diff options
Diffstat (limited to 'arch/arm64/kvm/arch_timer.c')
| -rw-r--r-- | arch/arm64/kvm/arch_timer.c | 179 |
1 files changed, 159 insertions, 20 deletions
diff --git a/arch/arm64/kvm/arch_timer.c b/arch/arm64/kvm/arch_timer.c index 1215df590418..d3d243366536 100644 --- a/arch/arm64/kvm/arch_timer.c +++ b/arch/arm64/kvm/arch_timer.c @@ -30,6 +30,7 @@ static u32 host_vtimer_irq_flags; static u32 host_ptimer_irq_flags; static DEFINE_STATIC_KEY_FALSE(has_gic_active_state); +DEFINE_STATIC_KEY_FALSE(broken_cntvoff_key); static const u8 default_ppi[] = { [TIMER_PTIMER] = 30, @@ -101,21 +102,6 @@ u64 timer_get_cval(struct arch_timer_context *ctxt) } } -static u64 timer_get_offset(struct arch_timer_context *ctxt) -{ - u64 offset = 0; - - if (!ctxt) - return 0; - - if (ctxt->offset.vm_offset) - offset += *ctxt->offset.vm_offset; - if (ctxt->offset.vcpu_offset) - offset += *ctxt->offset.vcpu_offset; - - return offset; -} - static void timer_set_ctl(struct arch_timer_context *ctxt, u32 ctl) { struct kvm_vcpu *vcpu = ctxt->vcpu; @@ -441,11 +427,30 @@ void kvm_timer_update_run(struct kvm_vcpu *vcpu) regs->device_irq_level |= KVM_ARM_DEV_EL1_PTIMER; } +static void kvm_timer_update_status(struct arch_timer_context *ctx, bool level) +{ + /* + * Paper over NV2 brokenness by publishing the interrupt status + * bit. This still results in a poor quality of emulation (guest + * writes will have no effect until the next exit). + * + * But hey, it's fast, right? + */ + if (is_hyp_ctxt(ctx->vcpu) && + (ctx == vcpu_vtimer(ctx->vcpu) || ctx == vcpu_ptimer(ctx->vcpu))) { + unsigned long val = timer_get_ctl(ctx); + __assign_bit(__ffs(ARCH_TIMER_CTRL_IT_STAT), &val, level); + timer_set_ctl(ctx, val); + } +} + static void kvm_timer_update_irq(struct kvm_vcpu *vcpu, bool new_level, struct arch_timer_context *timer_ctx) { int ret; + kvm_timer_update_status(timer_ctx, new_level); + timer_ctx->irq.level = new_level; trace_kvm_timer_update_irq(vcpu->vcpu_id, timer_irq(timer_ctx), timer_ctx->irq.level); @@ -471,6 +476,8 @@ static void timer_emulate(struct arch_timer_context *ctx) return; } + kvm_timer_update_status(ctx, should_fire); + /* * If the timer can fire now, we don't need to have a soft timer * scheduled for the future. If the timer cannot fire at all, @@ -513,7 +520,12 @@ static void timer_save_state(struct arch_timer_context *ctx) case TIMER_VTIMER: case TIMER_HVTIMER: timer_set_ctl(ctx, read_sysreg_el0(SYS_CNTV_CTL)); - timer_set_cval(ctx, read_sysreg_el0(SYS_CNTV_CVAL)); + cval = read_sysreg_el0(SYS_CNTV_CVAL); + + if (has_broken_cntvoff()) + cval -= timer_get_offset(ctx); + + timer_set_cval(ctx, cval); /* Disable the timer */ write_sysreg_el0(0, SYS_CNTV_CTL); @@ -618,8 +630,15 @@ static void timer_restore_state(struct arch_timer_context *ctx) case TIMER_VTIMER: case TIMER_HVTIMER: - set_cntvoff(timer_get_offset(ctx)); - write_sysreg_el0(timer_get_cval(ctx), SYS_CNTV_CVAL); + cval = timer_get_cval(ctx); + offset = timer_get_offset(ctx); + if (has_broken_cntvoff()) { + set_cntvoff(0); + cval += offset; + } else { + set_cntvoff(offset); + } + write_sysreg_el0(cval, SYS_CNTV_CVAL); isb(); write_sysreg_el0(timer_get_ctl(ctx), SYS_CNTV_CTL); break; @@ -762,7 +781,7 @@ static void kvm_timer_vcpu_load_nested_switch(struct kvm_vcpu *vcpu, static void timer_set_traps(struct kvm_vcpu *vcpu, struct timer_map *map) { - bool tpt, tpc; + bool tvt, tpt, tvc, tpc, tvt02, tpt02; u64 clr, set; /* @@ -777,7 +796,29 @@ static void timer_set_traps(struct kvm_vcpu *vcpu, struct timer_map *map) * within this function, reality kicks in and we start adding * traps based on emulation requirements. */ - tpt = tpc = false; + tvt = tpt = tvc = tpc = false; + tvt02 = tpt02 = false; + + /* + * NV2 badly breaks the timer semantics by redirecting accesses to + * the EL1 timer state to memory, so let's call ECV to the rescue if + * available: we trap all CNT{P,V}_{CTL,CVAL,TVAL}_EL0 accesses. + * + * The treatment slightly varies depending whether we run a nVHE or + * VHE guest: nVHE will use the _EL0 registers directly, while VHE + * will use the _EL02 accessors. This translates in different trap + * bits. + * + * None of the trapping is required when running in non-HYP context, + * unless required by the L1 hypervisor settings once we advertise + * ECV+NV in the guest, or that we need trapping for other reasons. + */ + if (cpus_have_final_cap(ARM64_HAS_ECV) && is_hyp_ctxt(vcpu)) { + if (vcpu_el2_e2h_is_set(vcpu)) + tvt02 = tpt02 = true; + else + tvt = tpt = true; + } /* * We have two possibility to deal with a physical offset: @@ -793,9 +834,20 @@ static void timer_set_traps(struct kvm_vcpu *vcpu, struct timer_map *map) tpt = tpc = true; /* + * For the poor sods that could not correctly substract one value + * from another, trap the full virtual timer and counter. + */ + if (has_broken_cntvoff() && timer_get_offset(map->direct_vtimer)) + tvt = tvc = true; + + /* * Apply the enable bits that the guest hypervisor has requested for * its own guest. We can only add traps that wouldn't have been set * above. + * Implementation choices: we do not support NV when E2H=0 in the + * guest, and we don't support configuration where E2H is writable + * by the guest (either FEAT_VHE or FEAT_E2H0 is implemented, but + * not both). This simplifies the handling of the EL1NV* bits. */ if (vcpu_has_nv(vcpu) && !is_hyp_ctxt(vcpu)) { u64 val = __vcpu_sys_reg(vcpu, CNTHCTL_EL2); @@ -806,6 +858,9 @@ static void timer_set_traps(struct kvm_vcpu *vcpu, struct timer_map *map) tpt |= !(val & (CNTHCTL_EL1PCEN << 10)); tpc |= !(val & (CNTHCTL_EL1PCTEN << 10)); + + tpt02 |= (val & CNTHCTL_EL1NVPCT); + tvt02 |= (val & CNTHCTL_EL1NVVCT); } /* @@ -817,6 +872,10 @@ static void timer_set_traps(struct kvm_vcpu *vcpu, struct timer_map *map) assign_clear_set_bit(tpt, CNTHCTL_EL1PCEN << 10, set, clr); assign_clear_set_bit(tpc, CNTHCTL_EL1PCTEN << 10, set, clr); + assign_clear_set_bit(tvt, CNTHCTL_EL1TVT, clr, set); + assign_clear_set_bit(tvc, CNTHCTL_EL1TVCT, clr, set); + assign_clear_set_bit(tvt02, CNTHCTL_EL1NVVCT, clr, set); + assign_clear_set_bit(tpt02, CNTHCTL_EL1NVPCT, clr, set); /* This only happens on VHE, so use the CNTHCTL_EL2 accessor. */ sysreg_clear_set(cnthctl_el2, clr, set); @@ -905,6 +964,54 @@ void kvm_timer_vcpu_put(struct kvm_vcpu *vcpu) kvm_timer_blocking(vcpu); } +void kvm_timer_sync_nested(struct kvm_vcpu *vcpu) +{ + /* + * When NV2 is on, guest hypervisors have their EL1 timer register + * accesses redirected to the VNCR page. Any guest action taken on + * the timer is postponed until the next exit, leading to a very + * poor quality of emulation. + * + * This is an unmitigated disaster, only papered over by FEAT_ECV, + * which allows trapping of the timer registers even with NV2. + * Still, this is still worse than FEAT_NV on its own. Meh. + */ + if (!vcpu_el2_e2h_is_set(vcpu)) { + if (cpus_have_final_cap(ARM64_HAS_ECV)) + return; + + /* + * A non-VHE guest hypervisor doesn't have any direct access + * to its timers: the EL2 registers trap (and the HW is + * fully emulated), while the EL0 registers access memory + * despite the access being notionally direct. Boo. + * + * We update the hardware timer registers with the + * latest value written by the guest to the VNCR page + * and let the hardware take care of the rest. + */ + write_sysreg_el0(__vcpu_sys_reg(vcpu, CNTV_CTL_EL0), SYS_CNTV_CTL); + write_sysreg_el0(__vcpu_sys_reg(vcpu, CNTV_CVAL_EL0), SYS_CNTV_CVAL); + write_sysreg_el0(__vcpu_sys_reg(vcpu, CNTP_CTL_EL0), SYS_CNTP_CTL); + write_sysreg_el0(__vcpu_sys_reg(vcpu, CNTP_CVAL_EL0), SYS_CNTP_CVAL); + } else { + /* + * For a VHE guest hypervisor, the EL2 state is directly + * stored in the host EL1 timers, while the emulated EL0 + * state is stored in the VNCR page. The latter could have + * been updated behind our back, and we must reset the + * emulation of the timers. + */ + struct timer_map map; + get_timer_map(vcpu, &map); + + soft_timer_cancel(&map.emul_vtimer->hrtimer); + soft_timer_cancel(&map.emul_ptimer->hrtimer); + timer_emulate(map.emul_vtimer); + timer_emulate(map.emul_ptimer); + } +} + /* * With a userspace irqchip we have to check if the guest de-asserted the * timer and if so, unmask the timer irq signal on the host interrupt @@ -1363,6 +1470,37 @@ static int kvm_irq_init(struct arch_timer_kvm_info *info) return 0; } +static void kvm_timer_handle_errata(void) +{ + u64 mmfr0, mmfr1, mmfr4; + + /* + * CNTVOFF_EL2 is broken on some implementations. For those, we trap + * all virtual timer/counter accesses, requiring FEAT_ECV. + * + * However, a hypervisor supporting nesting is likely to mitigate the + * erratum at L0, and not require other levels to mitigate it (which + * would otherwise be a terrible performance sink due to trap + * amplification). + * + * Given that the affected HW implements both FEAT_VHE and FEAT_E2H0, + * and that NV is likely not to (because of limitations of the + * architecture), only enable the workaround when FEAT_VHE and + * FEAT_E2H0 are both detected. Time will tell if this actually holds. + */ + mmfr0 = read_sanitised_ftr_reg(SYS_ID_AA64MMFR0_EL1); + mmfr1 = read_sanitised_ftr_reg(SYS_ID_AA64MMFR1_EL1); + mmfr4 = read_sanitised_ftr_reg(SYS_ID_AA64MMFR4_EL1); + if (SYS_FIELD_GET(ID_AA64MMFR1_EL1, VH, mmfr1) && + !SYS_FIELD_GET(ID_AA64MMFR4_EL1, E2H0, mmfr4) && + SYS_FIELD_GET(ID_AA64MMFR0_EL1, ECV, mmfr0) && + (has_vhe() || has_hvhe()) && + cpus_have_final_cap(ARM64_WORKAROUND_QCOM_ORYON_CNTVOFF)) { + static_branch_enable(&broken_cntvoff_key); + kvm_info("Broken CNTVOFF_EL2, trapping virtual timer\n"); + } +} + int __init kvm_timer_hyp_init(bool has_gic) { struct arch_timer_kvm_info *info; @@ -1431,6 +1569,7 @@ int __init kvm_timer_hyp_init(bool has_gic) goto out_free_vtimer_irq; } + kvm_timer_handle_errata(); return 0; out_free_ptimer_irq: |