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+0x100/0x1e0
[<0>] kvm_arch_vcpu_ioctl_run+0x260/0x488 [kvm]
[<0>] kvm_vcpu_ioctl+0x200/0xcd8 [kvm]
[<0>] sys_ioctl+0x498/0xf00
[<0>] do_syscall+0x94/0x190
[<0>] handle_syscall+0xb8/0x158
Cc: stable@vger.kernel.org
Signed-off-by: Xianglai Li <lixianglai@loongson.cn>
---
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: WANG Xuerui <kernel@xen0n.name>
Cc: Tianrui Zhao <zhaotianrui@loongson.cn>
Cc: Bibo Mao <maobibo@loongson.cn>
Cc: Charlie Jenkins <charlie@rivosinc.com>
Cc: Xianglai Li <lixianglai@loongson.cn>
Cc: Thomas Gleixner <tglx@linutronix.de>
arch/loongarch/kvm/switch.S | 2 ++
1 file changed, 2 insertions(+)
diff --git a/arch/loongarch/kvm/switch.S b/arch/loongarch/kvm/switch.S
index 93845ce53651..e3ecb24a3bc5 100644
--- a/arch/loongarch/kvm/switch.S
+++ b/arch/loongarch/kvm/switch.S
@@ -170,6 +170,7 @@ 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
@@ -214,6 +215,7 @@ SYM_FUNC_START(kvm_enter_guest)
addi.d a2, sp, -PT_SIZE
/* Save host GPRs */
kvm_save_host_gpr a2
+ st.d ra, a2, PT_ERA
addi.d a2, a1, KVM_VCPU_ARCH
st.d sp, a2, KVM_ARCH_HSP
--
2.39.1On 2025/12/22 下午7:34, Xianglai Li wrote: > 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+0x100/0x1e0 > [<0>] kvm_arch_vcpu_ioctl_run+0x260/0x488 [kvm] > [<0>] kvm_vcpu_ioctl+0x200/0xcd8 [kvm] > [<0>] sys_ioctl+0x498/0xf00 > [<0>] do_syscall+0x94/0x190 > [<0>] handle_syscall+0xb8/0x158 > > Cc: stable@vger.kernel.org > Signed-off-by: Xianglai Li <lixianglai@loongson.cn> > --- > Cc: Huacai Chen <chenhuacai@kernel.org> > Cc: WANG Xuerui <kernel@xen0n.name> > Cc: Tianrui Zhao <zhaotianrui@loongson.cn> > Cc: Bibo Mao <maobibo@loongson.cn> > Cc: Charlie Jenkins <charlie@rivosinc.com> > Cc: Xianglai Li <lixianglai@loongson.cn> > Cc: Thomas Gleixner <tglx@linutronix.de> > > arch/loongarch/kvm/switch.S | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/arch/loongarch/kvm/switch.S b/arch/loongarch/kvm/switch.S > index 93845ce53651..e3ecb24a3bc5 100644 > --- a/arch/loongarch/kvm/switch.S > +++ b/arch/loongarch/kvm/switch.S > @@ -170,6 +170,7 @@ 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 > @@ -214,6 +215,7 @@ SYM_FUNC_START(kvm_enter_guest) > addi.d a2, sp, -PT_SIZE > /* Save host GPRs */ > kvm_save_host_gpr a2 > + st.d ra, a2, PT_ERA Had better add some comments here to show that it is special for unwind usage since there is "st.d ra, a2, PT_R1" already in macro kvm_save_host_gpr(). Regards Bibo Mao > > addi.d a2, a1, KVM_VCPU_ARCH > st.d sp, a2, KVM_ARCH_HSP >
Hi Bibo Mao: > > > On 2025/12/22 下午7:34, Xianglai Li wrote: >> 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+0x100/0x1e0 >> [<0>] kvm_arch_vcpu_ioctl_run+0x260/0x488 [kvm] >> [<0>] kvm_vcpu_ioctl+0x200/0xcd8 [kvm] >> [<0>] sys_ioctl+0x498/0xf00 >> [<0>] do_syscall+0x94/0x190 >> [<0>] handle_syscall+0xb8/0x158 >> >> Cc: stable@vger.kernel.org >> Signed-off-by: Xianglai Li <lixianglai@loongson.cn> >> --- >> Cc: Huacai Chen <chenhuacai@kernel.org> >> Cc: WANG Xuerui <kernel@xen0n.name> >> Cc: Tianrui Zhao <zhaotianrui@loongson.cn> >> Cc: Bibo Mao <maobibo@loongson.cn> >> Cc: Charlie Jenkins <charlie@rivosinc.com> >> Cc: Xianglai Li <lixianglai@loongson.cn> >> Cc: Thomas Gleixner <tglx@linutronix.de> >> >> arch/loongarch/kvm/switch.S | 2 ++ >> 1 file changed, 2 insertions(+) >> >> diff --git a/arch/loongarch/kvm/switch.S b/arch/loongarch/kvm/switch.S >> index 93845ce53651..e3ecb24a3bc5 100644 >> --- a/arch/loongarch/kvm/switch.S >> +++ b/arch/loongarch/kvm/switch.S >> @@ -170,6 +170,7 @@ 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 >> @@ -214,6 +215,7 @@ SYM_FUNC_START(kvm_enter_guest) >> addi.d a2, sp, -PT_SIZE >> /* Save host GPRs */ >> kvm_save_host_gpr a2 >> + st.d ra, a2, PT_ERA > Had better add some comments here to show that it is special for > unwind usage since there is "st.d ra, a2, PT_R1" already in macro > kvm_save_host_gpr(). > Ok, I will add some comments to explain it in the next version. Thanks! Xianglai. > Regards > Bibo Mao >> addi.d a2, a1, KVM_VCPU_ARCH >> st.d sp, a2, KVM_ARCH_HSP >>
On Tue, Dec 23, 2025 at 9:27 AM Bibo Mao <maobibo@loongson.cn> wrote: > > > > On 2025/12/22 下午7:34, Xianglai Li wrote: > > 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+0x100/0x1e0 > > [<0>] kvm_arch_vcpu_ioctl_run+0x260/0x488 [kvm] > > [<0>] kvm_vcpu_ioctl+0x200/0xcd8 [kvm] > > [<0>] sys_ioctl+0x498/0xf00 > > [<0>] do_syscall+0x94/0x190 > > [<0>] handle_syscall+0xb8/0x158 > > > > Cc: stable@vger.kernel.org > > Signed-off-by: Xianglai Li <lixianglai@loongson.cn> > > --- > > Cc: Huacai Chen <chenhuacai@kernel.org> > > Cc: WANG Xuerui <kernel@xen0n.name> > > Cc: Tianrui Zhao <zhaotianrui@loongson.cn> > > Cc: Bibo Mao <maobibo@loongson.cn> > > Cc: Charlie Jenkins <charlie@rivosinc.com> > > Cc: Xianglai Li <lixianglai@loongson.cn> > > Cc: Thomas Gleixner <tglx@linutronix.de> > > > > arch/loongarch/kvm/switch.S | 2 ++ > > 1 file changed, 2 insertions(+) > > > > diff --git a/arch/loongarch/kvm/switch.S b/arch/loongarch/kvm/switch.S > > index 93845ce53651..e3ecb24a3bc5 100644 > > --- a/arch/loongarch/kvm/switch.S > > +++ b/arch/loongarch/kvm/switch.S > > @@ -170,6 +170,7 @@ 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 > > @@ -214,6 +215,7 @@ SYM_FUNC_START(kvm_enter_guest) > > addi.d a2, sp, -PT_SIZE > > /* Save host GPRs */ > > kvm_save_host_gpr a2 > > + st.d ra, a2, PT_ERA > Had better add some comments here to show that it is special for unwind > usage since there is "st.d ra, a2, PT_R1" already in macro > kvm_save_host_gpr(). Then there is a new problem, why can unwinder not recognize the instruction in kvm_save_host_gpr()? Huacai > > Regards > Bibo Mao > > > > addi.d a2, a1, KVM_VCPU_ARCH > > st.d sp, a2, KVM_ARCH_HSP > > >
On 2025/12/23 上午10:46, Huacai Chen wrote: > On Tue, Dec 23, 2025 at 9:27 AM Bibo Mao <maobibo@loongson.cn> wrote: >> >> >> >> On 2025/12/22 下午7:34, Xianglai Li wrote: >>> 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+0x100/0x1e0 >>> [<0>] kvm_arch_vcpu_ioctl_run+0x260/0x488 [kvm] >>> [<0>] kvm_vcpu_ioctl+0x200/0xcd8 [kvm] >>> [<0>] sys_ioctl+0x498/0xf00 >>> [<0>] do_syscall+0x94/0x190 >>> [<0>] handle_syscall+0xb8/0x158 >>> >>> Cc: stable@vger.kernel.org >>> Signed-off-by: Xianglai Li <lixianglai@loongson.cn> >>> --- >>> Cc: Huacai Chen <chenhuacai@kernel.org> >>> Cc: WANG Xuerui <kernel@xen0n.name> >>> Cc: Tianrui Zhao <zhaotianrui@loongson.cn> >>> Cc: Bibo Mao <maobibo@loongson.cn> >>> Cc: Charlie Jenkins <charlie@rivosinc.com> >>> Cc: Xianglai Li <lixianglai@loongson.cn> >>> Cc: Thomas Gleixner <tglx@linutronix.de> >>> >>> arch/loongarch/kvm/switch.S | 2 ++ >>> 1 file changed, 2 insertions(+) >>> >>> diff --git a/arch/loongarch/kvm/switch.S b/arch/loongarch/kvm/switch.S >>> index 93845ce53651..e3ecb24a3bc5 100644 >>> --- a/arch/loongarch/kvm/switch.S >>> +++ b/arch/loongarch/kvm/switch.S >>> @@ -170,6 +170,7 @@ 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 >>> @@ -214,6 +215,7 @@ SYM_FUNC_START(kvm_enter_guest) >>> addi.d a2, sp, -PT_SIZE >>> /* Save host GPRs */ >>> kvm_save_host_gpr a2 >>> + st.d ra, a2, PT_ERA >> Had better add some comments here to show that it is special for unwind >> usage since there is "st.d ra, a2, PT_R1" already in macro >> kvm_save_host_gpr(). > Then there is a new problem, why can unwinder not recognize the > instruction in kvm_save_host_gpr()? maybe it need unwinder owner to answer this question. > > Huacai >> >> Regards >> Bibo Mao >>> >>> addi.d a2, a1, KVM_VCPU_ARCH >>> st.d sp, a2, KVM_ARCH_HSP >>> >>
Add yangtiezhu@loongson.cn Hi : > > > On 2025/12/23 上午10:46, Huacai Chen wrote: >> On Tue, Dec 23, 2025 at 9:27 AM Bibo Mao <maobibo@loongson.cn> wrote: >>> >>> >>> >>> On 2025/12/22 下午7:34, Xianglai Li wrote: >>>> 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+0x100/0x1e0 >>>> [<0>] kvm_arch_vcpu_ioctl_run+0x260/0x488 [kvm] >>>> [<0>] kvm_vcpu_ioctl+0x200/0xcd8 [kvm] >>>> [<0>] sys_ioctl+0x498/0xf00 >>>> [<0>] do_syscall+0x94/0x190 >>>> [<0>] handle_syscall+0xb8/0x158 >>>> >>>> Cc: stable@vger.kernel.org >>>> Signed-off-by: Xianglai Li <lixianglai@loongson.cn> >>>> --- >>>> Cc: Huacai Chen <chenhuacai@kernel.org> >>>> Cc: WANG Xuerui <kernel@xen0n.name> >>>> Cc: Tianrui Zhao <zhaotianrui@loongson.cn> >>>> Cc: Bibo Mao <maobibo@loongson.cn> >>>> Cc: Charlie Jenkins <charlie@rivosinc.com> >>>> Cc: Xianglai Li <lixianglai@loongson.cn> >>>> Cc: Thomas Gleixner <tglx@linutronix.de> >>>> >>>> arch/loongarch/kvm/switch.S | 2 ++ >>>> 1 file changed, 2 insertions(+) >>>> >>>> diff --git a/arch/loongarch/kvm/switch.S b/arch/loongarch/kvm/switch.S >>>> index 93845ce53651..e3ecb24a3bc5 100644 >>>> --- a/arch/loongarch/kvm/switch.S >>>> +++ b/arch/loongarch/kvm/switch.S >>>> @@ -170,6 +170,7 @@ 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 >>>> @@ -214,6 +215,7 @@ SYM_FUNC_START(kvm_enter_guest) >>>> addi.d a2, sp, -PT_SIZE >>>> /* Save host GPRs */ >>>> kvm_save_host_gpr a2 >>>> + st.d ra, a2, PT_ERA >>> Had better add some comments here to show that it is special for unwind >>> usage since there is "st.d ra, a2, PT_R1" already in macro >>> kvm_save_host_gpr(). >> Then there is a new problem, why can unwinder not recognize the >> instruction in kvm_save_host_gpr()? > maybe it need unwinder owner to answer this question. > kvm_save_host_gpr() is an assembler macro that has already been executed and is no longer normal on the stack. Am I explaining correctly? @tiezhu I guess you might be wondering why unwinder didn't recognize kvm_enter_guest(). There's something wrong with the logic that we're implementing here that we should put the current pc in era instead of ra. This will allow unwind to identify the symbol kvm_enter_guest. So I will fix it in the next version like this: @@ -214,6 +215,7 @@ SYM_FUNC_START(kvm_enter_guest) addi.d a2, sp, -PT_SIZE /* 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 + Thanks, Xianglai. >> >> Huacai >>> >>> Regards >>> Bibo Mao >>>> >>>> addi.d a2, a1, KVM_VCPU_ARCH >>>> st.d sp, a2, KVM_ARCH_HSP >>>> >>>
Hi: > Add yangtiezhu@loongson.cn > > Hi : >> >> >> On 2025/12/23 上午10:46, Huacai Chen wrote: >>> On Tue, Dec 23, 2025 at 9:27 AM Bibo Mao <maobibo@loongson.cn> wrote: >>>> >>>> >>>> >>>> On 2025/12/22 下午7:34, Xianglai Li wrote: >>>>> 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+0x100/0x1e0 >>>>> [<0>] kvm_arch_vcpu_ioctl_run+0x260/0x488 [kvm] >>>>> [<0>] kvm_vcpu_ioctl+0x200/0xcd8 [kvm] >>>>> [<0>] sys_ioctl+0x498/0xf00 >>>>> [<0>] do_syscall+0x94/0x190 >>>>> [<0>] handle_syscall+0xb8/0x158 >>>>> >>>>> Cc: stable@vger.kernel.org >>>>> Signed-off-by: Xianglai Li <lixianglai@loongson.cn> >>>>> --- >>>>> Cc: Huacai Chen <chenhuacai@kernel.org> >>>>> Cc: WANG Xuerui <kernel@xen0n.name> >>>>> Cc: Tianrui Zhao <zhaotianrui@loongson.cn> >>>>> Cc: Bibo Mao <maobibo@loongson.cn> >>>>> Cc: Charlie Jenkins <charlie@rivosinc.com> >>>>> Cc: Xianglai Li <lixianglai@loongson.cn> >>>>> Cc: Thomas Gleixner <tglx@linutronix.de> >>>>> >>>>> arch/loongarch/kvm/switch.S | 2 ++ >>>>> 1 file changed, 2 insertions(+) >>>>> >>>>> diff --git a/arch/loongarch/kvm/switch.S >>>>> b/arch/loongarch/kvm/switch.S >>>>> index 93845ce53651..e3ecb24a3bc5 100644 >>>>> --- a/arch/loongarch/kvm/switch.S >>>>> +++ b/arch/loongarch/kvm/switch.S >>>>> @@ -170,6 +170,7 @@ 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 >>>>> @@ -214,6 +215,7 @@ SYM_FUNC_START(kvm_enter_guest) >>>>> addi.d a2, sp, -PT_SIZE >>>>> /* Save host GPRs */ >>>>> kvm_save_host_gpr a2 >>>>> + st.d ra, a2, PT_ERA >>>> Had better add some comments here to show that it is special for >>>> unwind >>>> usage since there is "st.d ra, a2, PT_R1" already in macro >>>> kvm_save_host_gpr(). >>> Then there is a new problem, why can unwinder not recognize the >>> instruction in kvm_save_host_gpr()? >> maybe it need unwinder owner to answer this question. >> > kvm_save_host_gpr() is an assembler macro that has already been > executed and is no longer normal on the stack. > Am I explaining correctly? @tiezhu > > I guess you might be wondering why unwinder didn't recognize > kvm_enter_guest(). > > There's something wrong with the logic that we're implementing here > that we should put the current pc in era instead of ra. > This will allow unwind to identify the symbol kvm_enter_guest. > > So I will fix it in the next version like this: > > @@ -214,6 +215,7 @@ SYM_FUNC_START(kvm_enter_guest) > addi.d a2, sp, -PT_SIZE > /* 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 > + > We discussed it with @tiezhu internally and he was OK with the change! Thanks, Xianglai. > Thanks, > Xianglai. >>> >>> Huacai >>>> >>>> Regards >>>> Bibo Mao >>>>> >>>>> addi.d a2, a1, KVM_VCPU_ARCH >>>>> st.d sp, a2, KVM_ARCH_HSP >>>>> >>>> >
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