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Shutemov" To: Mike Rapoport Cc: Dave Hansen , Andy Lutomirski , Peter Zijlstra , 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" , x86@kernel.org, kvm@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, "Kirill A. Shutemov" Subject: Re: [RFC 07/16] KVM: mm: Introduce VM_KVM_PROTECTED Message-ID: <20200526220155.34xmakrh7ipqynht@box> References: <20200522125214.31348-1-kirill.shutemov@linux.intel.com> <20200522125214.31348-8-kirill.shutemov@linux.intel.com> <20200526061552.GD13247@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200526061552.GD13247@kernel.org> 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, May 26, 2020 at 09:15:52AM +0300, Mike Rapoport wrote: > On Fri, May 22, 2020 at 03:52:05PM +0300, Kirill A. Shutemov wrote: > > The new VMA flag that indicate a VMA that is not accessible to userspace > > but usable by kernel with GUP if FOLL_KVM is specified. > > > > The FOLL_KVM is only used in the KVM code. The code has to know how to > > deal with such pages. > > > > Signed-off-by: Kirill A. Shutemov > > --- > > include/linux/mm.h | 8 ++++++++ > > mm/gup.c | 20 ++++++++++++++++---- > > mm/huge_memory.c | 20 ++++++++++++++++---- > > mm/memory.c | 3 +++ > > mm/mmap.c | 3 +++ > > virt/kvm/async_pf.c | 4 ++-- > > virt/kvm/kvm_main.c | 9 +++++---- > > 7 files changed, 53 insertions(+), 14 deletions(-) > > > > diff --git a/include/linux/mm.h b/include/linux/mm.h > > index e1882eec1752..4f7195365cc0 100644 > > --- a/include/linux/mm.h > > +++ b/include/linux/mm.h > > @@ -329,6 +329,8 @@ extern unsigned int kobjsize(const void *objp); > > # define VM_MAPPED_COPY VM_ARCH_1 /* T if mapped copy of data (nommu mmap) */ > > #endif > > > > +#define VM_KVM_PROTECTED 0 > > With all the ideas about removing pages from the direct mapi floating > around I wouldn't limit this to KVM. > > VM_NOT_IN_DIRECT_MAP would describe such areas better, but I realise > it's very far from perfect and nothing better does not comes to mind :) I don't like VM_NOT_IN_DIRECT_MAP. It's not only about direct mapping, but about userspace mapping as well. For the same reason other naming proposals don't fit as well. > > diff --git a/mm/mmap.c b/mm/mmap.c > > index f609e9ec4a25..d56c3f6efc99 100644 > > --- a/mm/mmap.c > > +++ b/mm/mmap.c > > @@ -112,6 +112,9 @@ pgprot_t vm_get_page_prot(unsigned long vm_flags) > > (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]) | > > pgprot_val(arch_vm_get_page_prot(vm_flags))); > > > > + if (vm_flags & VM_KVM_PROTECTED) > > + ret = PAGE_NONE; > > Nit: vma_is_kvm_protected()? Which VMA? :P -- Kirill A. Shutemov