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Shutemov" Cc: Dave Hansen , Andy Lutomirski , Paolo Bonzini , Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , David Rientjes , Andrea Arcangeli , Kees Cook , Will Drewry , "Edgecombe, Rick P" , "Kleen, Andi" , Liran Alon , Mike Rapoport , x86@kernel.org, kvm@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, "Kirill A. Shutemov" Subject: Re: [RFCv2 11/16] KVM: Protected memory extension Message-ID: <20201020071701.GV2611@hirez.programming.kicks-ass.net> References: <20201020061859.18385-1-kirill.shutemov@linux.intel.com> <20201020061859.18385-12-kirill.shutemov@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201020061859.18385-12-kirill.shutemov@linux.intel.com> X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, Oct 20, 2020 at 09:18:54AM +0300, Kirill A. Shutemov wrote: > +int __kvm_protect_memory(unsigned long start, unsigned long end, bool protect) > +{ > + struct mm_struct *mm = current->mm; > + struct vm_area_struct *vma, *prev; > + int ret; > + > + if (mmap_write_lock_killable(mm)) > + return -EINTR; > + > + ret = -ENOMEM; > + vma = find_vma(current->mm, start); > + if (!vma) > + goto out; > + > + ret = -EINVAL; > + if (vma->vm_start > start) > + goto out; > + > + if (start > vma->vm_start) > + prev = vma; > + else > + prev = vma->vm_prev; > + > + ret = 0; > + while (true) { > + unsigned long newflags, tmp; > + > + tmp = vma->vm_end; > + if (tmp > end) > + tmp = end; > + > + newflags = vma->vm_flags; > + if (protect) > + newflags |= VM_KVM_PROTECTED; > + else > + newflags &= ~VM_KVM_PROTECTED; > + > + /* The VMA has been handled as part of other memslot */ > + if (newflags == vma->vm_flags) > + goto next; > + > + ret = mprotect_fixup(vma, &prev, start, tmp, newflags); > + if (ret) > + goto out; > + > +next: > + start = tmp; > + if (start < prev->vm_end) > + start = prev->vm_end; > + > + if (start >= end) > + goto out; > + > + vma = prev->vm_next; > + if (!vma || vma->vm_start != start) { > + ret = -ENOMEM; > + goto out; > + } > + } > +out: > + mmap_write_unlock(mm); > + return ret; > +} > +EXPORT_SYMBOL_GPL(__kvm_protect_memory); Since migration will be disabled after this; should the above not (at the very least) force compaction before proceeding to lock the pages in?