From patchwork Tue Dec 21 15:11:23 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chao Peng X-Patchwork-Id: 12689927 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 98A43C433FE for ; Tue, 21 Dec 2021 15:14:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239339AbhLUPOW (ORCPT ); Tue, 21 Dec 2021 10:14:22 -0500 Received: from mga02.intel.com ([134.134.136.20]:9908 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239194AbhLUPOM (ORCPT ); Tue, 21 Dec 2021 10:14:12 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1640099652; x=1671635652; h=from:to:cc:subject:date:message-id:in-reply-to: references; bh=IxToifQm+9Y4O1zxSJ9m5WL26XRsf9dP/O1hd+4ZWcI=; b=j6r9elk+ufSCyS5ysnvuJEsASsey4YFiQ/PzuqEIqxmp/oJi3Td0i/ns HCeJFROX9KPq6JHENUozouJ/cBEToQtmSgNAU3F8AYXRMnWLOqff+V55e ngRHtYZ7FXmcve16OTxnxAh/N6agj5iEf63LX9XhWCBmDPhg86nY80vEk DKu6/IYKzaK2/WWKb58XtqMS12Qt+4vl/3EUMtQVdZMvpwQOykgulr1I/ i9Wbue7rLZ24rNsKWnGlWXMUIbbJwBO6jxsKkxje0I8h9sMhkblXQT5Gm XLJpk0SsDUj0AIngl1xyWIgXOv/1MfV/6EPnkBlWrGthoYCh4KTYbLKFi A==; X-IronPort-AV: E=McAfee;i="6200,9189,10204"; a="227704138" X-IronPort-AV: E=Sophos;i="5.88,223,1635231600"; d="scan'208";a="227704138" Received: from orsmga005.jf.intel.com ([10.7.209.41]) by orsmga101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 21 Dec 2021 07:13:56 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.88,223,1635231600"; d="scan'208";a="684688647" Received: from chaop.bj.intel.com ([10.240.192.101]) by orsmga005.jf.intel.com with ESMTP; 21 Dec 2021 07:13:40 -0800 From: Chao Peng To: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@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 , Yu Zhang , Chao Peng , "Kirill A . Shutemov" , luto@kernel.org, john.ji@intel.com, susie.li@intel.com, jun.nakajima@intel.com, dave.hansen@intel.com, ak@linux.intel.com, david@redhat.com Subject: [PATCH v3 13/15] KVM: Handle page fault for private memory Date: Tue, 21 Dec 2021 23:11:23 +0800 Message-Id: <20211221151125.19446-14-chao.p.peng@linux.intel.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20211221151125.19446-1-chao.p.peng@linux.intel.com> References: <20211221151125.19446-1-chao.p.peng@linux.intel.com> Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org When a page fault from the secondary page table while the guest is running happens in a memslot with KVM_MEM_PRIVATE, we need go different paths for private access and shared access. - For private access, KVM checks if the page is already allocated in the memory backend, 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 backend, 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. The above code assume private memory is persistent and pre-allocated in the memory backend so KVM can use this information as an indicator for a page is private or shared. The above check is then performed by calling kvm_memfd_get_pfn() which currently is implemented as a pagecache search but in theory that can be implemented differently (i.e. when the page is even not mapped into host pagecache there should be some different implementation). Signed-off-by: Yu Zhang Signed-off-by: Chao Peng --- arch/x86/kvm/mmu/mmu.c | 64 +++++++++++++++++++++++++++++++--- arch/x86/kvm/mmu/paging_tmpl.h | 11 ++++-- 2 files changed, 68 insertions(+), 7 deletions(-) diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index a7006e1ac2d2..7fc29f85313d 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -3156,6 +3156,9 @@ 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); } @@ -4359,7 +4362,50 @@ 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_faultin_pfn_private(struct kvm_vcpu *vcpu, + struct kvm_page_fault *fault, + bool *is_private_pfn, int *r) +{ + int order; + int mem_convert_type; + struct kvm_memory_slot *slot = fault->slot; + long pfn = kvm_memfd_get_pfn(slot, fault->gfn, &order); + + if (kvm_vcpu_is_private_gfn(vcpu, fault->addr >> PAGE_SHIFT)) { + if (pfn < 0) + mem_convert_type = KVM_EXIT_MEM_MAP_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_memfd_put_pfn(pfn); + mem_convert_type = KVM_EXIT_MEM_MAP_SHARED; + } + + vcpu->run->exit_reason = KVM_EXIT_MEMORY_ERROR; + vcpu->run->mem.type = mem_convert_type; + vcpu->run->mem.u.map.gpa = fault->gfn << PAGE_SHIFT; + vcpu->run->mem.u.map.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; @@ -4400,6 +4446,10 @@ 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, @@ -4446,6 +4496,7 @@ 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 = kvm_gfn_unalias(vcpu->kvm, fault->addr); @@ -4465,7 +4516,7 @@ 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)) @@ -4504,7 +4555,7 @@ 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); @@ -4522,7 +4573,12 @@ 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_memfd_put_pfn(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 6d343a399913..ebd5c923f844 100644 --- a/arch/x86/kvm/mmu/paging_tmpl.h +++ b/arch/x86/kvm/mmu/paging_tmpl.h @@ -842,6 +842,8 @@ 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); @@ -890,7 +892,7 @@ 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)) @@ -918,7 +920,7 @@ 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; kvm_mmu_audit(vcpu, AUDIT_PRE_PAGE_FAULT); @@ -930,7 +932,10 @@ 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_memfd_put_pfn(fault->pfn); + else + kvm_release_pfn_clean(fault->pfn); return r; }