From patchwork Sun Aug 21 15:29:40 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Willy Tarreau X-Patchwork-Id: 9292515 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 55D5F60574 for ; Sun, 21 Aug 2016 16:00:17 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 453F4287BE for ; Sun, 21 Aug 2016 16:00:17 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 3803828910; Sun, 21 Aug 2016 16:00:17 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id AB14E28823 for ; Sun, 21 Aug 2016 16:00:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932707AbcHUP7s (ORCPT ); Sun, 21 Aug 2016 11:59:48 -0400 Received: from wtarreau.pck.nerim.net ([62.212.114.60]:55606 "EHLO 1wt.eu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932594AbcHUPdk (ORCPT ); Sun, 21 Aug 2016 11:33:40 -0400 Received: (from willy@localhost) by pcw.home.local (8.15.2/8.15.2/Submit) id u7LFWFn4013305; Sun, 21 Aug 2016 17:32:15 +0200 From: Willy Tarreau To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: James Hogan , Paolo Bonzini , =?UTF-8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= , Ralf Baechle , linux-mips@linux-mips.org, kvm@vger.kernel.org, Willy Tarreau Subject: [PATCH 3.10 050/180] MIPS: KVM: Fix mapped fault broken commpage handling Date: Sun, 21 Aug 2016 17:29:40 +0200 Message-Id: <1471793510-13022-51-git-send-email-w@1wt.eu> X-Mailer: git-send-email 2.8.0.rc2.1.gbe9624a In-Reply-To: <1471793510-13022-1-git-send-email-w@1wt.eu> References: <1471793510-13022-1-git-send-email-w@1wt.eu> MIME-Version: 1.0 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: James Hogan commit c604cffa93478f8888bec62b23d6073dad03d43a upstream. kvm_mips_handle_mapped_seg_tlb_fault() appears to map the guest page at virtual address 0 to PFN 0 if the guest has created its own mapping there. The intention is unclear, but it may have been an attempt to protect the zero page from being mapped to anything but the comm page in code paths you wouldn't expect from genuine commpage accesses (guest kernel mode cache instructions on that address, hitting trapping instructions when executing from that address with a coincidental TLB eviction during the KVM handling, and guest user mode accesses to that address). Fix this to check for mappings exactly at KVM_GUEST_COMMPAGE_ADDR (it may not be at address 0 since commit 42aa12e74e91 ("MIPS: KVM: Move commpage so 0x0 is unmapped")), and set the corresponding EntryLo to be interpreted as 0 (invalid). Fixes: 858dd5d45733 ("KVM/MIPS32: MMU/TLB operations for the Guest.") Signed-off-by: James Hogan Cc: Paolo Bonzini Cc: "Radim Krčmář" Cc: Ralf Baechle Cc: linux-mips@linux-mips.org Cc: kvm@vger.kernel.org Signed-off-by: Radim Krčmář [james.hogan@imgtec.com: Backport to v3.10.y - v3.15.y] Signed-off-by: James Hogan Signed-off-by: Willy Tarreau --- arch/mips/kvm/kvm_tlb.c | 32 +++++++++++++++++++------------- 1 file changed, 19 insertions(+), 13 deletions(-) diff --git a/arch/mips/kvm/kvm_tlb.c b/arch/mips/kvm/kvm_tlb.c index c777dd3..1e6b1f1 100644 --- a/arch/mips/kvm/kvm_tlb.c +++ b/arch/mips/kvm/kvm_tlb.c @@ -397,21 +397,27 @@ kvm_mips_handle_mapped_seg_tlb_fault(struct kvm_vcpu *vcpu, unsigned long entryhi = 0, entrylo0 = 0, entrylo1 = 0; struct kvm *kvm = vcpu->kvm; pfn_t pfn0, pfn1; + long tlb_lo[2]; + tlb_lo[0] = tlb->tlb_lo0; + tlb_lo[1] = tlb->tlb_lo1; - if ((tlb->tlb_hi & VPN2_MASK) == 0) { - pfn0 = 0; - pfn1 = 0; - } else { - if (kvm_mips_map_page(kvm, mips3_tlbpfn_to_paddr(tlb->tlb_lo0) >> PAGE_SHIFT) < 0) - return -1; + /* + * The commpage address must not be mapped to anything else if the guest + * TLB contains entries nearby, or commpage accesses will break. + */ + if (!((tlb->tlb_hi ^ KVM_GUEST_COMMPAGE_ADDR) & + VPN2_MASK & (PAGE_MASK << 1))) + tlb_lo[(KVM_GUEST_COMMPAGE_ADDR >> PAGE_SHIFT) & 1] = 0; - if (kvm_mips_map_page(kvm, mips3_tlbpfn_to_paddr(tlb->tlb_lo1) >> PAGE_SHIFT) < 0) - return -1; + if (kvm_mips_map_page(kvm, mips3_tlbpfn_to_paddr(tlb_lo[0]) >> PAGE_SHIFT) < 0) + return -1; - pfn0 = kvm->arch.guest_pmap[mips3_tlbpfn_to_paddr(tlb->tlb_lo0) >> PAGE_SHIFT]; - pfn1 = kvm->arch.guest_pmap[mips3_tlbpfn_to_paddr(tlb->tlb_lo1) >> PAGE_SHIFT]; - } + if (kvm_mips_map_page(kvm, mips3_tlbpfn_to_paddr(tlb_lo[1]) >> PAGE_SHIFT) < 0) + return -1; + + pfn0 = kvm->arch.guest_pmap[mips3_tlbpfn_to_paddr(tlb_lo[0]) >> PAGE_SHIFT]; + pfn1 = kvm->arch.guest_pmap[mips3_tlbpfn_to_paddr(tlb_lo[1]) >> PAGE_SHIFT]; if (hpa0) *hpa0 = pfn0 << PAGE_SHIFT; @@ -423,9 +429,9 @@ kvm_mips_handle_mapped_seg_tlb_fault(struct kvm_vcpu *vcpu, entryhi = (tlb->tlb_hi & VPN2_MASK) | (KVM_GUEST_KERNEL_MODE(vcpu) ? kvm_mips_get_kernel_asid(vcpu) : kvm_mips_get_user_asid(vcpu)); entrylo0 = mips3_paddr_to_tlbpfn(pfn0 << PAGE_SHIFT) | (0x3 << 3) | - (tlb->tlb_lo0 & MIPS3_PG_D) | (tlb->tlb_lo0 & MIPS3_PG_V); + (tlb_lo[0] & MIPS3_PG_D) | (tlb_lo[0] & MIPS3_PG_V); entrylo1 = mips3_paddr_to_tlbpfn(pfn1 << PAGE_SHIFT) | (0x3 << 3) | - (tlb->tlb_lo1 & MIPS3_PG_D) | (tlb->tlb_lo1 & MIPS3_PG_V); + (tlb_lo[1] & MIPS3_PG_D) | (tlb_lo[1] & MIPS3_PG_V); #ifdef DEBUG kvm_debug("@ %#lx tlb_lo0: 0x%08lx tlb_lo1: 0x%08lx\n", vcpu->arch.pc,