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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 205B5C0018C for ; Mon, 6 Nov 2023 13:30:58 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 3D0996B024E; Mon, 6 Nov 2023 08:30:58 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 357FD6B024F; Mon, 6 Nov 2023 08:30:58 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 1D1FF6B0250; Mon, 6 Nov 2023 08:30:58 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id 0F8656B024E for ; Mon, 6 Nov 2023 08:30:58 -0500 (EST) Received: from smtpin16.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id C8F84120473 for ; Mon, 6 Nov 2023 13:30:57 +0000 (UTC) X-FDA: 81427614954.16.27998C1 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.10]) by imf08.hostedemail.com (Postfix) with ESMTP id EBC1B16001D for ; Mon, 6 Nov 2023 13:30:54 +0000 (UTC) Authentication-Results: imf08.hostedemail.com; dkim=pass header.d=intel.com header.s=Intel header.b=kdhBy6xC; dmarc=pass (policy=none) header.from=intel.com; spf=none (imf08.hostedemail.com: domain of yilun.xu@linux.intel.com has no SPF policy when checking 198.175.65.10) smtp.mailfrom=yilun.xu@linux.intel.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1699277455; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=sKN9wen/tm7cB97ghnIhNBCP5XfRBMi4Tg5ZYI9TW8s=; b=6LK9YKSD+BCJH3mIKWgARWZ+s2tXMLaOi8LSqtCl1/QNhzpj4CCu5B1IgWHcvjHdfsmOTz +7ZqxgVvq2zUb6gDZJ2Ntmt52COepVhdZu8CqAqZu2vnkVIyYfV3d7MdjUKPMqklUvpgwA uwP0TzC0yFqQ1HUNghBdePbIIiWA9Bk= ARC-Authentication-Results: i=1; imf08.hostedemail.com; dkim=pass header.d=intel.com header.s=Intel header.b=kdhBy6xC; dmarc=pass (policy=none) header.from=intel.com; spf=none (imf08.hostedemail.com: domain of yilun.xu@linux.intel.com has no SPF policy when checking 198.175.65.10) smtp.mailfrom=yilun.xu@linux.intel.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1699277455; a=rsa-sha256; cv=none; b=f8HXFSfOXOCQQle6/pTtAnz7tCF/K7cPA/oaAtsVqxdfNTg2WXFVHBg5O4/C7OWyvFqm3d NPpVvV3AOXw1RfUabeyoKGHUOZJW+R230r9t0SA12MmMWtowEBoEMhSKWRNISfDK2oo7VU 5QlgYKkh/4GFfcgoiD6ebMc4eJ7kTGw= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1699277455; x=1730813455; h=date:from:to:cc:subject:message-id:references: mime-version:content-transfer-encoding:in-reply-to; bh=GcPOwqKIRcSDpD/XkGdZ5KVAeJljJ23LDoDjt600Qfg=; b=kdhBy6xCe7hkqHpnde4xrERK2CGKSnVfVHSYBgycoUBZW2KHL8f56B8y RQ7ZsBbA1gvXcnJMeySXsCMqqFRLdU4ywv5mAk4GqzHfvtJwuG23M5kSC PEft8zwyeNQmt1Y+yY5DIkys8ACp0FVR2Uw2LOyiapX73rkp0b3bIJ0Y+ wkZTpvB73ELzRX5s1z0+unJCAC2ueiCHpPzNREHo3dgXc1cU89n/2g7Mz jJCSSa//28T2++vbh/MfldkYH/craIMgpFQz+zgvN0FzErgHKaZ3W8MbE 8VCRWmann9t6bkwml1078+bVbMDBEqT8zU5UHGQ0NZkkv5FBXS0ZpteeS w==; X-IronPort-AV: E=McAfee;i="6600,9927,10885"; a="2263464" X-IronPort-AV: E=Sophos;i="6.03,281,1694761200"; d="scan'208";a="2263464" Received: from orsmga007.jf.intel.com ([10.7.209.58]) by orvoesa102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 06 Nov 2023 05:30:53 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10885"; a="755855766" X-IronPort-AV: E=Sophos;i="6.03,281,1694761200"; d="scan'208";a="755855766" Received: from yilunxu-optiplex-7050.sh.intel.com (HELO localhost) ([10.239.159.165]) by orsmga007.jf.intel.com with ESMTP; 06 Nov 2023 05:30:42 -0800 Date: Mon, 6 Nov 2023 21:29:10 +0800 From: Xu Yilun To: Paolo Bonzini Cc: Sean Christopherson , Marc Zyngier , Oliver Upton , Huacai Chen , Michael Ellerman , Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexander Viro , Christian Brauner , "Matthew Wilcox (Oracle)" , Andrew Morton , kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Xiaoyao Li , Xu Yilun , Chao Peng , Fuad Tabba , Jarkko Sakkinen , Anish Moorthy , David Matlack , Yu Zhang , Isaku Yamahata , =?utf-8?Q?Micka=C3=ABl_Sala=C3=BCn?= , Vlastimil Babka , Vishal Annapurve , Ackerley Tng , Maciej Szmigiero , David Hildenbrand , Quentin Perret , Michael Roth , Wang , Liam Merwick , Isaku Yamahata , "Kirill A . Shutemov" Subject: Re: [PATCH v13 20/35] KVM: x86/mmu: Handle page fault for private memory Message-ID: References: <20231027182217.3615211-1-seanjc@google.com> <20231027182217.3615211-21-seanjc@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Rspam-User: X-Stat-Signature: 3ds39dk9wkox16nmct57s5z9q1i4ufp4 X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: EBC1B16001D X-HE-Tag: 1699277454-270489 X-HE-Meta: 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 SuGRvnk3 hKM7Yc97Qitmn0veYK9iul2rcbP2H0+IcECdlUM3duvAox3o/a4D8MDELDhC27wnWC3G7ymKTduUn+ev7Pl4UYSh3VFV1Ik0I3kvrJ/6mPxc1srAnLJgtj3Id4rnQNwCHdgHYRM+2qTq63j0OuM0h6YPa9QIOINE8B5DeE/fNfL8ih88wxMng6LRc08hX+wdKM8giiVp0E1K1wYcIofVYtsSm4P2Li9jL1FfRRRSfiIzMUp4BVS9CKoflAS7hhQcefyqMB+sFbbnWOZw= 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: List-Subscribe: List-Unsubscribe: On Sun, Nov 05, 2023 at 05:19:36PM +0100, Paolo Bonzini wrote: > On Sun, Nov 5, 2023 at 2:04 PM Xu Yilun wrote: > > > > > +static void kvm_mmu_prepare_memory_fault_exit(struct kvm_vcpu *vcpu, > > > + struct kvm_page_fault *fault) > > > +{ > > > + kvm_prepare_memory_fault_exit(vcpu, fault->gfn << PAGE_SHIFT, > > > + PAGE_SIZE, fault->write, fault->exec, > > > + fault->is_private); > > > +} > > > + > > > +static int kvm_faultin_pfn_private(struct kvm_vcpu *vcpu, > > > + struct kvm_page_fault *fault) > > > +{ > > > + int max_order, r; > > > + > > > + if (!kvm_slot_can_be_private(fault->slot)) { > > > + kvm_mmu_prepare_memory_fault_exit(vcpu, fault); > > > + return -EFAULT; > > > + } > > > + > > > + r = kvm_gmem_get_pfn(vcpu->kvm, fault->slot, fault->gfn, &fault->pfn, > > > + &max_order); > > > + if (r) { > > > + kvm_mmu_prepare_memory_fault_exit(vcpu, fault); > > > + return r; > > > > Why report KVM_EXIT_MEMORY_FAULT here? even with a ret != -EFAULT? > > The cases are EFAULT, EHWPOISON (which can report > KVM_EXIT_MEMORY_FAULT) and ENOMEM. I think it's fine > that even -ENOMEM can return KVM_EXIT_MEMORY_FAULT, > and it doesn't violate the documentation. The docs tell you "what > can you do if error if EFAULT or EHWPOISON?"; they don't > exclude that other errnos result in KVM_EXIT_MEMORY_FAULT, > it's just that you're not supposed to look at it Thanks, it's OK for ENOMEM + KVM_EXIT_MEMORY_FAULT. Another concern is, now 3 places to report EFAULT + KVM_EXIT_MEMORY_FAULT: if (!kvm_slot_can_be_private(fault->slot)) { kvm_mmu_prepare_memory_fault_exit(vcpu, fault); return -EFAULT; } file = kvm_gmem_get_file(slot); if (!file) return -EFAULT; if (fault->is_private != kvm_mem_is_private(vcpu->kvm, fault->gfn)) { kvm_mmu_prepare_memory_fault_exit(vcpu, fault); return -EFAULT; } They are different cases, and seems userspace should handle them differently, but not enough information to distinguish them. Thanks, Yilun > > Paolo > >