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=-11.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 9FDEEC4363A for ; Tue, 20 Oct 2020 17:29:51 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id E05F22222D for ; Tue, 20 Oct 2020 17:29:50 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E05F22222D Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 23F596B005C; Tue, 20 Oct 2020 13:29:50 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 214E76B0062; Tue, 20 Oct 2020 13:29:50 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 151436B0068; Tue, 20 Oct 2020 13:29:50 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0153.hostedemail.com [216.40.44.153]) by kanga.kvack.org (Postfix) with ESMTP id DC2E16B005C for ; Tue, 20 Oct 2020 13:29:49 -0400 (EDT) Received: from smtpin06.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 77AC71EE6 for ; Tue, 20 Oct 2020 17:29:49 +0000 (UTC) X-FDA: 77392991298.06.stove68_1b14f5027241 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin06.hostedemail.com (Postfix) with ESMTP id 6928910286B16 for ; Tue, 20 Oct 2020 17:29:49 +0000 (UTC) X-HE-Tag: stove68_1b14f5027241 X-Filterd-Recvd-Size: 9828 Received: from mga04.intel.com (mga04.intel.com [192.55.52.120]) by imf09.hostedemail.com (Postfix) with ESMTP for ; Tue, 20 Oct 2020 17:29:47 +0000 (UTC) IronPort-SDR: qy+eNVHn5Rzc+cDwSapEl5iz3j7Q9HMNqkK4rfcEy5OlIcc9+wNi60geHa00o9Lh2rLHkBhTwV 4+y7/rWRjmiQ== X-IronPort-AV: E=McAfee;i="6000,8403,9780"; a="164641187" X-IronPort-AV: E=Sophos;i="5.77,398,1596524400"; d="scan'208";a="164641187" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga005.jf.intel.com ([10.7.209.41]) by fmsmga104.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Oct 2020 10:29:45 -0700 IronPort-SDR: SqScpvwPfGLx6n+SNpJqcFwJ5diV55xjIwuTyl5Nj4lHyQ6jjy/9E+bKyXG/2D4j+S5hy1npEo SpapDIzAUVXw== X-IronPort-AV: E=Sophos;i="5.77,398,1596524400"; d="scan'208";a="533155421" Received: from iweiny-desk2.sc.intel.com (HELO localhost) ([10.3.52.147]) by orsmga005-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Oct 2020 10:29:44 -0700 Date: Tue, 20 Oct 2020 10:29:44 -0700 From: Ira Weiny 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" , 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 08/16] KVM: Use GUP instead of copy_from/to_user() to access guest memory Message-ID: <20201020172944.GA165907@iweiny-DESK2.sc.intel.com> References: <20201020061859.18385-1-kirill.shutemov@linux.intel.com> <20201020061859.18385-9-kirill.shutemov@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201020061859.18385-9-kirill.shutemov@linux.intel.com> User-Agent: Mutt/1.11.1 (2018-12-01) 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 09:18:51AM +0300, Kirill A. Shutemov wrote: > New helpers copy_from_guest()/copy_to_guest() to be used if KVM memory > protection feature is enabled. > > Signed-off-by: Kirill A. Shutemov > --- > include/linux/kvm_host.h | 4 ++ > virt/kvm/kvm_main.c | 90 +++++++++++++++++++++++++++++++--------- > 2 files changed, 75 insertions(+), 19 deletions(-) > > diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h > index 05e3c2fb3ef7..380a64613880 100644 > --- a/include/linux/kvm_host.h > +++ b/include/linux/kvm_host.h > @@ -504,6 +504,7 @@ struct kvm { > struct srcu_struct irq_srcu; > pid_t userspace_pid; > unsigned int max_halt_poll_ns; > + bool mem_protected; > }; > > #define kvm_err(fmt, ...) \ > @@ -728,6 +729,9 @@ void kvm_set_pfn_dirty(kvm_pfn_t pfn); > void kvm_set_pfn_accessed(kvm_pfn_t pfn); > void kvm_get_pfn(kvm_pfn_t pfn); > > +int copy_from_guest(void *data, unsigned long hva, int len, bool protected); > +int copy_to_guest(unsigned long hva, const void *data, int len, bool protected); > + > void kvm_release_pfn(kvm_pfn_t pfn, bool dirty, struct gfn_to_pfn_cache *cache); > int kvm_read_guest_page(struct kvm *kvm, gfn_t gfn, void *data, int offset, > int len); > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > index cf88233b819a..a9884cb8c867 100644 > --- a/virt/kvm/kvm_main.c > +++ b/virt/kvm/kvm_main.c > @@ -2313,19 +2313,70 @@ static int next_segment(unsigned long len, int offset) > return len; > } > > +int copy_from_guest(void *data, unsigned long hva, int len, bool protected) > +{ > + int offset = offset_in_page(hva); > + struct page *page; > + int npages, seg; > + > + if (!protected) > + return __copy_from_user(data, (void __user *)hva, len); > + > + might_fault(); > + kasan_check_write(data, len); > + check_object_size(data, len, false); > + > + while ((seg = next_segment(len, offset)) != 0) { > + npages = get_user_pages_unlocked(hva, 1, &page, 0); > + if (npages != 1) > + return -EFAULT; > + memcpy(data, page_address(page) + offset, seg); > + put_page(page); > + len -= seg; > + hva += seg; > + offset = 0; Why is data not updated on each iteration? > + } > + > + return 0; > +} > + > +int copy_to_guest(unsigned long hva, const void *data, int len, bool protected) > +{ > + int offset = offset_in_page(hva); > + struct page *page; > + int npages, seg; > + > + if (!protected) > + return __copy_to_user((void __user *)hva, data, len); > + > + might_fault(); > + kasan_check_read(data, len); > + check_object_size(data, len, true); > + > + while ((seg = next_segment(len, offset)) != 0) { > + npages = get_user_pages_unlocked(hva, 1, &page, FOLL_WRITE); > + if (npages != 1) > + return -EFAULT; > + memcpy(page_address(page) + offset, data, seg); > + put_page(page); > + len -= seg; > + hva += seg; > + offset = 0; Same question? Doesn't this result in *data being copied to multiple pages? Ira > + } > + > + return 0; > +} > + > static int __kvm_read_guest_page(struct kvm_memory_slot *slot, gfn_t gfn, > - void *data, int offset, int len) > + void *data, int offset, int len, > + bool protected) > { > - int r; > unsigned long addr; > > addr = gfn_to_hva_memslot_prot(slot, gfn, NULL); > if (kvm_is_error_hva(addr)) > return -EFAULT; > - r = __copy_from_user(data, (void __user *)addr + offset, len); > - if (r) > - return -EFAULT; > - return 0; > + return copy_from_guest(data, addr + offset, len, protected); > } > > int kvm_read_guest_page(struct kvm *kvm, gfn_t gfn, void *data, int offset, > @@ -2333,7 +2384,8 @@ int kvm_read_guest_page(struct kvm *kvm, gfn_t gfn, void *data, int offset, > { > struct kvm_memory_slot *slot = gfn_to_memslot(kvm, gfn); > > - return __kvm_read_guest_page(slot, gfn, data, offset, len); > + return __kvm_read_guest_page(slot, gfn, data, offset, len, > + kvm->mem_protected); > } > EXPORT_SYMBOL_GPL(kvm_read_guest_page); > > @@ -2342,7 +2394,8 @@ int kvm_vcpu_read_guest_page(struct kvm_vcpu *vcpu, gfn_t gfn, void *data, > { > struct kvm_memory_slot *slot = kvm_vcpu_gfn_to_memslot(vcpu, gfn); > > - return __kvm_read_guest_page(slot, gfn, data, offset, len); > + return __kvm_read_guest_page(slot, gfn, data, offset, len, > + vcpu->kvm->mem_protected); > } > EXPORT_SYMBOL_GPL(kvm_vcpu_read_guest_page); > > @@ -2415,7 +2468,8 @@ int kvm_vcpu_read_guest_atomic(struct kvm_vcpu *vcpu, gpa_t gpa, > EXPORT_SYMBOL_GPL(kvm_vcpu_read_guest_atomic); > > static int __kvm_write_guest_page(struct kvm_memory_slot *memslot, gfn_t gfn, > - const void *data, int offset, int len) > + const void *data, int offset, int len, > + bool protected) > { > int r; > unsigned long addr; > @@ -2423,7 +2477,8 @@ static int __kvm_write_guest_page(struct kvm_memory_slot *memslot, gfn_t gfn, > addr = gfn_to_hva_memslot(memslot, gfn); > if (kvm_is_error_hva(addr)) > return -EFAULT; > - r = __copy_to_user((void __user *)addr + offset, data, len); > + > + r = copy_to_guest(addr + offset, data, len, protected); > if (r) > return -EFAULT; > mark_page_dirty_in_slot(memslot, gfn); > @@ -2435,7 +2490,8 @@ int kvm_write_guest_page(struct kvm *kvm, gfn_t gfn, > { > struct kvm_memory_slot *slot = gfn_to_memslot(kvm, gfn); > > - return __kvm_write_guest_page(slot, gfn, data, offset, len); > + return __kvm_write_guest_page(slot, gfn, data, offset, len, > + kvm->mem_protected); > } > EXPORT_SYMBOL_GPL(kvm_write_guest_page); > > @@ -2444,7 +2500,8 @@ int kvm_vcpu_write_guest_page(struct kvm_vcpu *vcpu, gfn_t gfn, > { > struct kvm_memory_slot *slot = kvm_vcpu_gfn_to_memslot(vcpu, gfn); > > - return __kvm_write_guest_page(slot, gfn, data, offset, len); > + return __kvm_write_guest_page(slot, gfn, data, offset, len, > + vcpu->kvm->mem_protected); > } > EXPORT_SYMBOL_GPL(kvm_vcpu_write_guest_page); > > @@ -2560,7 +2617,7 @@ int kvm_write_guest_offset_cached(struct kvm *kvm, struct gfn_to_hva_cache *ghc, > if (unlikely(!ghc->memslot)) > return kvm_write_guest(kvm, gpa, data, len); > > - r = __copy_to_user((void __user *)ghc->hva + offset, data, len); > + r = copy_to_guest(ghc->hva + offset, data, len, kvm->mem_protected); > if (r) > return -EFAULT; > mark_page_dirty_in_slot(ghc->memslot, gpa >> PAGE_SHIFT); > @@ -2581,7 +2638,6 @@ int kvm_read_guest_offset_cached(struct kvm *kvm, struct gfn_to_hva_cache *ghc, > unsigned long len) > { > struct kvm_memslots *slots = kvm_memslots(kvm); > - int r; > gpa_t gpa = ghc->gpa + offset; > > BUG_ON(len + offset > ghc->len); > @@ -2597,11 +2653,7 @@ int kvm_read_guest_offset_cached(struct kvm *kvm, struct gfn_to_hva_cache *ghc, > if (unlikely(!ghc->memslot)) > return kvm_read_guest(kvm, gpa, data, len); > > - r = __copy_from_user(data, (void __user *)ghc->hva + offset, len); > - if (r) > - return -EFAULT; > - > - return 0; > + return copy_from_guest(data, ghc->hva + offset, len, kvm->mem_protected); > } > EXPORT_SYMBOL_GPL(kvm_read_guest_offset_cached); > > -- > 2.26.2 > >