Re: [PATCH RFC v2 6/6] KVM: introduce a new API for getting dirty bitmaps

Alexander Graf
2010-04-21T09:41:24Z

On 21.04.2010, at 10:29, Fernando Luis Vázquez Cao wrote:

> On 04/20/2010 08:03 PM, Takuya Yoshikawa wrote:
>> @@ -318,7 +318,7 @@ struct kvm_dirty_log {
>> __u32 padding1;
>> union {
>> void __user *dirty_bitmap; /* one bit per page */
>> - __u64 padding2;
>> + __u64 addr;
>
> This can break on x86_32 and x86_64-compat. addr is a long not a __u64.

So the high 32 bits are zero. Where's the problem?

>
>
>> + case KVM_SWITCH_DIRTY_LOG: {
>> + struct kvm_dirty_log log;
>> +
>> + r = -EFAULT;
>> + if (copy_from_user(&log, argp, sizeof log))
>> + goto out;
>> + r = kvm_vm_ioctl_switch_dirty_log(kvm, &log);
>> + if (r)
>> + goto out;
>> + r = -EFAULT;
>> + if (copy_to_user(argp, &log, sizeof log))
>> + goto out;
>> + r = 0;
>> + break;
>> + }
>
> In x86_64-compat mode we are handling 32bit user-space addresses
> so we need the compat counterpart of KVM_SWITCH_DIRTY_LOG too.

The compat code just forwards everything to the generic ioctls.

Alex