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([2001:b07:6468:f312:71a5:6e:f854:d744]) by smtp.gmail.com with ESMTPSA id y6sm2561699wrr.19.2019.11.21.02.02.56 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 21 Nov 2019 02:02:56 -0800 (PST) Subject: Re: [PATCH v7 1/9] Documentation: Introduce EPT based Subpage Protection and related ioctls To: Yang Weijiang , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, jmattson@google.com, sean.j.christopherson@intel.com Cc: yu.c.zhang@linux.intel.com, alazar@bitdefender.com, edwin.zhai@intel.com References: <20191119084949.15471-1-weijiang.yang@intel.com> <20191119084949.15471-2-weijiang.yang@intel.com> From: Paolo Bonzini Message-ID: Date: Thu, 21 Nov 2019 11:02:56 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20191119084949.15471-2-weijiang.yang@intel.com> Content-Language: en-US X-MC-Unique: V-yciQ2OPM6Cf3hAjiiFOA-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 19/11/19 09:49, Yang Weijiang wrote: > + > +#define SUBPAGE_MAX_BITMAP 64 Please rename this to KVM_SUBPAGE_MAX_PAGES > +struct kvm_subpage_info { > +=09__u64 gfn; /* the first page gfn of the contiguous pages */ > +=09__u64 npages; /* number of 4K pages */ This can be =09u32 npages; =09u32 flags; Check that the flags are 0, and fail the ioctl if they aren't. This will make it easy to extend the API in the future. > +=09__u32 access_map[SUBPAGE_MAX_BITMAP]; /* sub-page write-access bitmap= array */ > +}; Please make this access_map[0], since the number of entries actually depends on npages. Likewise, kvm_arch_vm_ioctl should read the header first, then allocate memory for the access_map and read into it. It's probably simpler if you make kvm_vm_ioctl_get_subpages/kvm_vm_ioctl_set_subpages take parameters like int kvm_vm_ioctl_get_subpages(struct kvm *kvm, u64 gfn, u32 npages, =09=09=09 u32 *access_map); int kvm_vm_ioctl_set_subpages(struct kvm *kvm, u64 gfn, u32 npages, =09=09=09 u32 *access_map); Thanks, Paolo