diff options
Diffstat (limited to 'arch/arm/kvm/arm.c')
| -rw-r--r-- | arch/arm/kvm/arm.c | 34 |
1 files changed, 34 insertions, 0 deletions
diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c index 2d6d91001062..1434410e7f46 100644 --- a/arch/arm/kvm/arm.c +++ b/arch/arm/kvm/arm.c @@ -787,9 +787,43 @@ long kvm_arch_vcpu_ioctl(struct file *filp, } } +/** + * kvm_vm_ioctl_get_dirty_log - get and clear the log of dirty pages in a slot + * @kvm: kvm instance + * @log: slot id and address to which we copy the log + * + * Steps 1-4 below provide general overview of dirty page logging. See + * kvm_get_dirty_log_protect() function description for additional details. + * + * We call kvm_get_dirty_log_protect() to handle steps 1-3, upon return we + * always flush the TLB (step 4) even if previous step failed and the dirty + * bitmap may be corrupt. Regardless of previous outcome the KVM logging API + * does not preclude user space subsequent dirty log read. Flushing TLB ensures + * writes will be marked dirty for next log read. + * + * 1. Take a snapshot of the bit and clear it if needed. + * 2. Write protect the corresponding page. + * 3. Copy the snapshot to the userspace. + * 4. Flush TLB's if needed. + */ int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, struct kvm_dirty_log *log) { +#ifdef CONFIG_ARM + bool is_dirty = false; + int r; + + mutex_lock(&kvm->slots_lock); + + r = kvm_get_dirty_log_protect(kvm, log, &is_dirty); + + if (is_dirty) + kvm_flush_remote_tlbs(kvm); + + mutex_unlock(&kvm->slots_lock); + return r; +#else /* arm64 */ return -EINVAL; +#endif } static int kvm_vm_ioctl_set_device_addr(struct kvm *kvm, |