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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_2 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 22C8AC3A59D for ; Thu, 22 Aug 2019 10:29:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 038E723404 for ; Thu, 22 Aug 2019 10:29:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732245AbfHVK3z (ORCPT ); Thu, 22 Aug 2019 06:29:55 -0400 Received: from szxga04-in.huawei.com ([45.249.212.190]:5192 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1730309AbfHVK3z (ORCPT ); Thu, 22 Aug 2019 06:29:55 -0400 Received: from DGGEMS405-HUB.china.huawei.com (unknown [172.30.72.60]) by Forcepoint Email with ESMTP id B334BCD1D3E5D29EB50F; Thu, 22 Aug 2019 18:29:50 +0800 (CST) Received: from localhost (10.202.226.61) by DGGEMS405-HUB.china.huawei.com (10.3.19.205) with Microsoft SMTP Server id 14.3.439.0; Thu, 22 Aug 2019 18:29:44 +0800 Date: Thu, 22 Aug 2019 11:29:30 +0100 From: Jonathan Cameron To: Steven Price CC: Marc Zyngier , Will Deacon , , , "Mark Rutland" , , , Radim =?UTF-8?Q?Kr=C4=8Dm=C3=A1=C5=99?= , Catalin Marinas , "Suzuki K Pouloze" , , "Russell King" , James Morse , "Paolo Bonzini" , Julien Thierry Subject: Re: [PATCH v3 04/10] KVM: Implement kvm_put_guest() Message-ID: <20190822112930.000052db@huawei.com> In-Reply-To: <20190821153656.33429-5-steven.price@arm.com> References: <20190821153656.33429-1-steven.price@arm.com> <20190821153656.33429-5-steven.price@arm.com> Organization: Huawei X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; i686-w64-mingw32) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.202.226.61] X-CFilter-Loop: Reflected Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Wed, 21 Aug 2019 16:36:50 +0100 Steven Price wrote: > kvm_put_guest() is analogous to put_user() - it writes a single value to > the guest physical address. The implementation is built upon put_user() > and so it has the same single copy atomic properties. > > Signed-off-by: Steven Price > --- > include/linux/kvm_host.h | 24 ++++++++++++++++++++++++ > 1 file changed, 24 insertions(+) > > diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h > index fcb46b3374c6..e154a1897e20 100644 > --- a/include/linux/kvm_host.h > +++ b/include/linux/kvm_host.h > @@ -746,6 +746,30 @@ int kvm_write_guest_offset_cached(struct kvm *kvm, struct gfn_to_hva_cache *ghc, > unsigned long len); > int kvm_gfn_to_hva_cache_init(struct kvm *kvm, struct gfn_to_hva_cache *ghc, > gpa_t gpa, unsigned long len); > + > +#define __kvm_put_guest(kvm, gfn, offset, value, type) \ > +({ \ > + unsigned long __addr = gfn_to_hva(kvm, gfn); \ > + type __user *__uaddr = (type __user *)(__addr + offset); \ > + int __ret = 0; \ Why initialize __ret? > + \ > + if (kvm_is_error_hva(__addr)) \ > + __ret = -EFAULT; \ > + else \ > + __ret = put_user(value, __uaddr); \ > + if (!__ret) \ > + mark_page_dirty(kvm, gfn); \ > + __ret; \ > +}) > + > +#define kvm_put_guest(kvm, gpa, value, type) \ > +({ \ > + gpa_t __gpa = gpa; \ > + struct kvm *__kvm = kvm; \ > + __kvm_put_guest(__kvm, __gpa >> PAGE_SHIFT, \ > + offset_in_page(__gpa), (value), type); \ > +}) > + > int kvm_clear_guest_page(struct kvm *kvm, gfn_t gfn, int offset, int len); > int kvm_clear_guest(struct kvm *kvm, gpa_t gpa, unsigned long len); > struct kvm_memory_slot *gfn_to_memslot(struct kvm *kvm, gfn_t gfn);