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Message-ID: <CAAhV-H5oS+KrcGH+1wJCGKCjs2VKHkWyZ5QnorPjFMuE_eBb3g@mail.gmail.com>
Date: Sat, 6 Jul 2024 17:41:59 +0800
From: Huacai Chen <chenhuacai@...nel.org>
To: maobibo <maobibo@...ngson.cn>
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 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.
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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