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Message-ID: <1aa110a8-28b9-d1d0-4b39-bc894b31f26c@loongson.cn>
Date: Sat, 6 Jul 2024 14:59:21 +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
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().
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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