From: Andrew Jones <drjones@xxxxxxxxxx> When updating the stolen time we should always read the current stolen time from the user provided memory, not from a kernel cache. If we use a cache then we'll end up resetting stolen time to zero on the first update after migration. Signed-off-by: Andrew Jones <drjones@xxxxxxxxxx> Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx> Link: https://lore.kernel.org/r/20200804170604.42662-5-drjones@xxxxxxxxxx --- arch/arm64/include/asm/kvm_host.h | 1 - arch/arm64/kvm/pvtime.c | 23 +++++++++-------------- include/linux/kvm_host.h | 20 ++++++++++++++++++++ 3 files changed, 29 insertions(+), 15 deletions(-) diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index 65568b23868a..dd9c3b25aa1e 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -368,7 +368,6 @@ struct kvm_vcpu_arch { /* Guest PV state */ struct { - u64 steal; u64 last_steal; gpa_t base; } steal; diff --git a/arch/arm64/kvm/pvtime.c b/arch/arm64/kvm/pvtime.c index 241ded7ee0ad..75234321d896 100644 --- a/arch/arm64/kvm/pvtime.c +++ b/arch/arm64/kvm/pvtime.c @@ -13,26 +13,22 @@ void kvm_update_stolen_time(struct kvm_vcpu *vcpu) { struct kvm *kvm = vcpu->kvm; + u64 base = vcpu->arch.steal.base; u64 last_steal = vcpu->arch.steal.last_steal; - u64 steal; - __le64 steal_le; - u64 offset; + u64 offset = offsetof(struct pvclock_vcpu_stolen_time, stolen_time); + u64 steal = 0; int idx; - u64 base = vcpu->arch.steal.base; if (base == GPA_INVALID) return; - /* Let's do the local bookkeeping */ - steal = vcpu->arch.steal.steal; - vcpu->arch.steal.last_steal = READ_ONCE(current->sched_info.run_delay); - steal += vcpu->arch.steal.last_steal - last_steal; - vcpu->arch.steal.steal = steal; - - steal_le = cpu_to_le64(steal); idx = srcu_read_lock(&kvm->srcu); - offset = offsetof(struct pvclock_vcpu_stolen_time, stolen_time); - kvm_put_guest(kvm, base + offset, steal_le); + if (!kvm_get_guest(kvm, base + offset, steal)) { + steal = le64_to_cpu(steal); + vcpu->arch.steal.last_steal = READ_ONCE(current->sched_info.run_delay); + steal += vcpu->arch.steal.last_steal - last_steal; + kvm_put_guest(kvm, base + offset, cpu_to_le64(steal)); + } srcu_read_unlock(&kvm->srcu, idx); } @@ -66,7 +62,6 @@ gpa_t kvm_init_stolen_time(struct kvm_vcpu *vcpu) * Start counting stolen time from the time the guest requests * the feature enabled. */ - vcpu->arch.steal.steal = 0; vcpu->arch.steal.last_steal = current->sched_info.run_delay; idx = srcu_read_lock(&kvm->srcu); diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 84371fb06209..05e3c2fb3ef7 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -749,6 +749,26 @@ int kvm_write_guest_offset_cached(struct kvm *kvm, struct gfn_to_hva_cache *ghc, int kvm_gfn_to_hva_cache_init(struct kvm *kvm, struct gfn_to_hva_cache *ghc, gpa_t gpa, unsigned long len); +#define __kvm_get_guest(kvm, gfn, offset, v) \ +({ \ + unsigned long __addr = gfn_to_hva(kvm, gfn); \ + typeof(v) __user *__uaddr = (typeof(__uaddr))(__addr + offset); \ + int __ret = -EFAULT; \ + \ + if (!kvm_is_error_hva(__addr)) \ + __ret = get_user(v, __uaddr); \ + __ret; \ +}) + +#define kvm_get_guest(kvm, gpa, v) \ +({ \ + gpa_t __gpa = gpa; \ + struct kvm *__kvm = kvm; \ + \ + __kvm_get_guest(__kvm, __gpa >> PAGE_SHIFT, \ + offset_in_page(__gpa), v); \ +}) + #define __kvm_put_guest(kvm, gfn, offset, v) \ ({ \ unsigned long __addr = gfn_to_hva(kvm, gfn); \ -- 2.27.0 _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
