From: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com> virt inclusion category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/IBMHO0 CVE: NA -------------------------------- Introduce kvm_arm_pinned_vmid_get() and kvm_arm_pinned_vmid_put(), to pin a VMID associated with a KVM instance. This will guarantee that VMID remains the same after a rollover. This is in preparation of introducing support in the SMMUv3 driver to use the KVM VMID for S2 stage configuration in nested mode. Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com> Signed-off-by: Kunkun Jiang <jiangkunkun@huawei.com> Signed-off-by: lishusen <lishusen2@huawei.com> --- arch/arm64/include/asm/kvm_host.h | 3 ++ arch/arm64/kvm/vmid.c | 84 ++++++++++++++++++++++++++++++- 2 files changed, 86 insertions(+), 1 deletion(-) diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index 81898bb87c5e..35b56d38bd96 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -143,6 +143,7 @@ int topup_hyp_memcache(struct kvm_hyp_memcache *mc, unsigned long min_pages); struct kvm_vmid { atomic64_t id; + refcount_t pinned; }; struct kvm_s2_mmu { @@ -1106,6 +1107,8 @@ int __init kvm_arm_vmid_alloc_init(void); void __init kvm_arm_vmid_alloc_free(void); void kvm_arm_vmid_update(struct kvm_vmid *kvm_vmid); void kvm_arm_vmid_clear_active(void); +unsigned long kvm_arm_pinned_vmid_get(struct kvm_vmid *kvm_vmid); +void kvm_arm_pinned_vmid_put(struct kvm_vmid *kvm_vmid); static inline void kvm_arm_pvtime_vcpu_init(struct kvm_vcpu_arch *vcpu_arch) { diff --git a/arch/arm64/kvm/vmid.c b/arch/arm64/kvm/vmid.c index 7fe8ba1a2851..cbc9c5f25033 100644 --- a/arch/arm64/kvm/vmid.c +++ b/arch/arm64/kvm/vmid.c @@ -25,6 +25,10 @@ static unsigned long *vmid_map; static DEFINE_PER_CPU(atomic64_t, active_vmids); static DEFINE_PER_CPU(u64, reserved_vmids); +static unsigned long max_pinned_vmids; +static unsigned long nr_pinned_vmids; +static unsigned long *pinned_vmid_map; + #define VMID_MASK (~GENMASK(kvm_arm_vmid_bits - 1, 0)) #define VMID_FIRST_VERSION (1UL << kvm_arm_vmid_bits) @@ -47,7 +51,10 @@ static void flush_context(void) int cpu; u64 vmid; - bitmap_zero(vmid_map, NUM_USER_VMIDS); + if (pinned_vmid_map) + bitmap_copy(vmid_map, pinned_vmid_map, NUM_USER_VMIDS); + else + bitmap_zero(vmid_map, NUM_USER_VMIDS); for_each_possible_cpu(cpu) { vmid = atomic64_xchg_relaxed(&per_cpu(active_vmids, cpu), 0); @@ -103,6 +110,14 @@ static u64 new_vmid(struct kvm_vmid *kvm_vmid) return newvmid; } + /* + * If it is pinned, we can keep using it. Note that reserved + * takes priority, because even if it is also pinned, we need to + * update the generation into the reserved_vmids. + */ + if (refcount_read(&kvm_vmid->pinned)) + return newvmid; + if (!__test_and_set_bit(vmid2idx(vmid), vmid_map)) { atomic64_set(&kvm_vmid->id, newvmid); return newvmid; @@ -169,6 +184,63 @@ void kvm_arm_vmid_update(struct kvm_vmid *kvm_vmid) raw_spin_unlock_irqrestore(&cpu_vmid_lock, flags); } +unsigned long kvm_arm_pinned_vmid_get(struct kvm_vmid *kvm_vmid) +{ + unsigned long flags; + u64 vmid; + + if (!pinned_vmid_map) + return 0; + + raw_spin_lock_irqsave(&cpu_vmid_lock, flags); + + vmid = atomic64_read(&kvm_vmid->id); + + if (refcount_inc_not_zero(&kvm_vmid->pinned)) + goto out_unlock; + + if (nr_pinned_vmids >= max_pinned_vmids) { + vmid = 0; + goto out_unlock; + } + + /* + * If we went through one or more rollover since that VMID was + * used, make sure it is still valid, or generate a new one. + */ + if (!vmid_gen_match(vmid)) + vmid = new_vmid(kvm_vmid); + + nr_pinned_vmids++; + __set_bit(vmid2idx(vmid), pinned_vmid_map); + refcount_set(&kvm_vmid->pinned, 1); + +out_unlock: + raw_spin_unlock_irqrestore(&cpu_vmid_lock, flags); + + vmid &= ~VMID_MASK; + + return vmid; +} + +void kvm_arm_pinned_vmid_put(struct kvm_vmid *kvm_vmid) +{ + unsigned long flags; + u64 vmid = atomic64_read(&kvm_vmid->id); + + if (!pinned_vmid_map) + return; + + raw_spin_lock_irqsave(&cpu_vmid_lock, flags); + + if (refcount_dec_and_test(&kvm_vmid->pinned)) { + __clear_bit(vmid2idx(vmid), pinned_vmid_map); + nr_pinned_vmids--; + } + + raw_spin_unlock_irqrestore(&cpu_vmid_lock, flags); +} + /* * Initialize the VMID allocator */ @@ -186,10 +258,20 @@ int __init kvm_arm_vmid_alloc_init(void) if (!vmid_map) return -ENOMEM; + pinned_vmid_map = bitmap_zalloc(NUM_USER_VMIDS, GFP_KERNEL); + nr_pinned_vmids = 0; + + /* + * Ensure we have at least one emty slot available after rollover + * and maximum number of VMIDs are pinned. VMID#0 is reserved. + */ + max_pinned_vmids = NUM_USER_VMIDS - num_possible_cpus() - 2; + return 0; } void __init kvm_arm_vmid_alloc_free(void) { + bitmap_free(pinned_vmid_map); bitmap_free(vmid_map); } -- 2.33.0