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([2001:b07:6468:f312:c8dd:75d4:99ab:290a]) by smtp.gmail.com with ESMTPSA id x4sm1192917edr.40.2021.01.12.02.20.57 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 12 Jan 2021 02:20:57 -0800 (PST) Subject: Re: [PATCH] kvm: Fixes lack of KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2 enabled check To: Kunkun Jiang , kvm@vger.kernel.org, linux-kernel@vger.kernel.org Cc: wanghaibin.wang@huawei.com, Keqian Zhu References: <20210112092942.2310-1-jiangkunkun@huawei.com> From: Paolo Bonzini Message-ID: <9dd32bc9-a35c-e43f-51f2-c0989cca4e66@redhat.com> Date: Tue, 12 Jan 2021 11:20:56 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.5.0 MIME-Version: 1.0 In-Reply-To: <20210112092942.2310-1-jiangkunkun@huawei.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org 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 > --- > 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