From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id F3F07C433DF for ; Tue, 26 May 2020 06:16:03 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id B0ECC2100A for ; Tue, 26 May 2020 06:16:03 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="kjXWSk+y" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B0ECC2100A Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 4747D8007D; Tue, 26 May 2020 02:16:03 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 425C180061; Tue, 26 May 2020 02:16:03 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 315398007D; Tue, 26 May 2020 02:16:03 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0177.hostedemail.com [216.40.44.177]) by kanga.kvack.org (Postfix) with ESMTP id 19EF980061 for ; Tue, 26 May 2020 02:16:03 -0400 (EDT) Received: from smtpin10.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id BF7B4180AD806 for ; Tue, 26 May 2020 06:16:02 +0000 (UTC) X-FDA: 76857859764.10.space58_6ef0c8b311720 X-HE-Tag: space58_6ef0c8b311720 X-Filterd-Recvd-Size: 7413 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf14.hostedemail.com (Postfix) with ESMTP for ; Tue, 26 May 2020 06:16:02 +0000 (UTC) Received: from kernel.org (unknown [87.70.212.59]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 5545C207CB; Tue, 26 May 2020 06:15:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1590473761; bh=OxSFsKg1PycFHLkeCq0fALukk6xQ/Qv8MqdKEfRKfi8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=kjXWSk+yDAClp/K1lADNvHh0cBh0iJQ49Oq8CqmlRNsbbevhKuqwgLoJPfXLHwUuU VAuZWwmgY8mKawGezWHkpFgAcMyP0QXZ+1ffbhqAigOXinrM9aKxaAL5GSkEDdMEy9 fRmF7ahduAJGkjY7Bf6bAjCi6VcdaxX2doQzDisQ= Date: Tue, 26 May 2020 09:15:52 +0300 From: Mike Rapoport To: "Kirill A. Shutemov" 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: <20200526061552.GD13247@kernel.org> References: <20200522125214.31348-1-kirill.shutemov@linux.intel.com> <20200522125214.31348-8-kirill.shutemov@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200522125214.31348-8-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 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 :) > #ifndef VM_GROWSUP > # define VM_GROWSUP VM_NONE > #endif > @@ -646,6 +648,11 @@ static inline bool vma_is_accessible(struct vm_area_struct *vma) > return vma->vm_flags & VM_ACCESS_FLAGS; > } > > +static inline bool vma_is_kvm_protected(struct vm_area_struct *vma) Ditto > +{ > + return vma->vm_flags & VM_KVM_PROTECTED; > +} > + > #ifdef CONFIG_SHMEM > /* > * The vma_is_shmem is not inline because it is used only by slow > @@ -2773,6 +2780,7 @@ struct page *follow_page(struct vm_area_struct *vma, unsigned long address, > #define FOLL_LONGTERM 0x10000 /* mapping lifetime is indefinite: see below */ > #define FOLL_SPLIT_PMD 0x20000 /* split huge pmd before returning */ > #define FOLL_PIN 0x40000 /* pages must be released via unpin_user_page */ > +#define FOLL_KVM 0x80000 /* access to VM_KVM_PROTECTED VMAs */ Maybe FOLL_DM 0x80000 /* access memory dropped from the direct map */ > /* > * FOLL_PIN and FOLL_LONGTERM may be used in various combinations with each > diff --git a/mm/gup.c b/mm/gup.c > index 87a6a59fe667..bd7b9484b35a 100644 > --- a/mm/gup.c > +++ b/mm/gup.c ... > 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()? > + > return arch_filter_pgprot(ret); > } > EXPORT_SYMBOL(vm_get_page_prot); > diff --git a/virt/kvm/async_pf.c b/virt/kvm/async_pf.c > index 15e5b037f92d..7663e962510a 100644 > --- a/virt/kvm/async_pf.c > +++ b/virt/kvm/async_pf.c > @@ -60,8 +60,8 @@ static void async_pf_execute(struct work_struct *work) > * access remotely. > */ > down_read(&mm->mmap_sem); > - get_user_pages_remote(NULL, mm, addr, 1, FOLL_WRITE, NULL, NULL, > - &locked); > + get_user_pages_remote(NULL, mm, addr, 1, FOLL_WRITE | FOLL_KVM, NULL, > + NULL, &locked); > if (locked) > up_read(&mm->mmap_sem); > > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > index 033471f71dae..530af95efdf3 100644 > --- a/virt/kvm/kvm_main.c > +++ b/virt/kvm/kvm_main.c > @@ -1727,7 +1727,7 @@ unsigned long kvm_vcpu_gfn_to_hva_prot(struct kvm_vcpu *vcpu, gfn_t gfn, bool *w > > static inline int check_user_page_hwpoison(unsigned long addr) > { > - int rc, flags = FOLL_HWPOISON | FOLL_WRITE; > + int rc, flags = FOLL_HWPOISON | FOLL_WRITE | FOLL_KVM; > > rc = get_user_pages(addr, 1, flags, NULL, NULL); > return rc == -EHWPOISON; > @@ -1771,7 +1771,7 @@ static bool hva_to_pfn_fast(unsigned long addr, bool write_fault, > static int hva_to_pfn_slow(unsigned long addr, bool *async, bool write_fault, > bool *writable, kvm_pfn_t *pfn) > { > - unsigned int flags = FOLL_HWPOISON; > + unsigned int flags = FOLL_HWPOISON | FOLL_KVM; > struct page *page; > int npages = 0; > > @@ -2255,7 +2255,7 @@ int copy_from_guest(void *data, unsigned long hva, int len) > int npages, seg; > > while ((seg = next_segment(len, offset)) != 0) { > - npages = get_user_pages_unlocked(hva, 1, &page, 0); > + npages = get_user_pages_unlocked(hva, 1, &page, FOLL_KVM); > if (npages != 1) > return -EFAULT; > memcpy(data, page_address(page) + offset, seg); > @@ -2275,7 +2275,8 @@ int copy_to_guest(unsigned long hva, const void *data, int len) > int npages, seg; > > while ((seg = next_segment(len, offset)) != 0) { > - npages = get_user_pages_unlocked(hva, 1, &page, FOLL_WRITE); > + npages = get_user_pages_unlocked(hva, 1, &page, > + FOLL_WRITE | FOLL_KVM); > if (npages != 1) > return -EFAULT; > memcpy(page_address(page) + offset, data, seg); > -- > 2.26.2 > > -- Sincerely yours, Mike.