by Huacai Chen

[permalink] [raw]

Subject: Re: [PATCH v8 4/6] LoongArch: KVM: Add vcpu search support from physical cpuid

On Tue, May 7, 2024 at 11:06 AM maobibo <[email protected]> wrote:
>
>
>
> On 2024/5/7 上午10:05, Huacai Chen wrote:
> > On Tue, May 7, 2024 at 9:40 AM maobibo <[email protected]> wrote:
> >>
> >>
> >>
> >> On 2024/5/6 下午10:17, Huacai Chen wrote:
> >>> On Mon, May 6, 2024 at 6:05 PM maobibo <[email protected]> wrote:
> >>>>
> >>>>
> >>>>
> >>>> On 2024/5/6 下午5:40, Huacai Chen wrote:
> >>>>> On Mon, May 6, 2024 at 5:35 PM maobibo <[email protected]> wrote:
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>>> On 2024/5/6 下午4:59, Huacai Chen wrote:
> >>>>>>> On Mon, May 6, 2024 at 4:18 PM maobibo <[email protected]> wrote:
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>> On 2024/5/6 下午3:06, Huacai Chen wrote:
> >>>>>>>>> Hi, Bibo,
> >>>>>>>>>
> >>>>>>>>> On Mon, May 6, 2024 at 2:36 PM maobibo <[email protected]> wrote:
> >>>>>>>>>>
> >>>>>>>>>>
> >>>>>>>>>>
> >>>>>>>>>> On 2024/5/6 上午9:49, Huacai Chen wrote:
> >>>>>>>>>>> Hi, Bibo,
> >>>>>>>>>>>
> >>>>>>>>>>> On Sun, Apr 28, 2024 at 6:05 PM Bibo Mao <[email protected]> wrote:
> >>>>>>>>>>>>
> >>>>>>>>>>>> Physical cpuid is used for interrupt routing for irqchips such as
> >>>>>>>>>>>> ipi/msi/extioi interrupt controller. And physical cpuid is stored
> >>>>>>>>>>>> at CSR register LOONGARCH_CSR_CPUID, it can not be changed once vcpu
> >>>>>>>>>>>> is created and physical cpuid of two vcpus cannot be the same.
> >>>>>>>>>>>>
> >>>>>>>>>>>> Different irqchips have different size declaration about physical cpuid,
> >>>>>>>>>>>> max cpuid value for CSR LOONGARCH_CSR_CPUID on 3A5000 is 512, max cpuid
> >>>>>>>>>>>> supported by IPI hardware is 1024, 256 for extioi irqchip, and 65536
> >>>>>>>>>>>> for MSI irqchip.
> >>>>>>>>>>>>
> >>>>>>>>>>>> The smallest value from all interrupt controllers is selected now,
> >>>>>>>>>>>> and the max cpuid size is defines as 256 by KVM which comes from
> >>>>>>>>>>>> extioi irqchip.
> >>>>>>>>>>>>
> >>>>>>>>>>>> Signed-off-by: Bibo Mao <[email protected]>
> >>>>>>>>>>>> ---
> >>>>>>>>>>>> arch/loongarch/include/asm/kvm_host.h | 26 ++++++++
> >>>>>>>>>>>> arch/loongarch/include/asm/kvm_vcpu.h | 1 +
> >>>>>>>>>>>> arch/loongarch/kvm/vcpu.c | 93 ++++++++++++++++++++++++++-
> >>>>>>>>>>>> arch/loongarch/kvm/vm.c | 11 ++++
> >>>>>>>>>>>> 4 files changed, 130 insertions(+), 1 deletion(-)
> >>>>>>>>>>>>
> >>>>>>>>>>>> diff --git a/arch/loongarch/include/asm/kvm_host.h b/arch/loongarch/include/asm/kvm_host.h
> >>>>>>>>>>>> index 2d62f7b0d377..3ba16ef1fe69 100644
> >>>>>>>>>>>> --- a/arch/loongarch/include/asm/kvm_host.h
> >>>>>>>>>>>> +++ b/arch/loongarch/include/asm/kvm_host.h
> >>>>>>>>>>>> @@ -64,6 +64,30 @@ struct kvm_world_switch {
> >>>>>>>>>>>>
> >>>>>>>>>>>> #define MAX_PGTABLE_LEVELS 4
> >>>>>>>>>>>>
> >>>>>>>>>>>> +/*
> >>>>>>>>>>>> + * Physical cpu id is used for interrupt routing, there are different
> >>>>>>>>>>>> + * definitions about physical cpuid on different hardwares.
> >>>>>>>>>>>> + * For LOONGARCH_CSR_CPUID register, max cpuid size if 512
> >>>>>>>>>>>> + * For IPI HW, max dest CPUID size 1024
> >>>>>>>>>>>> + * For extioi interrupt controller, max dest CPUID size is 256
> >>>>>>>>>>>> + * For MSI interrupt controller, max supported CPUID size is 65536
> >>>>>>>>>>>> + *
> >>>>>>>>>>>> + * Currently max CPUID is defined as 256 for KVM hypervisor, in future
> >>>>>>>>>>>> + * it will be expanded to 4096, including 16 packages at most. And every
> >>>>>>>>>>>> + * package supports at most 256 vcpus
> >>>>>>>>>>>> + */
> >>>>>>>>>>>> +#define KVM_MAX_PHYID 256
> >>>>>>>>>>>> +
> >>>>>>>>>>>> +struct kvm_phyid_info {
> >>>>>>>>>>>> + struct kvm_vcpu *vcpu;
> >>>>>>>>>>>> + bool enabled;
> >>>>>>>>>>>> +};
> >>>>>>>>>>>> +
> >>>>>>>>>>>> +struct kvm_phyid_map {
> >>>>>>>>>>>> + int max_phyid;
> >>>>>>>>>>>> + struct kvm_phyid_info phys_map[KVM_MAX_PHYID];
> >>>>>>>>>>>> +};
> >>>>>>>>>>>> +
> >>>>>>>>>>>> struct kvm_arch {
> >>>>>>>>>>>> /* Guest physical mm */
> >>>>>>>>>>>> kvm_pte_t *pgd;
> >>>>>>>>>>>> @@ -71,6 +95,8 @@ struct kvm_arch {
> >>>>>>>>>>>> unsigned long invalid_ptes[MAX_PGTABLE_LEVELS];
> >>>>>>>>>>>> unsigned int pte_shifts[MAX_PGTABLE_LEVELS];
> >>>>>>>>>>>> unsigned int root_level;
> >>>>>>>>>>>> + spinlock_t phyid_map_lock;
> >>>>>>>>>>>> + struct kvm_phyid_map *phyid_map;
> >>>>>>>>>>>>
> >>>>>>>>>>>> s64 time_offset;
> >>>>>>>>>>>> struct kvm_context __percpu *vmcs;
> >>>>>>>>>>>> diff --git a/arch/loongarch/include/asm/kvm_vcpu.h b/arch/loongarch/include/asm/kvm_vcpu.h
> >>>>>>>>>>>> index 0cb4fdb8a9b5..9f53950959da 100644
> >>>>>>>>>>>> --- a/arch/loongarch/include/asm/kvm_vcpu.h
> >>>>>>>>>>>> +++ b/arch/loongarch/include/asm/kvm_vcpu.h
> >>>>>>>>>>>> @@ -81,6 +81,7 @@ void kvm_save_timer(struct kvm_vcpu *vcpu);
> >>>>>>>>>>>> void kvm_restore_timer(struct kvm_vcpu *vcpu);
> >>>>>>>>>>>>
> >>>>>>>>>>>> int kvm_vcpu_ioctl_interrupt(struct kvm_vcpu *vcpu, struct kvm_interrupt *irq);
> >>>>>>>>>>>> +struct kvm_vcpu *kvm_get_vcpu_by_cpuid(struct kvm *kvm, int cpuid);
> >>>>>>>>>>>>
> >>>>>>>>>>>> /*
> >>>>>>>>>>>> * Loongarch KVM guest interrupt handling
> >>>>>>>>>>>> diff --git a/arch/loongarch/kvm/vcpu.c b/arch/loongarch/kvm/vcpu.c
> >>>>>>>>>>>> index 3a8779065f73..b633fd28b8db 100644
> >>>>>>>>>>>> --- a/arch/loongarch/kvm/vcpu.c
> >>>>>>>>>>>> +++ b/arch/loongarch/kvm/vcpu.c
> >>>>>>>>>>>> @@ -274,6 +274,95 @@ static int _kvm_getcsr(struct kvm_vcpu *vcpu, unsigned int id, u64 *val)
> >>>>>>>>>>>> return 0;
> >>>>>>>>>>>> }
> >>>>>>>>>>>>
> >>>>>>>>>>>> +static inline int kvm_set_cpuid(struct kvm_vcpu *vcpu, u64 val)
> >>>>>>>>>>>> +{
> >>>>>>>>>>>> + int cpuid;
> >>>>>>>>>>>> + struct loongarch_csrs *csr = vcpu->arch.csr;
> >>>>>>>>>>>> + struct kvm_phyid_map *map;
> >>>>>>>>>>>> +
> >>>>>>>>>>>> + if (val >= KVM_MAX_PHYID)
> >>>>>>>>>>>> + return -EINVAL;
> >>>>>>>>>>>> +
> >>>>>>>>>>>> + cpuid = kvm_read_sw_gcsr(csr, LOONGARCH_CSR_ESTAT);
> >>>>>>>>>>>> + map = vcpu->kvm->arch.phyid_map;
> >>>>>>>>>>>> + spin_lock(&vcpu->kvm->arch.phyid_map_lock);
> >>>>>>>>>>>> + if (map->phys_map[cpuid].enabled) {
> >>>>>>>>>>>> + /*
> >>>>>>>>>>>> + * Cpuid is already set before
> >>>>>>>>>>>> + * Forbid changing different cpuid at runtime
> >>>>>>>>>>>> + */
> >>>>>>>>>>>> + if (cpuid != val) {
> >>>>>>>>>>>> + /*
> >>>>>>>>>>>> + * Cpuid 0 is initial value for vcpu, maybe invalid
> >>>>>>>>>>>> + * unset value for vcpu
> >>>>>>>>>>>> + */
> >>>>>>>>>>>> + if (cpuid) {
> >>>>>>>>>>>> + spin_unlock(&vcpu->kvm->archphyid_map_lock);
> >>>>>>>>>>>> + return -EINVAL;
> >>>>>>>>>>>> + }
> >>>>>>>>>>>> + } else {
> >>>>>>>>>>>> + /* Discard duplicated cpuid set */
> >>>>>>>>>>>> + spin_unlock(&vcpu->kvm->arch.phyid_map_lock);
> >>>>>>>>>>>> + return 0;
> >>>>>>>>>>>> + }
> >>>>>>>>>>>> + }
> >>>>>>>>>>> I have changed the logic and comments when I apply, you can double
> >>>>>>>>>>> check whether it is correct.
> >>>>>>>>>> I checkout the latest version, the modification in function
> >>>>>>>>>> kvm_set_cpuid() is good for me.
> >>>>>>>>> Now the modified version is like this:
> >>>>>>>>>
> >>>>>>>>> + if (map->phys_map[cpuid].enabled) {
> >>>>>>>>> + /* Discard duplicated CPUID set operation */
> >>>>>>>>> + if (cpuid == val) {
> >>>>>>>>> + spin_unlock(&vcpu->kvm->arch.phyid_map_lock);
> >>>>>>>>> + return 0;
> >>>>>>>>> + }
> >>>>>>>>> +
> >>>>>>>>> + /*
> >>>>>>>>> + * CPUID is already set before
> >>>>>>>>> + * Forbid changing different CPUID at runtime
> >>>>>>>>> + * But CPUID 0 is the initial value for vcpu, so allow
> >>>>>>>>> + * changing from 0 to others
> >>>>>>>>> + */
> >>>>>>>>> + if (cpuid) {
> >>>>>>>>> + spin_unlock(&vcpu->kvm->arch.phyid_map_lock);
> >>>>>>>>> + return -EINVAL;
> >>>>>>>>> + }
> >>>>>>>>> + }
> >>>>>>>>> But I still doubt whether we should allow changing from 0 to others
> >>>>>>>>> while map->phys_map[cpuid].enabled is 1.
> >>>>>>>> It is necessary since the default sw cpuid is zero :-( And we can
> >>>>>>>> optimize it in later, such as set INVALID cpuid in function
> >>>>>>>> kvm_arch_vcpu_create() and logic will be simple in function kvm_set_cpuid().
> >>>>>>> In my opinion, if a vcpu with a uninitialized default physid=0, then
> >>>>>>> map->phys_map[cpuid].enabled should be 0, then code won't come here.
> >>>>>>> And if a vcpu with a real physid=0, then map->phys_map[cpuid].enabled
> >>>>>>> is 1, but we shouldn't allow it to change physid in this case.
> >>>>>> yes, that is actually a problem.
> >>>>>>
> >>>>>> vcpu0 firstly set physid=0, and vcpu0 set physid=1 again is not allowed.
> >>>>>> vcpu0 firstly set physid=0, and vcpu1 set physid=1 is allowed.
> >>>>>
> >>>>> So can we simply drop the if (cpuid) checking? That means:
> >>>>> + if (map->phys_map[cpuid].enabled) {
> >>>>> + /* Discard duplicated CPUID set operation */
> >>>>> + if (cpuid == val) {
> >>>>> + spin_unlock(&vcpu->kvm->arch.phyid_map_lock);
> >>>>> + return 0;
> >>>>> + }
> >>>>> +
> >>>>> + spin_unlock(&vcpu->kvm->arch.phyid_map_lock);
> >>>>> + return -EINVAL;
> >>>>> + }
> >>>> yes, the similar modification such as following, since the secondary
> >>>> scenario should be allowed.
> >>>> "vcpu0 firstly set physid=0, and vcpu1 set physid=1 is allowed though
> >>>> default sw cpuid is zero"
> >>>>
> >>>> --- a/arch/loongarch/kvm/vcpu.c
> >>>> +++ b/arch/loongarch/kvm/vcpu.c
> >>>> @@ -272,7 +272,7 @@ static inline int kvm_set_cpuid(struct kvm_vcpu
> >>>> *vcpu, u64 val)
> >>>> cpuid = kvm_read_sw_gcsr(csr, LOONGARCH_CSR_CPUID);
> >>>>
> >>>> spin_lock(&vcpu->kvm->arch.phyid_map_lock);
> >>>> - if (map->phys_map[cpuid].enabled) {
> >>>> + if ((cpuid != KVM_MAX_PHYID) && map->phys_map[cpuid].enabled) {
> >>>> /* Discard duplicated CPUID set operation */
> >>>> if (cpuid == val) {
> >>>> spin_unlock(&vcpu->kvm->arch.phyid_map_lock);
> >>>> @@ -282,13 +282,9 @@ static inline int kvm_set_cpuid(struct kvm_vcpu
> >>>> *vcpu, u64 val)
> >>>> /*
> >>>> * CPUID is already set before
> >>>> * Forbid changing different CPUID at runtime
> >>>> - * But CPUID 0 is the initial value for vcpu, so allow
> >>>> - * changing from 0 to others
> >>>> */
> >>>> - if (cpuid) {
> >>>> - spin_unlock(&vcpu->kvm->arch.phyid_map_lock);
> >>>> - return -EINVAL;
> >>>> - }
> >>>> + spin_unlock(&vcpu->kvm->arch.phyid_map_lock);
> >>>> + return -EINVAL;
> >>>> }
> >>>>
> >>>> if (map->phys_map[val].enabled) {
> >>>> @@ -1029,6 +1025,7 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
> >>>>
> >>>> /* Set cpuid */
> >>>> kvm_write_sw_gcsr(csr, LOONGARCH_CSR_TMID, vcpu->vcpu_id);
> >>>> + kvm_write_sw_gcsr(csr, LOONGARCH_CSR_CPUID, KVM_MAX_PHYID);
> >>>>
> >>>> /* Start with no pending virtual guest interrupts */
> >>>> csr->csrs[LOONGARCH_CSR_GINTC] = 0;
> >>> Very nice, but I think kvm_drop_cpuid() should also set to KVM_MAX_PHYID.
> >>> Now I update my loongarch-kvm branch, you can test it again, and hope
> >>> it is in the perfect status.
> >> I sync and test the latest code from loongarch-kvm, pv ipi works well
> >> with 256 vcpus. And the code looks good to me, thanks for your review in
> >> short time.
> > OK, if SWDBG also works well, I will send PR to Paolo tomorrow.
> yes, sw debug works well with patch from qemu. And I will refresh patch
> to qemu after it is merged.
>
> https://lore.kernel.org/all/[email protected]/
>
> --- a/configs/targets/loongarch64-softmmu.mak
> +++ b/configs/targets/loongarch64-softmmu.mak
> @@ -1,5 +1,6 @@
> TARGET_ARCH=loongarch64
> TARGET_BASE_ARCH=loongarch
> TARGET_SUPPORTS_MTTCG=y
> +TARGET_KVM_HAVE_GUEST_DEBUG=y
> TARGET_XML_FILES= gdb-xml/loongarch-base32.xml
> gdb-xml/loongarch-base64.xml gdb-xml/loongarch-fpu.xml
> TARGET_NEED_FDT=y
Not enough, we need kvm_arch_update_guest_debug() and some other functions.

Huacai

>
> Regards
> Bibo Mao
> >
> > Huacai
> >
> >>
> >> Regards
> >> Bibo Mao
> >>>
> >>> Huacai
> >>>>
> >>>>
> >>>>>
> >>>>> Huacai
> >>>>>
> >>>>>>
> >>>>>>
> >>>>>>>
> >>>>>>> Huacai
> >>>>>>>
> >>>>>>>>
> >>>>>>>> Regards
> >>>>>>>> Bibo Mao
> >>>>>>>>
> >>>>>>>>>
> >>>>>>>>> Huacai
> >>>>>>>>>
> >>>>>>>>>>>
> >>>>>>>>>>>> +
> >>>>>>>>>>>> + if (map->phys_map[val].enabled) {
> >>>>>>>>>>>> + /*
> >>>>>>>>>>>> + * New cpuid is already set with other vcpu
> >>>>>>>>>>>> + * Forbid sharing the same cpuid between different vcpus
> >>>>>>>>>>>> + */
> >>>>>>>>>>>> + if (map->phys_map[val].vcpu != vcpu) {
> >>>>>>>>>>>> + spin_unlock(&vcpu->kvm->arch.phyid_map_lock);
> >>>>>>>>>>>> + return -EINVAL;
> >>>>>>>>>>>> + }
> >>>>>>>>>>>> +
> >>>>>>>>>>>> + /* Discard duplicated cpuid set operation*/
> >>>>>>>>>>>> + spin_unlock(&vcpu->kvm->arch.phyid_map_lock);
> >>>>>>>>>>>> + return 0;
> >>>>>>>>>>>> + }
> >>>>>>>>>>>> +
> >>>>>>>>>>>> + kvm_write_sw_gcsr(csr, LOONGARCH_CSR_CPUID, val);
> >>>>>>>>>>>> + map->phys_map[val].enabled = true;
> >>>>>>>>>>>> + map->phys_map[val].vcpu = vcpu;
> >>>>>>>>>>>> + if (map->max_phyid < val)
> >>>>>>>>>>>> + map->max_phyid = val;
> >>>>>>>>>>>> + spin_unlock(&vcpu->kvm->arch.phyid_map_lock);
> >>>>>>>>>>>> + return 0;
> >>>>>>>>>>>> +}
> >>>>>>>>>>>> +
> >>>>>>>>>>>> +struct kvm_vcpu *kvm_get_vcpu_by_cpuid(struct kvm *kvm, int cpuid)
> >>>>>>>>>>>> +{
> >>>>>>>>>>>> + struct kvm_phyid_map *map;
> >>>>>>>>>>>> +
> >>>>>>>>>>>> + if (cpuid >= KVM_MAX_PHYID)
> >>>>>>>>>>>> + return NULL;
> >>>>>>>>>>>> +
> >>>>>>>>>>>> + map = kvm->arch.phyid_map;
> >>>>>>>>>>>> + if (map->phys_map[cpuid].enabled)
> >>>>>>>>>>>> + return map->phys_map[cpuid].vcpu;
> >>>>>>>>>>>> +
> >>>>>>>>>>>> + return NULL;
> >>>>>>>>>>>> +}
> >>>>>>>>>>>> +
> >>>>>>>>>>>> +static inline void kvm_drop_cpuid(struct kvm_vcpu *vcpu)
> >>>>>>>>>>>> +{
> >>>>>>>>>>>> + int cpuid;
> >>>>>>>>>>>> + struct loongarch_csrs *csr = vcpu->arch.csr;
> >>>>>>>>>>>> + struct kvm_phyid_map *map;
> >>>>>>>>>>>> +
> >>>>>>>>>>>> + map = vcpu->kvm->arch.phyid_map;
> >>>>>>>>>>>> + cpuid = kvm_read_sw_gcsr(csr, LOONGARCH_CSR_ESTAT);
> >>>>>>>>>>>> + if (cpuid >= KVM_MAX_PHYID)
> >>>>>>>>>>>> + return;
> >>>>>>>>>>>> +
> >>>>>>>>>>>> + if (map->phys_map[cpuid].enabled) {
> >>>>>>>>>>>> + map->phys_map[cpuid].vcpu = NULL;
> >>>>>>>>>>>> + map->phys_map[cpuid].enabled = false;
> >>>>>>>>>>>> + kvm_write_sw_gcsr(csr, LOONGARCH_CSR_CPUID, 0);
> >>>>>>>>>>>> + }
> >>>>>>>>>>>> +}
> >>>>>>>>>>> While kvm_set_cpuid() is protected by a spinlock, do kvm_drop_cpuid()
> >>>>>>>>>>> and kvm_get_vcpu_by_cpuid() also need it?
> >>>>>>>>>>>
> >>>>>>>>>> It is good to me that spinlock is added in function kvm_drop_cpuid().
> >>>>>>>>>> And thinks for the efforts.
> >>>>>>>>>>
> >>>>>>>>>> Regards
> >>>>>>>>>> Bibo Mao
> >>>>>>>>>>>> +
> >>>>>>>>>>>> static int _kvm_setcsr(struct kvm_vcpu *vcpu, unsigned int id, u64 val)
> >>>>>>>>>>>> {
> >>>>>>>>>>>> int ret = 0, gintc;
> >>>>>>>>>>>> @@ -291,7 +380,8 @@ static int _kvm_setcsr(struct kvm_vcpu *vcpu, unsigned int id, u64 val)
> >>>>>>>>>>>> kvm_set_sw_gcsr(csr, LOONGARCH_CSR_ESTAT, gintc);
> >>>>>>>>>>>>
> >>>>>>>>>>>> return ret;
> >>>>>>>>>>>> - }
> >>>>>>>>>>>> + } else if (id == LOONGARCH_CSR_CPUID)
> >>>>>>>>>>>> + return kvm_set_cpuid(vcpu, val);
> >>>>>>>>>>>>
> >>>>>>>>>>>> kvm_write_sw_gcsr(csr, id, val);
> >>>>>>>>>>>>
> >>>>>>>>>>>> @@ -943,6 +1033,7 @@ void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu)
> >>>>>>>>>>>> hrtimer_cancel(&vcpu->arch.swtimer);
> >>>>>>>>>>>> kvm_mmu_free_memory_cache(&vcpu->arch.mmu_page_cache);
> >>>>>>>>>>>> kfree(vcpu->arch.csr);
> >>>>>>>>>>>> + kvm_drop_cpuid(vcpu);
> >>>>>>>>>>> I think this line should be before the above kfree(), otherwise you
> >>>>>>>>>>> get a "use after free".
> >>>>>>>>>>>
> >>>>>>>>>>> Huacai
> >>>>>>>>>>>
> >>>>>>>>>>>>
> >>>>>>>>>>>> /*
> >>>>>>>>>>>> * If the vCPU is freed and reused as another vCPU, we don't want the
> >>>>>>>>>>>> diff --git a/arch/loongarch/kvm/vm.c b/arch/loongarch/kvm/vmc
> >>>>>>>>>>>> index 0a37f6fa8f2d..6006a28653ad 100644
> >>>>>>>>>>>> --- a/arch/loongarch/kvm/vm.c
> >>>>>>>>>>>> +++ b/arch/loongarch/kvm/vm.c
> >>>>>>>>>>>> @@ -30,6 +30,14 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
> >>>>>>>>>>>> if (!kvm->arch.pgd)
> >>>>>>>>>>>> return -ENOMEM;
> >>>>>>>>>>>>
> >>>>>>>>>>>> + kvm->arch.phyid_map = kvzalloc(sizeof(struct kvm_phyid_map),
> >>>>>>>>>>>> + GFP_KERNEL_ACCOUNT);
> >>>>>>>>>>>> + if (!kvm->arch.phyid_map) {
> >>>>>>>>>>>> + free_page((unsigned long)kvm->arch.pgd);
> >>>>>>>>>>>> + kvm->arch.pgd = NULL;
> >>>>>>>>>>>> + return -ENOMEM;
> >>>>>>>>>>>> + }
> >>>>>>>>>>>> +
> >>>>>>>>>>>> kvm_init_vmcs(kvm);
> >>>>>>>>>>>> kvm->arch.gpa_size = BIT(cpu_vabits - 1);
> >>>>>>>>>>>> kvm->arch.root_level = CONFIG_PGTABLE_LEVELS - 1;
> >>>>>>>>>>>> @@ -44,6 +52,7 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
> >>>>>>>>>>>> for (i = 0; i <= kvm->arch.root_level; i++)
> >>>>>>>>>>>> kvm->arch.pte_shifts[i] = PAGE_SHIFT + i * (PAGE_SHIFT - 3);
> >>>>>>>>>>>>
> >>>>>>>>>>>> + spin_lock_init(&kvm->arch.phyid_map_lock);
> >>>>>>>>>>>> return 0;
> >>>>>>>>>>>> }
> >>>>>>>>>>>>
> >>>>>>>>>>>> @@ -51,7 +60,9 @@ void kvm_arch_destroy_vm(struct kvm *kvm)
> >>>>>>>>>>>> {
> >>>>>>>>>>>> kvm_destroy_vcpus(kvm);
> >>>>>>>>>>>> free_page((unsigned long)kvm->arch.pgd);
> >>>>>>>>>>>> + kvfree(kvm->arch.phyid_map);
> >>>>>>>>>>>> kvm->arch.pgd = NULL;
> >>>>>>>>>>>> + kvm->arch.phyid_map = NULL;
> >>>>>>>>>>>> }
> >>>>>>>>>>>>
> >>>>>>>>>>>> int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
> >>>>>>>>>>>> --
> >>>>>>>>>>>> 2.39.3
> >>>>>>>>>>>>
> >>>>>>>>>>
> >>>>>>>>
> >>>>>>
> >>>>
> >>
> >>
>
>

2024-05-08 06:10:46

by Bibo Mao

[permalink] [raw]

Subject: Re: [PATCH v8 4/6] LoongArch: KVM: Add vcpu search support from physical cpuid

On 2024/5/8 下午1:00, Huacai Chen wrote:
> On Tue, May 7, 2024 at 11:06 AM maobibo <[email protected]> wrote:
>>
>>
>>
>> On 2024/5/7 上午10:05, Huacai Chen wrote:
>>> On Tue, May 7, 2024 at 9:40 AM maobibo <[email protected]> wrote:
>>>>
>>>>
>>>>
>>>> On 2024/5/6 下午10:17, Huacai Chen wrote:
>>>>> On Mon, May 6, 2024 at 6:05 PM maobibo <[email protected]> wrote:
>>>>>>
>>>>>>
>>>>>>
>>>>>> On 2024/5/6 下午5:40, Huacai Chen wrote:
>>>>>>> On Mon, May 6, 2024 at 5:35 PM maobibo <[email protected]> wrote:
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> On 2024/5/6 下午4:59, Huacai Chen wrote:
>>>>>>>>> On Mon, May 6, 2024 at 4:18 PM maobibo <[email protected]> wrote:
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> On 2024/5/6 下午3:06, Huacai Chen wrote:
>>>>>>>>>>> Hi, Bibo,
>>>>>>>>>>>
>>>>>>>>>>> On Mon, May 6, 2024 at 2:36 PM maobibo <[email protected]> wrote:
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>> On 2024/5/6 上午9:49, Huacai Chen wrote:
>>>>>>>>>>>>> Hi, Bibo,
>>>>>>>>>>>>>
>>>>>>>>>>>>> On Sun, Apr 28, 2024 at 6:05 PM Bibo Mao <[email protected]> wrote:
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> Physical cpuid is used for interrupt routing for irqchips such as
>>>>>>>>>>>>>> ipi/msi/extioi interrupt controller. And physical cpuid is stored
>>>>>>>>>>>>>> at CSR register LOONGARCH_CSR_CPUID, it can not be changed once vcpu
>>>>>>>>>>>>>> is created and physical cpuid of two vcpus cannot be the same.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> Different irqchips have different size declaration about physical cpuid,
>>>>>>>>>>>>>> max cpuid value for CSR LOONGARCH_CSR_CPUID on 3A5000 is 512, max cpuid
>>>>>>>>>>>>>> supported by IPI hardware is 1024, 256 for extioi irqchip, and 65536
>>>>>>>>>>>>>> for MSI irqchip.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> The smallest value from all interrupt controllers is selected now,
>>>>>>>>>>>>>> and the max cpuid size is defines as 256 by KVM which comes from
>>>>>>>>>>>>>> extioi irqchip.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> Signed-off-by: Bibo Mao <[email protected]>
>>>>>>>>>>>>>> ---
>>>>>>>>>>>>>> arch/loongarch/include/asm/kvm_host.h | 26 ++++++++
>>>>>>>>>>>>>> arch/loongarch/include/asm/kvm_vcpu.h | 1 +
>>>>>>>>>>>>>> arch/loongarch/kvm/vcpu.c | 93 ++++++++++++++++++++++++++-
>>>>>>>>>>>>>> arch/loongarch/kvm/vm.c | 11 ++++
>>>>>>>>>>>>>> 4 files changed, 130 insertions(+), 1 deletion(-)
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> diff --git a/arch/loongarch/include/asm/kvm_host.h b/arch/loongarch/include/asm/kvm_host.h
>>>>>>>>>>>>>> index 2d62f7b0d377..3ba16ef1fe69 100644
>>>>>>>>>>>>>> --- a/arch/loongarch/include/asm/kvm_host.h
>>>>>>>>>>>>>> +++ b/arch/loongarch/include/asm/kvm_host.h
>>>>>>>>>>>>>> @@ -64,6 +64,30 @@ struct kvm_world_switch {
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> #define MAX_PGTABLE_LEVELS 4
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> +/*
>>>>>>>>>>>>>> + * Physical cpu id is used for interrupt routing, there are different
>>>>>>>>>>>>>> + * definitions about physical cpuid on different hardwares.
>>>>>>>>>>>>>> + * For LOONGARCH_CSR_CPUID register, max cpuid size if 512
>>>>>>>>>>>>>> + * For IPI HW, max dest CPUID size 1024
>>>>>>>>>>>>>> + * For extioi interrupt controller, max dest CPUID size is 256
>>>>>>>>>>>>>> + * For MSI interrupt controller, max supported CPUID size is 65536
>>>>>>>>>>>>>> + *
>>>>>>>>>>>>>> + * Currently max CPUID is defined as 256 for KVM hypervisor, in future
>>>>>>>>>>>>>> + * it will be expanded to 4096, including 16 packages at most. And every
>>>>>>>>>>>>>> + * package supports at most 256 vcpus
>>>>>>>>>>>>>> + */
>>>>>>>>>>>>>> +#define KVM_MAX_PHYID 256
>>>>>>>>>>>>>> +
>>>>>>>>>>>>>> +struct kvm_phyid_info {
>>>>>>>>>>>>>> + struct kvm_vcpu *vcpu;
>>>>>>>>>>>>>> + bool enabled;
>>>>>>>>>>>>>> +};
>>>>>>>>>>>>>> +
>>>>>>>>>>>>>> +struct kvm_phyid_map {
>>>>>>>>>>>>>> + int max_phyid;
>>>>>>>>>>>>>> + struct kvm_phyid_info phys_map[KVM_MAX_PHYID];
>>>>>>>>>>>>>> +};
>>>>>>>>>>>>>> +
>>>>>>>>>>>>>> struct kvm_arch {
>>>>>>>>>>>>>> /* Guest physical mm */
>>>>>>>>>>>>>> kvm_pte_t *pgd;
>>>>>>>>>>>>>> @@ -71,6 +95,8 @@ struct kvm_arch {
>>>>>>>>>>>>>> unsigned long invalid_ptes[MAX_PGTABLE_LEVELS];
>>>>>>>>>>>>>> unsigned int pte_shifts[MAX_PGTABLE_LEVELS];
>>>>>>>>>>>>>> unsigned int root_level;
>>>>>>>>>>>>>> + spinlock_t phyid_map_lock;
>>>>>>>>>>>>>> + struct kvm_phyid_map *phyid_map;
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> s64 time_offset;
>>>>>>>>>>>>>> struct kvm_context __percpu *vmcs;
>>>>>>>>>>>>>> diff --git a/arch/loongarch/include/asm/kvm_vcpu.h b/arch/loongarch/include/asm/kvm_vcpu.h
>>>>>>>>>>>>>> index 0cb4fdb8a9b5..9f53950959da 100644
>>>>>>>>>>>>>> --- a/arch/loongarch/include/asm/kvm_vcpu.h
>>>>>>>>>>>>>> +++ b/arch/loongarch/include/asm/kvm_vcpu.h
>>>>>>>>>>>>>> @@ -81,6 +81,7 @@ void kvm_save_timer(struct kvm_vcpu *vcpu);
>>>>>>>>>>>>>> void kvm_restore_timer(struct kvm_vcpu *vcpu);
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> int kvm_vcpu_ioctl_interrupt(struct kvm_vcpu *vcpu, struct kvm_interrupt *irq);
>>>>>>>>>>>>>> +struct kvm_vcpu *kvm_get_vcpu_by_cpuid(struct kvm *kvm, int cpuid);
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> /*
>>>>>>>>>>>>>> * Loongarch KVM guest interrupt handling
>>>>>>>>>>>>>> diff --git a/arch/loongarch/kvm/vcpu.c b/arch/loongarch/kvm/vcpu.c
>>>>>>>>>>>>>> index 3a8779065f73..b633fd28b8db 100644
>>>>>>>>>>>>>> --- a/arch/loongarch/kvm/vcpu.c
>>>>>>>>>>>>>> +++ b/arch/loongarch/kvm/vcpu.c
>>>>>>>>>>>>>> @@ -274,6 +274,95 @@ static int _kvm_getcsr(struct kvm_vcpu *vcpu, unsigned int id, u64 *val)
>>>>>>>>>>>>>> return 0;
>>>>>>>>>>>>>> }
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> +static inline int kvm_set_cpuid(struct kvm_vcpu *vcpu, u64 val)
>>>>>>>>>>>>>> +{
>>>>>>>>>>>>>> + int cpuid;
>>>>>>>>>>>>>> + struct loongarch_csrs *csr = vcpu->arch.csr;
>>>>>>>>>>>>>> + struct kvm_phyid_map *map;
>>>>>>>>>>>>>> +
>>>>>>>>>>>>>> + if (val >= KVM_MAX_PHYID)
>>>>>>>>>>>>>> + return -EINVAL;
>>>>>>>>>>>>>> +
>>>>>>>>>>>>>> + cpuid = kvm_read_sw_gcsr(csr, LOONGARCH_CSR_ESTAT);
>>>>>>>>>>>>>> + map = vcpu->kvm->arch.phyid_map;
>>>>>>>>>>>>>> + spin_lock(&vcpu->kvm->arch.phyid_map_lock);
>>>>>>>>>>>>>> + if (map->phys_map[cpuid].enabled) {
>>>>>>>>>>>>>> + /*
>>>>>>>>>>>>>> + * Cpuid is already set before
>>>>>>>>>>>>>> + * Forbid changing different cpuid at runtime
>>>>>>>>>>>>>> + */
>>>>>>>>>>>>>> + if (cpuid != val) {
>>>>>>>>>>>>>> + /*
>>>>>>>>>>>>>> + * Cpuid 0 is initial value for vcpu, maybe invalid
>>>>>>>>>>>>>> + * unset value for vcpu
>>>>>>>>>>>>>> + */
>>>>>>>>>>>>>> + if (cpuid) {
>>>>>>>>>>>>>> + spin_unlock(&vcpu->kvm->arch.phyid_map_lock);
>>>>>>>>>>>>>> + return -EINVAL;
>>>>>>>>>>>>>> + }
>>>>>>>>>>>>>> + } else {
>>>>>>>>>>>>>> + /* Discard duplicated cpuid set */
>>>>>>>>>>>>>> + spin_unlock(&vcpu->kvm->arch.phyid_map_lock);
>>>>>>>>>>>>>> + return 0;
>>>>>>>>>>>>>> + }
>>>>>>>>>>>>>> + }
>>>>>>>>>>>>> I have changed the logic and comments when I apply, you can double
>>>>>>>>>>>>> check whether it is correct.
>>>>>>>>>>>> I checkout the latest version, the modification in function
>>>>>>>>>>>> kvm_set_cpuid() is good for me.
>>>>>>>>>>> Now the modified version is like this:
>>>>>>>>>>>
>>>>>>>>>>> + if (map->phys_map[cpuid].enabled) {
>>>>>>>>>>> + /* Discard duplicated CPUID set operation */
>>>>>>>>>>> + if (cpuid == val) {
>>>>>>>>>>> + spin_unlock(&vcpu->kvm->arch.phyid_map_lock);
>>>>>>>>>>> + return 0;
>>>>>>>>>>> + }
>>>>>>>>>>> +
>>>>>>>>>>> + /*
>>>>>>>>>>> + * CPUID is already set before
>>>>>>>>>>> + * Forbid changing different CPUID at runtime
>>>>>>>>>>> + * But CPUID 0 is the initial value for vcpu, so allow
>>>>>>>>>>> + * changing from 0 to others
>>>>>>>>>>> + */
>>>>>>>>>>> + if (cpuid) {
>>>>>>>>>>> + spin_unlock(&vcpu->kvm->arch.phyid_map_lock);
>>>>>>>>>>> + return -EINVAL;
>>>>>>>>>>> + }
>>>>>>>>>>> + }
>>>>>>>>>>> But I still doubt whether we should allow changing from 0 to others
>>>>>>>>>>> while map->phys_map[cpuid].enabled is 1.
>>>>>>>>>> It is necessary since the default sw cpuid is zero :-( And we can
>>>>>>>>>> optimize it in later, such as set INVALID cpuid in function
>>>>>>>>>> kvm_arch_vcpu_create() and logic will be simple in function kvm_set_cpuid().
>>>>>>>>> In my opinion, if a vcpu with a uninitialized default physid=0, then
>>>>>>>>> map->phys_map[cpuid].enabled should be 0, then code won't come here.
>>>>>>>>> And if a vcpu with a real physid=0, then map->phys_map[cpuid].enabled
>>>>>>>>> is 1, but we shouldn't allow it to change physid in this case.
>>>>>>>> yes, that is actually a problem.
>>>>>>>>
>>>>>>>> vcpu0 firstly set physid=0, and vcpu0 set physid=1 again is not allowed.
>>>>>>>> vcpu0 firstly set physid=0, and vcpu1 set physid=1 is allowed.
>>>>>>>
>>>>>>> So can we simply drop the if (cpuid) checking? That means:
>>>>>>> + if (map->phys_map[cpuid].enabled) {
>>>>>>> + /* Discard duplicated CPUID set operation */
>>>>>>> + if (cpuid == val) {
>>>>>>> + spin_unlock(&vcpu->kvm->arch.phyid_map_lock);
>>>>>>> + return 0;
>>>>>>> + }
>>>>>>> +
>>>>>>> + spin_unlock(&vcpu->kvm->arch.phyid_map_lock);
>>>>>>> + return -EINVAL;
>>>>>>> + }
>>>>>> yes, the similar modification such as following, since the secondary
>>>>>> scenario should be allowed.
>>>>>> "vcpu0 firstly set physid=0, and vcpu1 set physid=1 is allowed though
>>>>>> default sw cpuid is zero"
>>>>>>
>>>>>> --- a/arch/loongarch/kvm/vcpu.c
>>>>>> +++ b/arch/loongarch/kvm/vcpu.c
>>>>>> @@ -272,7 +272,7 @@ static inline int kvm_set_cpuid(struct kvm_vcpu
>>>>>> *vcpu, u64 val)
>>>>>> cpuid = kvm_read_sw_gcsr(csr, LOONGARCH_CSR_CPUID);
>>>>>>
>>>>>> spin_lock(&vcpu->kvm->arch.phyid_map_lock);
>>>>>> - if (map->phys_map[cpuid].enabled) {
>>>>>> + if ((cpuid != KVM_MAX_PHYID) && map->phys_map[cpuid].enabled) {
>>>>>> /* Discard duplicated CPUID set operation */
>>>>>> if (cpuid == val) {
>>>>>> spin_unlock(&vcpu->kvm->arch.phyid_map_lock);
>>>>>> @@ -282,13 +282,9 @@ static inline int kvm_set_cpuid(struct kvm_vcpu
>>>>>> *vcpu, u64 val)
>>>>>> /*
>>>>>> * CPUID is already set before
>>>>>> * Forbid changing different CPUID at runtime
>>>>>> - * But CPUID 0 is the initial value for vcpu, so allow
>>>>>> - * changing from 0 to others
>>>>>> */
>>>>>> - if (cpuid) {
>>>>>> - spin_unlock(&vcpu->kvm->arch.phyid_map_lock);
>>>>>> - return -EINVAL;
>>>>>> - }
>>>>>> + spin_unlock(&vcpu->kvm->arch.phyid_map_lock);
>>>>>> + return -EINVAL;
>>>>>> }
>>>>>>
>>>>>> if (map->phys_map[val].enabled) {
>>>>>> @@ -1029,6 +1025,7 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
>>>>>>
>>>>>> /* Set cpuid */
>>>>>> kvm_write_sw_gcsr(csr, LOONGARCH_CSR_TMID, vcpu->vcpu_id);
>>>>>> + kvm_write_sw_gcsr(csr, LOONGARCH_CSR_CPUID, KVM_MAX_PHYID);
>>>>>>
>>>>>> /* Start with no pending virtual guest interrupts */
>>>>>> csr->csrs[LOONGARCH_CSR_GINTC] = 0;
>>>>> Very nice, but I think kvm_drop_cpuid() should also set to KVM_MAX_PHYID.
>>>>> Now I update my loongarch-kvm branch, you can test it again, and hope
>>>>> it is in the perfect status.
>>>> I sync and test the latest code from loongarch-kvm, pv ipi works well
>>>> with 256 vcpus. And the code looks good to me, thanks for your review in
>>>> short time.
>>> OK, if SWDBG also works well, I will send PR to Paolo tomorrow.
>> yes, sw debug works well with patch from qemu. And I will refresh patch
>> to qemu after it is merged.
>>
>> https://lore.kernel.org/all/[email protected]/
>>
>> --- a/configs/targets/loongarch64-softmmu.mak
>> +++ b/configs/targets/loongarch64-softmmu.mak
>> @@ -1,5 +1,6 @@
>> TARGET_ARCH=loongarch64
>> TARGET_BASE_ARCH=loongarch
>> TARGET_SUPPORTS_MTTCG=y
>> +TARGET_KVM_HAVE_GUEST_DEBUG=y
>> TARGET_XML_FILES= gdb-xml/loongarch-base32.xml
>> gdb-xml/loongarch-base64.xml gdb-xml/loongarch-fpu.xml
>> TARGET_NEED_FDT=y
> Not enough, we need kvm_arch_update_guest_debug() and some other functions.
yes, the RFC patch on qemu side is posted at website:
https://lore.kernel.org/all/[email protected]/

>
> Huacai
>
>>
>> Regards
>> Bibo Mao
>>>
>>> Huacai
>>>
>>>>
>>>> Regards
>>>> Bibo Mao
>>>>>
>>>>> Huacai
>>>>>>
>>>>>>
>>>>>>>
>>>>>>> Huacai
>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>>
>>>>>>>>> Huacai
>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> Regards
>>>>>>>>>> Bibo Mao
>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> Huacai
>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>>> +
>>>>>>>>>>>>>> + if (map->phys_map[val].enabled) {
>>>>>>>>>>>>>> + /*
>>>>>>>>>>>>>> + * New cpuid is already set with other vcpu
>>>>>>>>>>>>>> + * Forbid sharing the same cpuid between different vcpus
>>>>>>>>>>>>>> + */
>>>>>>>>>>>>>> + if (map->phys_map[val].vcpu != vcpu) {
>>>>>>>>>>>>>> + spin_unlock(&vcpu->kvm->arch.phyid_map_lock);
>>>>>>>>>>>>>> + return -EINVAL;
>>>>>>>>>>>>>> + }
>>>>>>>>>>>>>> +
>>>>>>>>>>>>>> + /* Discard duplicated cpuid set operation*/
>>>>>>>>>>>>>> + spin_unlock(&vcpu->kvm->arch.phyid_map_lock);
>>>>>>>>>>>>>> + return 0;
>>>>>>>>>>>>>> + }
>>>>>>>>>>>>>> +
>>>>>>>>>>>>>> + kvm_write_sw_gcsr(csr, LOONGARCH_CSR_CPUID, val);
>>>>>>>>>>>>>> + map->phys_map[val].enabled = true;
>>>>>>>>>>>>>> + map->phys_map[val].vcpu = vcpu;
>>>>>>>>>>>>>> + if (map->max_phyid < val)
>>>>>>>>>>>>>> + map->max_phyid = val;
>>>>>>>>>>>>>> + spin_unlock(&vcpu->kvm->arch.phyid_map_lock);
>>>>>>>>>>>>>> + return 0;
>>>>>>>>>>>>>> +}
>>>>>>>>>>>>>> +
>>>>>>>>>>>>>> +struct kvm_vcpu *kvm_get_vcpu_by_cpuid(struct kvm *kvm, int cpuid)
>>>>>>>>>>>>>> +{
>>>>>>>>>>>>>> + struct kvm_phyid_map *map;
>>>>>>>>>>>>>> +
>>>>>>>>>>>>>> + if (cpuid >= KVM_MAX_PHYID)
>>>>>>>>>>>>>> + return NULL;
>>>>>>>>>>>>>> +
>>>>>>>>>>>>>> + map = kvm->arch.phyid_map;
>>>>>>>>>>>>>> + if (map->phys_map[cpuid].enabled)
>>>>>>>>>>>>>> + return map->phys_map[cpuid].vcpu;
>>>>>>>>>>>>>> +
>>>>>>>>>>>>>> + return NULL;
>>>>>>>>>>>>>> +}
>>>>>>>>>>>>>> +
>>>>>>>>>>>>>> +static inline void kvm_drop_cpuid(struct kvm_vcpu *vcpu)
>>>>>>>>>>>>>> +{
>>>>>>>>>>>>>> + int cpuid;
>>>>>>>>>>>>>> + struct loongarch_csrs *csr = vcpu->arch.csr;
>>>>>>>>>>>>>> + struct kvm_phyid_map *map;
>>>>>>>>>>>>>> +
>>>>>>>>>>>>>> + map = vcpu->kvm->arch.phyid_map;
>>>>>>>>>>>>>> + cpuid = kvm_read_sw_gcsr(csr, LOONGARCH_CSR_ESTAT);
>>>>>>>>>>>>>> + if (cpuid >= KVM_MAX_PHYID)
>>>>>>>>>>>>>> + return;
>>>>>>>>>>>>>> +
>>>>>>>>>>>>>> + if (map->phys_map[cpuid].enabled) {
>>>>>>>>>>>>>> + map->phys_map[cpuid].vcpu = NULL;
>>>>>>>>>>>>>> + map->phys_map[cpuid].enabled = false;
>>>>>>>>>>>>>> + kvm_write_sw_gcsr(csr, LOONGARCH_CSR_CPUID, 0);
>>>>>>>>>>>>>> + }
>>>>>>>>>>>>>> +}
>>>>>>>>>>>>> While kvm_set_cpuid() is protected by a spinlock, do kvm_drop_cpuid()
>>>>>>>>>>>>> and kvm_get_vcpu_by_cpuid() also need it?
>>>>>>>>>>>>>
>>>>>>>>>>>> It is good to me that spinlock is added in function kvm_drop_cpuid().
>>>>>>>>>>>> And thinks for the efforts.
>>>>>>>>>>>>
>>>>>>>>>>>> Regards
>>>>>>>>>>>> Bibo Mao
>>>>>>>>>>>>>> +
>>>>>>>>>>>>>> static int _kvm_setcsr(struct kvm_vcpu *vcpu, unsigned int id, u64 val)
>>>>>>>>>>>>>> {
>>>>>>>>>>>>>> int ret = 0, gintc;
>>>>>>>>>>>>>> @@ -291,7 +380,8 @@ static int _kvm_setcsr(struct kvm_vcpu *vcpu, unsigned int id, u64 val)
>>>>>>>>>>>>>> kvm_set_sw_gcsr(csr, LOONGARCH_CSR_ESTAT, gintc);
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> return ret;
>>>>>>>>>>>>>> - }
>>>>>>>>>>>>>> + } else if (id == LOONGARCH_CSR_CPUID)
>>>>>>>>>>>>>> + return kvm_set_cpuid(vcpu, val);
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> kvm_write_sw_gcsr(csr, id, val);
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> @@ -943,6 +1033,7 @@ void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu)
>>>>>>>>>>>>>> hrtimer_cancel(&vcpu->arch.swtimer);
>>>>>>>>>>>>>> kvm_mmu_free_memory_cache(&vcpu->arch.mmu_page_cache);
>>>>>>>>>>>>>> kfree(vcpu->arch.csr);
>>>>>>>>>>>>>> + kvm_drop_cpuid(vcpu);
>>>>>>>>>>>>> I think this line should be before the above kfree(), otherwise you
>>>>>>>>>>>>> get a "use after free".
>>>>>>>>>>>>>
>>>>>>>>>>>>> Huacai
>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> /*
>>>>>>>>>>>>>> * If the vCPU is freed and reused as another vCPU, we don't want the
>>>>>>>>>>>>>> diff --git a/arch/loongarch/kvm/vm.c b/arch/loongarch/kvm/vm.c
>>>>>>>>>>>>>> index 0a37f6fa8f2d..6006a28653ad 100644
>>>>>>>>>>>>>> --- a/arch/loongarch/kvm/vm.c
>>>>>>>>>>>>>> +++ b/arch/loongarch/kvm/vm.c
>>>>>>>>>>>>>> @@ -30,6 +30,14 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
>>>>>>>>>>>>>> if (!kvm->arch.pgd)
>>>>>>>>>>>>>> return -ENOMEM;
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> + kvm->arch.phyid_map = kvzalloc(sizeof(struct kvm_phyid_map),
>>>>>>>>>>>>>> + GFP_KERNEL_ACCOUNT);
>>>>>>>>>>>>>> + if (!kvm->arch.phyid_map) {
>>>>>>>>>>>>>> + free_page((unsigned long)kvm->arch.pgd);
>>>>>>>>>>>>>> + kvm->arch.pgd = NULL;
>>>>>>>>>>>>>> + return -ENOMEM;
>>>>>>>>>>>>>> + }
>>>>>>>>>>>>>> +
>>>>>>>>>>>>>> kvm_init_vmcs(kvm);
>>>>>>>>>>>>>> kvm->arch.gpa_size = BIT(cpu_vabits - 1);
>>>>>>>>>>>>>> kvm->arch.root_level = CONFIG_PGTABLE_LEVELS - 1;
>>>>>>>>>>>>>> @@ -44,6 +52,7 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
>>>>>>>>>>>>>> for (i = 0; i <= kvm->arch.root_level; i++)
>>>>>>>>>>>>>> kvm->arch.pte_shifts[i] = PAGE_SHIFT + i * (PAGE_SHIFT - 3);
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> + spin_lock_init(&kvm->arch.phyid_map_lock);
>>>>>>>>>>>>>> return 0;
>>>>>>>>>>>>>> }
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> @@ -51,7 +60,9 @@ void kvm_arch_destroy_vm(struct kvm *kvm)
>>>>>>>>>>>>>> {
>>>>>>>>>>>>>> kvm_destroy_vcpus(kvm);
>>>>>>>>>>>>>> free_page((unsigned long)kvm->arch.pgd);
>>>>>>>>>>>>>> + kvfree(kvm->arch.phyid_map);
>>>>>>>>>>>>>> kvm->arch.pgd = NULL;
>>>>>>>>>>>>>> + kvm->arch.phyid_map = NULL;
>>>>>>>>>>>>>> }
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
>>>>>>>>>>>>>> --
>>>>>>>>>>>>>> 2.39.3
>>>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>
>>>>>>
>>>>
>>>>
>>
>>