diff options
Diffstat (limited to 'arch/arm64/kvm/arch_timer.c')
| -rw-r--r-- | arch/arm64/kvm/arch_timer.c | 58 |
1 files changed, 55 insertions, 3 deletions
diff --git a/arch/arm64/kvm/arch_timer.c b/arch/arm64/kvm/arch_timer.c index e5951e6eaf23..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, @@ -519,7 +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); @@ -624,8 +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; @@ -821,6 +834,13 @@ 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. @@ -1450,6 +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; @@ -1518,6 +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: |