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Message-ID: <ae21f9ef-e043-0f8c-b088-6645fc1f3c30@loongson.cn>
Date: Mon, 8 Jul 2024 09:16:04 +0800
From: maobibo <maobibo@...ngson.cn>
To: Huacai Chen <chenhuacai@...nel.org>
Cc: Tianrui Zhao <zhaotianrui@...ngson.cn>, Juergen Gross <jgross@...e.com>,
kvm@...r.kernel.org, loongarch@...ts.linux.dev,
linux-kernel@...r.kernel.org, x86@...nel.org, virtualization@...ts.linux.dev
Subject: Re: [PATCH v4 1/2] LoongArch: KVM: Add steal time support in kvm side
On 2024/7/6 下午5:41, Huacai Chen wrote:
> On Sat, Jul 6, 2024 at 2:59 PM maobibo <maobibo@...ngson.cn> wrote:
>>
>> Huacai,
>>
>> On 2024/7/6 上午11:00, Huacai Chen wrote:
>>> Hi, Bibo,
>>>
>>> On Fri, May 24, 2024 at 3:38 PM Bibo Mao <maobibo@...ngson.cn> wrote:
>>>>
>>>> Steal time feature is added here in kvm side, VM can search supported
>>>> features provided by KVM hypervisor, feature KVM_FEATURE_STEAL_TIME
>>>> is added here. Like x86, steal time structure is saved in guest memory,
>>>> one hypercall function KVM_HCALL_FUNC_NOTIFY is added to notify KVM to
>>>> enable the feature.
>>>>
>>>> One cpu attr ioctl command KVM_LOONGARCH_VCPU_PVTIME_CTRL is added to
>>>> save and restore base address of steal time structure when VM is migrated.
>>>>
>>>> Signed-off-by: Bibo Mao <maobibo@...ngson.cn>
>>>> ---
>>>> arch/loongarch/include/asm/kvm_host.h | 7 ++
>>>> arch/loongarch/include/asm/kvm_para.h | 10 ++
>>>> arch/loongarch/include/asm/kvm_vcpu.h | 4 +
>>>> arch/loongarch/include/asm/loongarch.h | 1 +
>>>> arch/loongarch/include/uapi/asm/kvm.h | 4 +
>>>> arch/loongarch/kvm/Kconfig | 1 +
>>>> arch/loongarch/kvm/exit.c | 38 +++++++-
>>>> arch/loongarch/kvm/vcpu.c | 124 +++++++++++++++++++++++++
>>>> 8 files changed, 187 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/arch/loongarch/include/asm/kvm_host.h b/arch/loongarch/include/asm/kvm_host.h
>>>> index c87b6ea0ec47..2eb2f7572023 100644
>>>> --- a/arch/loongarch/include/asm/kvm_host.h
>>>> +++ b/arch/loongarch/include/asm/kvm_host.h
>>>> @@ -30,6 +30,7 @@
>>>> #define KVM_PRIVATE_MEM_SLOTS 0
>>>>
>>>> #define KVM_HALT_POLL_NS_DEFAULT 500000
>>>> +#define KVM_REQ_STEAL_UPDATE KVM_ARCH_REQ(1)
>>>>
>>>> #define KVM_GUESTDBG_SW_BP_MASK \
>>>> (KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_USE_SW_BP)
>>>> @@ -201,6 +202,12 @@ struct kvm_vcpu_arch {
>>>> struct kvm_mp_state mp_state;
>>>> /* cpucfg */
>>>> u32 cpucfg[KVM_MAX_CPUCFG_REGS];
>>>> + /* paravirt steal time */
>>>> + struct {
>>>> + u64 guest_addr;
>>>> + u64 last_steal;
>>>> + struct gfn_to_hva_cache cache;
>>>> + } st;
>>>> };
>>>>
>>>> static inline unsigned long readl_sw_gcsr(struct loongarch_csrs *csr, int reg)
>>>> diff --git a/arch/loongarch/include/asm/kvm_para.h b/arch/loongarch/include/asm/kvm_para.h
>>>> index 4ba2312e5f8c..a9ba8185d4af 100644
>>>> --- a/arch/loongarch/include/asm/kvm_para.h
>>>> +++ b/arch/loongarch/include/asm/kvm_para.h
>>>> @@ -14,6 +14,7 @@
>>>>
>>>> #define KVM_HCALL_SERVICE HYPERCALL_ENCODE(HYPERVISOR_KVM, KVM_HCALL_CODE_SERVICE)
>>>> #define KVM_HCALL_FUNC_IPI 1
>>>> +#define KVM_HCALL_FUNC_NOTIFY 2
>>>>
>>>> #define KVM_HCALL_SWDBG HYPERCALL_ENCODE(HYPERVISOR_KVM, KVM_HCALL_CODE_SWDBG)
>>>>
>>>> @@ -24,6 +25,15 @@
>>>> #define KVM_HCALL_INVALID_CODE -1UL
>>>> #define KVM_HCALL_INVALID_PARAMETER -2UL
>>>>
>>>> +#define KVM_STEAL_PHYS_VALID BIT_ULL(0)
>>>> +#define KVM_STEAL_PHYS_MASK GENMASK_ULL(63, 6)
>>>> +struct kvm_steal_time {
>>>> + __u64 steal;
>>>> + __u32 version;
>>>> + __u32 flags;
>>> I found that x86 has a preempted field here, in our internal repo the
>>> LoongArch version also has this field. Moreover,
>>> kvm_steal_time_set_preempted() and kvm_steal_time_clear_preempted()
>>> seems needed.
>> By my understanding, macro vcpu_is_preempted() is used together with pv
>> spinlock, and pv spinlock depends on pv stealtime. So I think preempted
>> flag is not part of pv stealtime, it is part of pv spinlock.
>>
>> We are going to add preempted field if pv spinlock is added.
>>>
>>>> + __u32 pad[12];
>>>> +};
>>>> +
>>>> /*
>>>> * Hypercall interface for KVM hypervisor
>>>> *
>>>> diff --git a/arch/loongarch/include/asm/kvm_vcpu.h b/arch/loongarch/include/asm/kvm_vcpu.h
>>>> index 590a92cb5416..d7e51300a89f 100644
>>>> --- a/arch/loongarch/include/asm/kvm_vcpu.h
>>>> +++ b/arch/loongarch/include/asm/kvm_vcpu.h
>>>> @@ -120,4 +120,8 @@ static inline void kvm_write_reg(struct kvm_vcpu *vcpu, int num, unsigned long v
>>>> vcpu->arch.gprs[num] = val;
>>>> }
>>>>
>>>> +static inline bool kvm_pvtime_supported(void)
>>>> +{
>>>> + return !!sched_info_on();
>>>> +}
>>>> #endif /* __ASM_LOONGARCH_KVM_VCPU_H__ */
>>>> diff --git a/arch/loongarch/include/asm/loongarch.h b/arch/loongarch/include/asm/loongarch.h
>>>> index eb09adda54b7..7a4633ef284b 100644
>>>> --- a/arch/loongarch/include/asm/loongarch.h
>>>> +++ b/arch/loongarch/include/asm/loongarch.h
>>>> @@ -169,6 +169,7 @@
>>>> #define KVM_SIGNATURE "KVM\0"
>>>> #define CPUCFG_KVM_FEATURE (CPUCFG_KVM_BASE + 4)
>>>> #define KVM_FEATURE_IPI BIT(1)
>>>> +#define KVM_FEATURE_STEAL_TIME BIT(2)
>>>>
>>>> #ifndef __ASSEMBLY__
>>>>
>>>> diff --git a/arch/loongarch/include/uapi/asm/kvm.h b/arch/loongarch/include/uapi/asm/kvm.h
>>>> index f9abef382317..ddc5cab0ffd0 100644
>>>> --- a/arch/loongarch/include/uapi/asm/kvm.h
>>>> +++ b/arch/loongarch/include/uapi/asm/kvm.h
>>>> @@ -81,7 +81,11 @@ struct kvm_fpu {
>>>> #define LOONGARCH_REG_64(TYPE, REG) (TYPE | KVM_REG_SIZE_U64 | (REG << LOONGARCH_REG_SHIFT))
>>>> #define KVM_IOC_CSRID(REG) LOONGARCH_REG_64(KVM_REG_LOONGARCH_CSR, REG)
>>>> #define KVM_IOC_CPUCFG(REG) LOONGARCH_REG_64(KVM_REG_LOONGARCH_CPUCFG, REG)
>>>> +
>>>> +/* Device Control API on vcpu fd */
>>>> #define KVM_LOONGARCH_VCPU_CPUCFG 0
>>>> +#define KVM_LOONGARCH_VCPU_PVTIME_CTRL 1
>>>> +#define KVM_LOONGARCH_VCPU_PVTIME_GPA 0
>>>>
>>>> struct kvm_debug_exit_arch {
>>>> };
>>>> diff --git a/arch/loongarch/kvm/Kconfig b/arch/loongarch/kvm/Kconfig
>>>> index c4ef2b4d9797..248744b4d086 100644
>>>> --- a/arch/loongarch/kvm/Kconfig
>>>> +++ b/arch/loongarch/kvm/Kconfig
>>>> @@ -29,6 +29,7 @@ config KVM
>>>> select KVM_MMIO
>>>> select HAVE_KVM_READONLY_MEM
>>>> select KVM_XFER_TO_GUEST_WORK
>>>> + select SCHED_INFO
>>>> help
>>>> Support hosting virtualized guest machines using
>>>> hardware virtualization extensions. You will need
>>>> diff --git a/arch/loongarch/kvm/exit.c b/arch/loongarch/kvm/exit.c
>>>> index c86e099af5ca..e2abd97fb13f 100644
>>>> --- a/arch/loongarch/kvm/exit.c
>>>> +++ b/arch/loongarch/kvm/exit.c
>>>> @@ -24,7 +24,7 @@
>>>> static int kvm_emu_cpucfg(struct kvm_vcpu *vcpu, larch_inst inst)
>>>> {
>>>> int rd, rj;
>>>> - unsigned int index;
>>>> + unsigned int index, ret;
>>>>
>>>> if (inst.reg2_format.opcode != cpucfg_op)
>>>> return EMULATE_FAIL;
>>>> @@ -50,7 +50,10 @@ static int kvm_emu_cpucfg(struct kvm_vcpu *vcpu, larch_inst inst)
>>>> vcpu->arch.gprs[rd] = *(unsigned int *)KVM_SIGNATURE;
>>>> break;
>>>> case CPUCFG_KVM_FEATURE:
>>>> - vcpu->arch.gprs[rd] = KVM_FEATURE_IPI;
>>>> + ret = KVM_FEATURE_IPI;
>>>> + if (sched_info_on())
>>> What about replacing it with your helper function kvm_pvtime_supported()?
>> Sure, will replace it with helper function kvm_pvtime_supported().
> If you are sure this is the only issue, then needn't submit a new version.
OK, thanks.
By searching orginal submit of vcpu_is_preempt(), it can be located at
https://lore.kernel.org/lkml/1477642287-24104-1-git-send-email-xinhui.pan@linux.vnet.ibm.com/
It is separated one, only that is depends on pv-spinlock and
pv-stealtime. And there is no capability indicator for guest kernel, it
is enabled by default.
Regards
Bibo Mao
>
> Huacai
>
>>
>> Regards
>> Bibo Mao
>>>
>>> Huacai
>>>
>>>> + ret |= KVM_FEATURE_STEAL_TIME;
>>>> + vcpu->arch.gprs[rd] = ret;
>>>> break;
>>>> default:
>>>> vcpu->arch.gprs[rd] = 0;
>>>> @@ -687,6 +690,34 @@ static int kvm_handle_fpu_disabled(struct kvm_vcpu *vcpu)
>>>> return RESUME_GUEST;
>>>> }
>>>>
>>>> +static long kvm_save_notify(struct kvm_vcpu *vcpu)
>>>> +{
>>>> + unsigned long id, data;
>>>> +
>>>> + id = kvm_read_reg(vcpu, LOONGARCH_GPR_A1);
>>>> + data = kvm_read_reg(vcpu, LOONGARCH_GPR_A2);
>>>> + switch (id) {
>>>> + case KVM_FEATURE_STEAL_TIME:
>>>> + if (!kvm_pvtime_supported())
>>>> + return KVM_HCALL_INVALID_CODE;
>>>> +
>>>> + if (data & ~(KVM_STEAL_PHYS_MASK | KVM_STEAL_PHYS_VALID))
>>>> + return KVM_HCALL_INVALID_PARAMETER;
>>>> +
>>>> + vcpu->arch.st.guest_addr = data;
>>>> + if (!(data & KVM_STEAL_PHYS_VALID))
>>>> + break;
>>>> +
>>>> + vcpu->arch.st.last_steal = current->sched_info.run_delay;
>>>> + kvm_make_request(KVM_REQ_STEAL_UPDATE, vcpu);
>>>> + break;
>>>> + default:
>>>> + break;
>>>> + };
>>>> +
>>>> + return 0;
>>>> +};
>>>> +
>>>> /*
>>>> * kvm_handle_lsx_disabled() - Guest used LSX while disabled in root.
>>>> * @vcpu: Virtual CPU context.
>>>> @@ -758,6 +789,9 @@ static void kvm_handle_service(struct kvm_vcpu *vcpu)
>>>> kvm_send_pv_ipi(vcpu);
>>>> ret = KVM_HCALL_SUCCESS;
>>>> break;
>>>> + case KVM_HCALL_FUNC_NOTIFY:
>>>> + ret = kvm_save_notify(vcpu);
>>>> + break;
>>>> default:
>>>> ret = KVM_HCALL_INVALID_CODE;
>>>> break;
>>>> diff --git a/arch/loongarch/kvm/vcpu.c b/arch/loongarch/kvm/vcpu.c
>>>> index 9e8030d45129..382796f1d3e6 100644
>>>> --- a/arch/loongarch/kvm/vcpu.c
>>>> +++ b/arch/loongarch/kvm/vcpu.c
>>>> @@ -31,6 +31,117 @@ const struct kvm_stats_header kvm_vcpu_stats_header = {
>>>> sizeof(kvm_vcpu_stats_desc),
>>>> };
>>>>
>>>> +static void kvm_update_stolen_time(struct kvm_vcpu *vcpu)
>>>> +{
>>>> + struct kvm_steal_time __user *st;
>>>> + struct gfn_to_hva_cache *ghc;
>>>> + struct kvm_memslots *slots;
>>>> + gpa_t gpa;
>>>> + u64 steal;
>>>> + u32 version;
>>>> +
>>>> + ghc = &vcpu->arch.st.cache;
>>>> + gpa = vcpu->arch.st.guest_addr;
>>>> + if (!(gpa & KVM_STEAL_PHYS_VALID))
>>>> + return;
>>>> +
>>>> + gpa &= KVM_STEAL_PHYS_MASK;
>>>> + slots = kvm_memslots(vcpu->kvm);
>>>> + if (slots->generation != ghc->generation || gpa != ghc->gpa) {
>>>> + if (kvm_gfn_to_hva_cache_init(vcpu->kvm, ghc, gpa,
>>>> + sizeof(*st))) {
>>>> + ghc->gpa = INVALID_GPA;
>>>> + return;
>>>> + }
>>>> + }
>>>> +
>>>> + st = (struct kvm_steal_time __user *)ghc->hva;
>>>> + unsafe_get_user(version, &st->version, out);
>>>> + if (version & 1)
>>>> + version += 1;
>>>> + version += 1;
>>>> + unsafe_put_user(version, &st->version, out);
>>>> + smp_wmb();
>>>> +
>>>> + unsafe_get_user(steal, &st->steal, out);
>>>> + steal += current->sched_info.run_delay -
>>>> + vcpu->arch.st.last_steal;
>>>> + vcpu->arch.st.last_steal = current->sched_info.run_delay;
>>>> + unsafe_put_user(steal, &st->steal, out);
>>>> +
>>>> + smp_wmb();
>>>> + version += 1;
>>>> + unsafe_put_user(version, &st->version, out);
>>>> +out:
>>>> + mark_page_dirty_in_slot(vcpu->kvm, ghc->memslot, gpa_to_gfn(ghc->gpa));
>>>> +}
>>>> +
>>>> +static int kvm_loongarch_pvtime_has_attr(struct kvm_vcpu *vcpu,
>>>> + struct kvm_device_attr *attr)
>>>> +{
>>>> + if (!kvm_pvtime_supported() ||
>>>> + attr->attr != KVM_LOONGARCH_VCPU_PVTIME_GPA)
>>>> + return -ENXIO;
>>>> +
>>>> + return 0;
>>>> +}
>>>> +
>>>> +static int kvm_loongarch_pvtime_get_attr(struct kvm_vcpu *vcpu,
>>>> + struct kvm_device_attr *attr)
>>>> +{
>>>> + u64 __user *user = (u64 __user *)attr->addr;
>>>> + u64 gpa;
>>>> +
>>>> + if (!kvm_pvtime_supported() ||
>>>> + attr->attr != KVM_LOONGARCH_VCPU_PVTIME_GPA)
>>>> + return -ENXIO;
>>>> +
>>>> + gpa = vcpu->arch.st.guest_addr;
>>>> + if (put_user(gpa, user))
>>>> + return -EFAULT;
>>>> +
>>>> + return 0;
>>>> +}
>>>> +
>>>> +static int kvm_loongarch_pvtime_set_attr(struct kvm_vcpu *vcpu,
>>>> + struct kvm_device_attr *attr)
>>>> +{
>>>> + u64 __user *user = (u64 __user *)attr->addr;
>>>> + struct kvm *kvm = vcpu->kvm;
>>>> + u64 gpa;
>>>> + int ret = 0;
>>>> + int idx;
>>>> +
>>>> + if (!kvm_pvtime_supported() ||
>>>> + attr->attr != KVM_LOONGARCH_VCPU_PVTIME_GPA)
>>>> + return -ENXIO;
>>>> +
>>>> + if (get_user(gpa, user))
>>>> + return -EFAULT;
>>>> +
>>>> + if (gpa & ~(KVM_STEAL_PHYS_MASK | KVM_STEAL_PHYS_VALID))
>>>> + return -EINVAL;
>>>> +
>>>> + if (!(gpa & KVM_STEAL_PHYS_VALID)) {
>>>> + vcpu->arch.st.guest_addr = gpa;
>>>> + return 0;
>>>> + }
>>>> +
>>>> + /* Check the address is in a valid memslot */
>>>> + idx = srcu_read_lock(&kvm->srcu);
>>>> + if (kvm_is_error_hva(gfn_to_hva(kvm, gpa >> PAGE_SHIFT)))
>>>> + ret = -EINVAL;
>>>> + srcu_read_unlock(&kvm->srcu, idx);
>>>> +
>>>> + if (!ret) {
>>>> + vcpu->arch.st.guest_addr = gpa;
>>>> + vcpu->arch.st.last_steal = current->sched_info.run_delay;
>>>> + kvm_make_request(KVM_REQ_STEAL_UPDATE, vcpu);
>>>> + }
>>>> +
>>>> + return ret;
>>>> +}
>>>> +
>>>> /*
>>>> * kvm_check_requests - check and handle pending vCPU requests
>>>> *
>>>> @@ -48,6 +159,9 @@ static int kvm_check_requests(struct kvm_vcpu *vcpu)
>>>> if (kvm_dirty_ring_check_request(vcpu))
>>>> return RESUME_HOST;
>>>>
>>>> + if (kvm_check_request(KVM_REQ_STEAL_UPDATE, vcpu))
>>>> + kvm_update_stolen_time(vcpu);
>>>> +
>>>> return RESUME_GUEST;
>>>> }
>>>>
>>>> @@ -671,6 +785,9 @@ static int kvm_loongarch_vcpu_has_attr(struct kvm_vcpu *vcpu,
>>>> case KVM_LOONGARCH_VCPU_CPUCFG:
>>>> ret = kvm_loongarch_cpucfg_has_attr(vcpu, attr);
>>>> break;
>>>> + case KVM_LOONGARCH_VCPU_PVTIME_CTRL:
>>>> + ret = kvm_loongarch_pvtime_has_attr(vcpu, attr);
>>>> + break;
>>>> default:
>>>> break;
>>>> }
>>>> @@ -703,6 +820,9 @@ static int kvm_loongarch_vcpu_get_attr(struct kvm_vcpu *vcpu,
>>>> case KVM_LOONGARCH_VCPU_CPUCFG:
>>>> ret = kvm_loongarch_get_cpucfg_attr(vcpu, attr);
>>>> break;
>>>> + case KVM_LOONGARCH_VCPU_PVTIME_CTRL:
>>>> + ret = kvm_loongarch_pvtime_get_attr(vcpu, attr);
>>>> + break;
>>>> default:
>>>> break;
>>>> }
>>>> @@ -725,6 +845,9 @@ static int kvm_loongarch_vcpu_set_attr(struct kvm_vcpu *vcpu,
>>>> case KVM_LOONGARCH_VCPU_CPUCFG:
>>>> ret = kvm_loongarch_cpucfg_set_attr(vcpu, attr);
>>>> break;
>>>> + case KVM_LOONGARCH_VCPU_PVTIME_CTRL:
>>>> + ret = kvm_loongarch_pvtime_set_attr(vcpu, attr);
>>>> + break;
>>>> default:
>>>> break;
>>>> }
>>>> @@ -1084,6 +1207,7 @@ static int _kvm_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
>>>>
>>>> /* Control guest page CCA attribute */
>>>> change_csr_gcfg(CSR_GCFG_MATC_MASK, CSR_GCFG_MATC_ROOT);
>>>> + kvm_make_request(KVM_REQ_STEAL_UPDATE, vcpu);
>>>>
>>>> /* Don't bother restoring registers multiple times unless necessary */
>>>> if (vcpu->arch.aux_inuse & KVM_LARCH_HWCSR_USABLE)
>>>> --
>>>> 2.39.3
>>>>
>>
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