From patchwork Thu Dec 23 12:30:09 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chao Peng X-Patchwork-Id: 1572676 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: bilbo.ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=intel.com header.i=@intel.com header.a=rsa-sha256 header.s=Intel header.b=DJMjQri0; dkim-atps=neutral Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org (client-ip=209.51.188.17; helo=lists.gnu.org; envelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org; receiver=) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by bilbo.ozlabs.org (Postfix) with ESMTPS id 4JKVX96dnWz9tkD for ; Thu, 23 Dec 2021 23:54:48 +1100 (AEDT) Received: from localhost ([::1]:35410 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1n0NcL-0001jD-2v for incoming@patchwork.ozlabs.org; Thu, 23 Dec 2021 07:54:45 -0500 Received: from eggs.gnu.org ([209.51.188.92]:47440) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1n0NH8-0007Dr-HB for qemu-devel@nongnu.org; Thu, 23 Dec 2021 07:32:52 -0500 Received: from mga09.intel.com ([134.134.136.24]:61073) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1n0NH6-0002lL-MT for qemu-devel@nongnu.org; Thu, 23 Dec 2021 07:32:50 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1640262768; x=1671798768; h=from:to:cc:subject:date:message-id:in-reply-to: references; bh=pB0U4IoAn2FVqOKKSo9Pzwd6Ru3anEta8cgDh0MsBiY=; b=DJMjQri0C/KLVbTgf8Bp68e2tjO9NT5yTO0iDg27BbHzJ6PM8J09lbau eFJncyypLlboOPgTTSe2zLveyBsCcFHRmtj+EWeH4ZTJspYwjYja2auRD yAGKU5sI9yBdhTTj1V4QPHvgSDQz4Z/kKVURVKRDExtnu3zJ5NYQVrTT8 m7KpGDAhZr/uHLz3/Ix6MviaGtRK3UuqqFPbYwOhKv1Loi+4z0xNbubu2 C9WHQ6TCYN8CxBs5kt7Hzs2LLWAv1xPbrFenl7zcEZvP7PGdtdkQTJaqq sYu2lfm/rm3Omt7BHBX3F+v336ekciS9OP4Fc85ggVRUZqlgvKwpqzI0t g==; X-IronPort-AV: E=McAfee;i="6200,9189,10206"; a="240619868" X-IronPort-AV: E=Sophos;i="5.88,229,1635231600"; d="scan'208";a="240619868" Received: from orsmga008.jf.intel.com ([10.7.209.65]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 23 Dec 2021 04:32:47 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.88,229,1635231600"; d="scan'208";a="522079079" Received: from chaop.bj.intel.com ([10.240.192.101]) by orsmga008.jf.intel.com with ESMTP; 23 Dec 2021 04:32:39 -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 Subject: [PATCH v3 kvm/queue 14/16] KVM: Handle page fault for private memory Date: Thu, 23 Dec 2021 20:30:09 +0800 Message-Id: <20211223123011.41044-15-chao.p.peng@linux.intel.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20211223123011.41044-1-chao.p.peng@linux.intel.com> References: <20211223123011.41044-1-chao.p.peng@linux.intel.com> Received-SPF: none client-ip=134.134.136.24; envelope-from=chao.p.peng@linux.intel.com; helo=mga09.intel.com X-Spam_score_int: -44 X-Spam_score: -4.5 X-Spam_bar: ---- X-Spam_report: (-4.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.203, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_MED=-2.3, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_NONE=0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Wanpeng Li , jun.nakajima@intel.com, david@redhat.com, "J . Bruce Fields" , dave.hansen@intel.com, "H . Peter Anvin" , Chao Peng , ak@linux.intel.com, Jonathan Corbet , Joerg Roedel , x86@kernel.org, Hugh Dickins , Ingo Molnar , Borislav Petkov , luto@kernel.org, Thomas Gleixner , Vitaly Kuznetsov , Jim Mattson , Sean Christopherson , susie.li@intel.com, Jeff Layton , john.ji@intel.com, Yu Zhang , Paolo Bonzini , Andrew Morton , "Kirill A . Shutemov" Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" 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 | 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 2856eb662a21..fbcdf62f8281 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -2920,6 +2920,9 @@ 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); } @@ -3950,7 +3953,59 @@ 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; + 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; @@ -3984,6 +4039,10 @@ 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, @@ -4044,6 +4103,7 @@ 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; @@ -4063,7 +4123,7 @@ 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)) @@ -4076,7 +4136,7 @@ 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); @@ -4093,7 +4153,12 @@ 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 5b5bdac97c7b..640fd1e2fe4c 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; kvm_mmu_audit(vcpu, AUDIT_PRE_PAGE_FAULT); @@ -913,7 +915,10 @@ 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; }