_enter_guest) /* Save host GPRs */ kvm_save_host_gpr a2 + /* + * The csr_era member variable of the pt_regs structure is required + * for unwinding orc to perform stack traceback, so we need to put + * pc into csr_era member variable here. + */ + pcaddi t0, 0 + st.d t0, a2, PT_ERA + addi.d a2, a1, KVM_VCPU_ARCH st.d sp, a2, KVM_ARCH_HSP st.d tp, a2, KVM_ARCH_HTP @@ -225,7 +235,7 @@ SYM_FUNC_START(kvm_enter_guest) csrwr a1, KVM_VCPU_KS kvm_switch_to_guest SYM_FUNC_END(kvm_enter_guest) -EXPORT_SYMBOL(kvm_enter_guest) +EXPORT_SYMBOL_FOR_KVM(kvm_enter_guest) SYM_FUNC_START(kvm_save_fpu) fpu_save_csr a0 t1 @@ -233,7 +243,7 @@ SYM_FUNC_START(kvm_save_fpu) fpu_save_cc a0 t1 t2 jr ra SYM_FUNC_END(kvm_save_fpu) -EXPORT_SYMBOL(kvm_save_fpu) +EXPORT_SYMBOL_FOR_KVM(kvm_save_fpu) SYM_FUNC_START(kvm_restore_fpu) fpu_restore_double a0 t1 @@ -241,7 +251,7 @@ SYM_FUNC_START(kvm_restore_fpu) fpu_restore_cc a0 t1 t2 jr ra SYM_FUNC_END(kvm_restore_fpu) -EXPORT_SYMBOL(kvm_restore_fpu) +EXPORT_SYMBOL_FOR_KVM(kvm_restore_fpu) #ifdef CONFIG_CPU_HAS_LSX SYM_FUNC_START(kvm_save_lsx) @@ -250,7 +260,7 @@ SYM_FUNC_START(kvm_save_lsx) lsx_save_data a0 t1 jr ra SYM_FUNC_END(kvm_save_lsx) -EXPORT_SYMBOL(kvm_save_lsx) +EXPORT_SYMBOL_FOR_KVM(kvm_save_lsx) SYM_FUNC_START(kvm_restore_lsx) lsx_restore_data a0 t1 @@ -258,7 +268,7 @@ SYM_FUNC_START(kvm_restore_lsx) fpu_restore_csr a0 t1 t2 jr ra SYM_FUNC_END(kvm_restore_lsx) -EXPORT_SYMBOL(kvm_restore_lsx) +EXPORT_SYMBOL_FOR_KVM(kvm_restore_lsx) #endif #ifdef CONFIG_CPU_HAS_LASX @@ -268,7 +278,7 @@ SYM_FUNC_START(kvm_save_lasx) lasx_save_data a0 t1 jr ra SYM_FUNC_END(kvm_save_lasx) -EXPORT_SYMBOL(kvm_save_lasx) +EXPORT_SYMBOL_FOR_KVM(kvm_save_lasx) SYM_FUNC_START(kvm_restore_lasx) lasx_restore_data a0 t1 @@ -276,7 +286,7 @@ SYM_FUNC_START(kvm_restore_lasx) fpu_restore_csr a0 t1 t2 jr ra SYM_FUNC_END(kvm_restore_lasx) -EXPORT_SYMBOL(kvm_restore_lasx) +EXPORT_SYMBOL_FOR_KVM(kvm_restore_lasx) #endif #ifdef CONFIG_CPU_HAS_LBT -- 2.39.1
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