On Wed, Apr 27, 2022 at 12:23 AM Atish Patra <atishp@xxxxxxxxxxxx> wrote: > > Sstc extension allows the guest to program the vstimecmp CSR directly > instead of making an SBI call to the hypervisor to program the next > event. The timer interrupt is also directly injected to the guest by > the hardware in this case. To maintain backward compatibility, the > hypervisors also update the vstimecmp in an SBI set_time call if > the hardware supports it. Thus, the older kernels in guest also > take advantage of the sstc extension. > > Signed-off-by: Atish Patra <atishp@xxxxxxxxxxxx> > --- > arch/riscv/include/asm/kvm_host.h | 1 + > arch/riscv/include/asm/kvm_vcpu_timer.h | 8 +- > arch/riscv/include/uapi/asm/kvm.h | 1 + > arch/riscv/kvm/main.c | 12 ++- > arch/riscv/kvm/vcpu.c | 5 +- > arch/riscv/kvm/vcpu_timer.c | 138 +++++++++++++++++++++++- > 6 files changed, 159 insertions(+), 6 deletions(-) > > diff --git a/arch/riscv/include/asm/kvm_host.h b/arch/riscv/include/asm/kvm_host.h > index 78da839657e5..50a97c821f83 100644 > --- a/arch/riscv/include/asm/kvm_host.h > +++ b/arch/riscv/include/asm/kvm_host.h > @@ -135,6 +135,7 @@ struct kvm_vcpu_csr { > unsigned long hvip; > unsigned long vsatp; > unsigned long scounteren; > + u64 vstimecmp; No need for separate "vstimecmp" here instead you can re-use "next_cycles" of "struct kvm_vcpu_timer". > }; > > struct kvm_vcpu_arch { > diff --git a/arch/riscv/include/asm/kvm_vcpu_timer.h b/arch/riscv/include/asm/kvm_vcpu_timer.h > index 375281eb49e0..a24a265f3ccb 100644 > --- a/arch/riscv/include/asm/kvm_vcpu_timer.h > +++ b/arch/riscv/include/asm/kvm_vcpu_timer.h > @@ -28,6 +28,11 @@ struct kvm_vcpu_timer { > u64 next_cycles; > /* Underlying hrtimer instance */ > struct hrtimer hrt; > + > + /* Flag to check if sstc is enabled or not */ > + bool sstc_enabled; > + /* A function pointer to switch between stimecmp or hrtimer at runtime */ > + int (*timer_next_event)(struct kvm_vcpu *vcpu, u64 ncycles); > }; > > int kvm_riscv_vcpu_timer_next_event(struct kvm_vcpu *vcpu, u64 ncycles); > @@ -39,6 +44,7 @@ int kvm_riscv_vcpu_timer_init(struct kvm_vcpu *vcpu); > int kvm_riscv_vcpu_timer_deinit(struct kvm_vcpu *vcpu); > int kvm_riscv_vcpu_timer_reset(struct kvm_vcpu *vcpu); > void kvm_riscv_vcpu_timer_restore(struct kvm_vcpu *vcpu); > +void kvm_riscv_vcpu_timer_save(struct kvm_vcpu *vcpu); > int kvm_riscv_guest_timer_init(struct kvm *kvm); > - > +bool kvm_riscv_vcpu_timer_pending(struct kvm_vcpu *vcpu); > #endif > diff --git a/arch/riscv/include/uapi/asm/kvm.h b/arch/riscv/include/uapi/asm/kvm.h > index 92bd469e2ba6..d2f02ba1947a 100644 > --- a/arch/riscv/include/uapi/asm/kvm.h > +++ b/arch/riscv/include/uapi/asm/kvm.h > @@ -96,6 +96,7 @@ enum KVM_RISCV_ISA_EXT_ID { > KVM_RISCV_ISA_EXT_H, > KVM_RISCV_ISA_EXT_I, > KVM_RISCV_ISA_EXT_M, > + KVM_RISCV_ISA_EXT_SSTC, > KVM_RISCV_ISA_EXT_MAX, > }; > > diff --git a/arch/riscv/kvm/main.c b/arch/riscv/kvm/main.c > index 2e5ca43c8c49..83c4db7fc35f 100644 > --- a/arch/riscv/kvm/main.c > +++ b/arch/riscv/kvm/main.c > @@ -32,7 +32,7 @@ int kvm_arch_hardware_setup(void *opaque) > > int kvm_arch_hardware_enable(void) > { > - unsigned long hideleg, hedeleg; > + unsigned long hideleg, hedeleg, henvcfg; > > hedeleg = 0; > hedeleg |= (1UL << EXC_INST_MISALIGNED); > @@ -51,6 +51,16 @@ int kvm_arch_hardware_enable(void) > > csr_write(CSR_HCOUNTEREN, -1UL); > > + if (riscv_isa_extension_available(NULL, SSTC)) { > +#ifdef CONFIG_64BIT > + henvcfg = csr_read(CSR_HENVCFG); > + csr_write(CSR_HENVCFG, henvcfg | 1UL<<HENVCFG_STCE); > +#else > + henvcfg = csr_read(CSR_HENVCFGH); > + csr_write(CSR_HENVCFGH, henvcfg | 1UL<<HENVCFGH_STCE); > +#endif > + } > + > csr_write(CSR_HVIP, 0); > > return 0; > diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c > index 93492eb292fd..da1559725b03 100644 > --- a/arch/riscv/kvm/vcpu.c > +++ b/arch/riscv/kvm/vcpu.c > @@ -143,7 +143,7 @@ void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu) > > int kvm_cpu_has_pending_timer(struct kvm_vcpu *vcpu) > { > - return kvm_riscv_vcpu_has_interrupts(vcpu, 1UL << IRQ_VS_TIMER); > + return kvm_riscv_vcpu_timer_pending(vcpu); > } > > void kvm_arch_vcpu_blocking(struct kvm_vcpu *vcpu) > @@ -374,6 +374,7 @@ static unsigned long kvm_isa_ext_arr[] = { > RISCV_ISA_EXT_h, > RISCV_ISA_EXT_i, > RISCV_ISA_EXT_m, > + RISCV_ISA_EXT_SSTC, > }; > > static int kvm_riscv_vcpu_get_reg_isa_ext(struct kvm_vcpu *vcpu, > @@ -754,6 +755,8 @@ void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu) > vcpu->arch.isa); > kvm_riscv_vcpu_host_fp_restore(&vcpu->arch.host_context); > > + kvm_riscv_vcpu_timer_save(vcpu); > + > csr->vsstatus = csr_read(CSR_VSSTATUS); > csr->vsie = csr_read(CSR_VSIE); > csr->vstvec = csr_read(CSR_VSTVEC); > diff --git a/arch/riscv/kvm/vcpu_timer.c b/arch/riscv/kvm/vcpu_timer.c > index 5c4c37ff2d48..d226a931de92 100644 > --- a/arch/riscv/kvm/vcpu_timer.c > +++ b/arch/riscv/kvm/vcpu_timer.c > @@ -69,7 +69,18 @@ static int kvm_riscv_vcpu_timer_cancel(struct kvm_vcpu_timer *t) > return 0; > } > > -int kvm_riscv_vcpu_timer_next_event(struct kvm_vcpu *vcpu, u64 ncycles) > +static int kvm_riscv_vcpu_update_vstimecmp(struct kvm_vcpu *vcpu, u64 ncycles) > +{ > +#if __riscv_xlen == 32 > + csr_write(CSR_VSTIMECMP, ncycles & 0xFFFFFFFF); > + csr_write(CSR_VSTIMECMPH, ncycles >> 32); > +#else > + csr_write(CSR_VSTIMECMP, ncycles); > +#endif > + return 0; > +} > + > +static int kvm_riscv_vcpu_update_hrtimer(struct kvm_vcpu *vcpu, u64 ncycles) > { > struct kvm_vcpu_timer *t = &vcpu->arch.timer; > struct kvm_guest_timer *gt = &vcpu->kvm->arch.timer; > @@ -88,6 +99,68 @@ int kvm_riscv_vcpu_timer_next_event(struct kvm_vcpu *vcpu, u64 ncycles) > return 0; > } > > +int kvm_riscv_vcpu_timer_next_event(struct kvm_vcpu *vcpu, u64 ncycles) > +{ > + struct kvm_vcpu_timer *t = &vcpu->arch.timer; > + > + return t->timer_next_event(vcpu, ncycles); > +} > + > +static enum hrtimer_restart kvm_riscv_vcpu_vstimer_expired(struct hrtimer *h) > +{ > + u64 delta_ns; > + struct kvm_vcpu_timer *t = container_of(h, struct kvm_vcpu_timer, hrt); > + struct kvm_vcpu *vcpu = container_of(t, struct kvm_vcpu, arch.timer); > + struct kvm_guest_timer *gt = &vcpu->kvm->arch.timer; > + > + if (kvm_riscv_current_cycles(gt) < t->next_cycles) { > + delta_ns = kvm_riscv_delta_cycles2ns(t->next_cycles, gt, t); > + hrtimer_forward_now(&t->hrt, ktime_set(0, delta_ns)); > + return HRTIMER_RESTART; > + } > + > + t->next_set = false; > + kvm_vcpu_kick(vcpu); > + > + return HRTIMER_NORESTART; > +} > + > +bool kvm_riscv_vcpu_timer_pending(struct kvm_vcpu *vcpu) > +{ > + struct kvm_vcpu_timer *t = &vcpu->arch.timer; > + struct kvm_guest_timer *gt = &vcpu->kvm->arch.timer; > + u64 vstimecmp_val = vcpu->arch.guest_csr.vstimecmp; > + > + if (!kvm_riscv_delta_cycles2ns(vstimecmp_val, gt, t) || > + kvm_riscv_vcpu_has_interrupts(vcpu, 1UL << IRQ_VS_TIMER)) > + return true; > + else > + return false; > +} > + > +static void kvm_riscv_vcpu_timer_blocking(struct kvm_vcpu *vcpu) > +{ > + struct kvm_vcpu_timer *t = &vcpu->arch.timer; > + struct kvm_guest_timer *gt = &vcpu->kvm->arch.timer; > + u64 delta_ns; > + u64 vstimecmp_val = vcpu->arch.guest_csr.vstimecmp; Define delta_ns is same line as vstimecmp_val > + > + if (!t->init_done) > + return; > + > + delta_ns = kvm_riscv_delta_cycles2ns(vstimecmp_val, gt, t); > + if (delta_ns) { > + t->next_cycles = vstimecmp_val; > + hrtimer_start(&t->hrt, ktime_set(0, delta_ns), HRTIMER_MODE_REL); > + t->next_set = true; > + } > +} > + > +static void kvm_riscv_vcpu_timer_unblocking(struct kvm_vcpu *vcpu) > +{ > + kvm_riscv_vcpu_timer_cancel(&vcpu->arch.timer); > +} > + > int kvm_riscv_vcpu_get_reg_timer(struct kvm_vcpu *vcpu, > const struct kvm_one_reg *reg) > { > @@ -180,10 +253,20 @@ int kvm_riscv_vcpu_timer_init(struct kvm_vcpu *vcpu) > return -EINVAL; > > hrtimer_init(&t->hrt, CLOCK_MONOTONIC, HRTIMER_MODE_REL); > - t->hrt.function = kvm_riscv_vcpu_hrtimer_expired; > t->init_done = true; > t->next_set = false; > > + /* Enable sstc for every vcpu if available in hardware */ > + if (riscv_isa_extension_available(NULL, SSTC)) { > + t->sstc_enabled = true; > + t->hrt.function = kvm_riscv_vcpu_vstimer_expired; > + t->timer_next_event = kvm_riscv_vcpu_update_vstimecmp; > + } else { > + t->sstc_enabled = false; > + t->hrt.function = kvm_riscv_vcpu_hrtimer_expired; > + t->timer_next_event = kvm_riscv_vcpu_update_hrtimer; > + } > + > return 0; > } > > @@ -202,7 +285,7 @@ int kvm_riscv_vcpu_timer_reset(struct kvm_vcpu *vcpu) Set "next_cycles" to -1ULL in kvm_riscv_vcpu_timer_reset() because if we have older kernel (which does not use Sstc) as Guest then it will get timer interrupt immediately after enabling sie.STIE. > return kvm_riscv_vcpu_timer_cancel(&vcpu->arch.timer); > } > > -void kvm_riscv_vcpu_timer_restore(struct kvm_vcpu *vcpu) > +static void kvm_riscv_vcpu_update_timedelta(struct kvm_vcpu *vcpu) > { > struct kvm_guest_timer *gt = &vcpu->kvm->arch.timer; > > @@ -214,6 +297,55 @@ void kvm_riscv_vcpu_timer_restore(struct kvm_vcpu *vcpu) > #endif > } > > +void kvm_riscv_vcpu_timer_restore(struct kvm_vcpu *vcpu) > +{ > + struct kvm_vcpu_csr *csr; > + struct kvm_vcpu_timer *t = &vcpu->arch.timer; > + > + kvm_riscv_vcpu_update_timedelta(vcpu); > + > + if (!t->sstc_enabled) > + return; > + > + csr = &vcpu->arch.guest_csr; > +#ifdef CONFIG_64BIT > + csr_write(CSR_VSTIMECMP, csr->vstimecmp); > +#else > + csr_write(CSR_VSTIMECMP, (u32)csr->vstimecmp); > + csr_write(CSR_VSTIMECMPH, (u32)(csr->vstimecmp >> 32)); > +#endif > + > + /* timer should be enabled for the remaining operations */ > + if (unlikely(!t->init_done)) > + return; > + > + kvm_riscv_vcpu_timer_unblocking(vcpu); > +} > + > +void kvm_riscv_vcpu_timer_save(struct kvm_vcpu *vcpu) > +{ > + struct kvm_vcpu_csr *csr; > + struct kvm_vcpu_timer *t = &vcpu->arch.timer; > + > + if (!t->sstc_enabled) > + return; > + > + csr = &vcpu->arch.guest_csr; > + t = &vcpu->arch.timer; > +#ifdef CONFIG_64BIT > + csr->vstimecmp = csr_read(CSR_VSTIMECMP); > +#else > + csr->vstimecmp = csr_read(CSR_VSTIMECMP); > + csr->vstimecmp |= (u64)csr_read(CSR_VSTIMECMPH) << 32; > +#endif > + /* timer should be enabled for the remaining operations */ > + if (unlikely(!t->init_done)) > + return; > + > + if (kvm_vcpu_is_blocking(vcpu)) > + kvm_riscv_vcpu_timer_blocking(vcpu); > +} > + > int kvm_riscv_guest_timer_init(struct kvm *kvm) > { > struct kvm_guest_timer *gt = &kvm->arch.timer; > -- > 2.25.1 > Regards, Anup