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SubjectRe: [PATCH] kvm: Fixes lack of KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2 enabled check
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On 12/01/21 10:29, Kunkun Jiang wrote:
> The KVM_CLEAR_DIRTY_LOG ioctl lacks the check whether the capability
> KVM_CAP_MANUAL_DIRTY_LOG_PROTECT is enabled or not. This may cause
> some problems if userspace calls the KVM_CLEAR_DIRTY_LOG ioctl, but
> dose't enable this capability. So we'd better to add it.
>
> Fixes: 2a31b9db15353 ("kvm: introduce manual dirty log reprotect")
> Signed-off-by: Kunkun Jiang <jiangkunkun@huawei.com>
> ---
> virt/kvm/kvm_main.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index fa9e3614d30e..8f5633d8a0e8 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -1602,6 +1602,9 @@ static int kvm_clear_dirty_log_protect(struct kvm *kvm,
> unsigned long *dirty_bitmap_buffer;
> bool flush;
>
> + if (!kvm->manual_dirty_log_protect)
> + return -EPERM;
> +
> /* Dirty ring tracking is exclusive to dirty log tracking */
> if (kvm->dirty_ring_size)
> return -ENXIO;

This is not a problem, KVM_CLEAR_DIRTY_LOG can always be used even if
KVM_CAP_MANUAL_DIRTY_LOG_PROTECT was not enabled. The meaning is the
same: clear the bits without returning them.

Paolo

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