From patchwork Thu Mar 10 14:09:07 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chao Peng X-Patchwork-Id: 12776410 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 89637C4321E for ; Thu, 10 Mar 2022 14:10:52 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id D39598D0005; Thu, 10 Mar 2022 09:10:51 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id CE8E58D0001; Thu, 10 Mar 2022 09:10:51 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id B8A108D0005; Thu, 10 Mar 2022 09:10:51 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (relay.hostedemail.com [64.99.140.27]) by kanga.kvack.org (Postfix) with ESMTP id AB0F98D0001 for ; Thu, 10 Mar 2022 09:10:51 -0500 (EST) Received: from smtpin12.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay13.hostedemail.com (Postfix) with ESMTP id 62E9561C75 for ; Thu, 10 Mar 2022 14:10:51 +0000 (UTC) X-FDA: 79228662702.12.15854C9 Received: from mga18.intel.com (mga18.intel.com [134.134.136.126]) by imf16.hostedemail.com (Postfix) with ESMTP id 30D92180015 for ; Thu, 10 Mar 2022 14:10:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1646921450; x=1678457450; h=from:to:cc:subject:date:message-id:in-reply-to: references; bh=uGzkzAL8Dy+iBgRDUMsNImudpdJ03OH3v6JTl1qmo+Y=; b=hPPEWNUi5+KYqs3o9rArvISZ4asnrQ+uiiLdp9Ecx3IGGMpzxST5ThRh n3/soFlCAzXO/weB/rQ1ix8is6zss4B61PIAMhSTfuHb5i7MegP+TfT6g uDB0Yw/p0pLcGcfp4YgkWtZjEAJ/0K2k/socthhQ+cnYeMGNazGV/yc9+ U7896OqmKi+30Tzu3lcNf2eHJDlrnZPtW0oaqCpQt6dfuvLice1qB1PlA GanB39dYlYLkSbv03OruesMnMy1XyofFh+uGOikiPk9rZBMw0LzUjbDyK GujvLTFKx43+RYZPT+KuA4FkedgDDcLRTPkXFGUmxMY0UqV0e8X7fP7AB w==; X-IronPort-AV: E=McAfee;i="6200,9189,10281"; a="237426405" X-IronPort-AV: E=Sophos;i="5.90,170,1643702400"; d="scan'208";a="237426405" Received: from orsmga008.jf.intel.com ([10.7.209.65]) by orsmga106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 10 Mar 2022 06:10:48 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.90,170,1643702400"; d="scan'208";a="554655113" Received: from chaop.bj.intel.com ([10.240.192.101]) by orsmga008.jf.intel.com with ESMTP; 10 Mar 2022 06:10:41 -0800 From: Chao Peng To: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org, qemu-devel@nongnu.org Cc: Paolo Bonzini , Jonathan Corbet , Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org, "H . Peter Anvin" , Hugh Dickins , Jeff Layton , "J . Bruce Fields" , Andrew Morton , Mike Rapoport , Steven Price , "Maciej S . Szmigiero" , Vlastimil Babka , Vishal Annapurve , Yu Zhang , Chao Peng , "Kirill A . Shutemov" , luto@kernel.org, jun.nakajima@intel.com, dave.hansen@intel.com, ak@linux.intel.com, david@redhat.com Subject: [PATCH v5 09/13] KVM: Handle page fault for private memory Date: Thu, 10 Mar 2022 22:09:07 +0800 Message-Id: <20220310140911.50924-10-chao.p.peng@linux.intel.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20220310140911.50924-1-chao.p.peng@linux.intel.com> References: <20220310140911.50924-1-chao.p.peng@linux.intel.com> X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 30D92180015 X-Rspam-User: Authentication-Results: imf16.hostedemail.com; dkim=pass header.d=intel.com header.s=Intel header.b=hPPEWNUi; spf=none (imf16.hostedemail.com: domain of chao.p.peng@linux.intel.com has no SPF policy when checking 134.134.136.126) smtp.mailfrom=chao.p.peng@linux.intel.com; dmarc=pass (policy=none) header.from=intel.com X-Stat-Signature: 3j95u9fiwreasdpa1pniufy6yr9fyk5x X-HE-Tag: 1646921449-727445 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: When page fault happens for a memslot with KVM_MEM_PRIVATE, we use kvm_memfile_get_pfn() which further calls into memfile_pfn_ops callbacks defined for each memslot to request the pfn from the memory backing store. One assumption is that private pages are persistent and pre-allocated in the private memory fd (backing store) so KVM uses this information as an indicator for a page is private or shared (i.e. the private fd is the final source of truth as to whether or not a GPA is private). Depending on the access is private or shared, we go different paths: - For private access, KVM checks if the page is already allocated in the memory backing store, if yes KVM establishes the mapping, otherwise exits to userspace to convert a shared page to private one. - For shared access, KVM also checks if the page is already allocated in the memory backing store, if yes then exit to userspace to convert a private page to shared one, otherwise it's treated as a traditional hva-based shared memory, KVM lets existing code to obtain a pfn with get_user_pages() and establish the mapping. Signed-off-by: Yu Zhang Signed-off-by: Chao Peng --- arch/x86/kvm/mmu/mmu.c | 73 ++++++++++++++++++++++++++++++++-- arch/x86/kvm/mmu/paging_tmpl.h | 11 +++-- 2 files changed, 77 insertions(+), 7 deletions(-) diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 3b8da8b0745e..f04c823ea09a 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -2844,6 +2844,9 @@ int kvm_mmu_max_mapping_level(struct kvm *kvm, if (max_level == PG_LEVEL_4K) return PG_LEVEL_4K; + if (kvm_slot_is_private(slot)) + return max_level; + host_level = host_pfn_mapping_level(kvm, gfn, pfn, slot); return min(host_level, max_level); } @@ -3890,7 +3893,59 @@ static bool kvm_arch_setup_async_pf(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, kvm_vcpu_gfn_to_hva(vcpu, gfn), &arch); } -static bool kvm_faultin_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault, int *r) +static bool kvm_vcpu_is_private_gfn(struct kvm_vcpu *vcpu, gfn_t gfn) +{ + /* + * At this time private gfn has not been supported yet. Other patch + * that enables it should change this. + */ + return false; +} + +static bool kvm_faultin_pfn_private(struct kvm_vcpu *vcpu, + struct kvm_page_fault *fault, + bool *is_private_pfn, int *r) +{ + int order; + unsigned int flags = 0; + struct kvm_memory_slot *slot = fault->slot; + long pfn = kvm_memfile_get_pfn(slot, fault->gfn, &order); + + if (kvm_vcpu_is_private_gfn(vcpu, fault->addr >> PAGE_SHIFT)) { + if (pfn < 0) + flags |= KVM_MEMORY_EXIT_FLAG_PRIVATE; + else { + fault->pfn = pfn; + if (slot->flags & KVM_MEM_READONLY) + fault->map_writable = false; + else + fault->map_writable = true; + + if (order == 0) + fault->max_level = PG_LEVEL_4K; + *is_private_pfn = true; + *r = RET_PF_FIXED; + return true; + } + } else { + if (pfn < 0) + return false; + + kvm_memfile_put_pfn(slot, pfn); + } + + vcpu->run->exit_reason = KVM_EXIT_MEMORY_ERROR; + vcpu->run->memory.flags = flags; + vcpu->run->memory.padding = 0; + vcpu->run->memory.gpa = fault->gfn << PAGE_SHIFT; + vcpu->run->memory.size = PAGE_SIZE; + fault->pfn = -1; + *r = -1; + return true; +} + +static bool kvm_faultin_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault, + bool *is_private_pfn, int *r) { struct kvm_memory_slot *slot = fault->slot; bool async; @@ -3924,6 +3979,10 @@ static bool kvm_faultin_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault, } } + if (kvm_slot_is_private(slot) && + kvm_faultin_pfn_private(vcpu, fault, is_private_pfn, r)) + return *r == RET_PF_FIXED ? false : true; + async = false; fault->pfn = __gfn_to_pfn_memslot(slot, fault->gfn, false, &async, fault->write, &fault->map_writable, @@ -3984,6 +4043,7 @@ static int direct_page_fault(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault bool is_tdp_mmu_fault = is_tdp_mmu(vcpu->arch.mmu); unsigned long mmu_seq; + bool is_private_pfn = false; int r; fault->gfn = fault->addr >> PAGE_SHIFT; @@ -4003,7 +4063,7 @@ static int direct_page_fault(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault mmu_seq = vcpu->kvm->mmu_notifier_seq; smp_rmb(); - if (kvm_faultin_pfn(vcpu, fault, &r)) + if (kvm_faultin_pfn(vcpu, fault, &is_private_pfn, &r)) return r; if (handle_abnormal_pfn(vcpu, fault, ACC_ALL, &r)) @@ -4016,7 +4076,7 @@ static int direct_page_fault(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault else write_lock(&vcpu->kvm->mmu_lock); - if (is_page_fault_stale(vcpu, fault, mmu_seq)) + if (!is_private_pfn && is_page_fault_stale(vcpu, fault, mmu_seq)) goto out_unlock; r = make_mmu_pages_available(vcpu); @@ -4033,7 +4093,12 @@ static int direct_page_fault(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault read_unlock(&vcpu->kvm->mmu_lock); else write_unlock(&vcpu->kvm->mmu_lock); - kvm_release_pfn_clean(fault->pfn); + + if (is_private_pfn) + kvm_memfile_put_pfn(fault->slot, fault->pfn); + else + kvm_release_pfn_clean(fault->pfn); + return r; } diff --git a/arch/x86/kvm/mmu/paging_tmpl.h b/arch/x86/kvm/mmu/paging_tmpl.h index 252c77805eb9..6a5736699c0a 100644 --- a/arch/x86/kvm/mmu/paging_tmpl.h +++ b/arch/x86/kvm/mmu/paging_tmpl.h @@ -825,6 +825,8 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault int r; unsigned long mmu_seq; bool is_self_change_mapping; + bool is_private_pfn = false; + pgprintk("%s: addr %lx err %x\n", __func__, fault->addr, fault->error_code); WARN_ON_ONCE(fault->is_tdp); @@ -873,7 +875,7 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault mmu_seq = vcpu->kvm->mmu_notifier_seq; smp_rmb(); - if (kvm_faultin_pfn(vcpu, fault, &r)) + if (kvm_faultin_pfn(vcpu, fault, &is_private_pfn, &r)) return r; if (handle_abnormal_pfn(vcpu, fault, walker.pte_access, &r)) @@ -901,7 +903,7 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault r = RET_PF_RETRY; write_lock(&vcpu->kvm->mmu_lock); - if (is_page_fault_stale(vcpu, fault, mmu_seq)) + if (!is_private_pfn && is_page_fault_stale(vcpu, fault, mmu_seq)) goto out_unlock; r = make_mmu_pages_available(vcpu); @@ -911,7 +913,10 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault out_unlock: write_unlock(&vcpu->kvm->mmu_lock); - kvm_release_pfn_clean(fault->pfn); + if (is_private_pfn) + kvm_memfile_put_pfn(fault->slot, fault->pfn); + else + kvm_release_pfn_clean(fault->pfn); return r; }