From patchwork Thu Aug 18 09:05:29 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: James Hogan X-Patchwork-Id: 9287075 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 C09646086A for ; Thu, 18 Aug 2016 09:05:58 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id B06E928FEB for ; Thu, 18 Aug 2016 09:05:58 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id A53DA28FEE; Thu, 18 Aug 2016 09:05:58 +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=ham 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 0F74F28FEC for ; Thu, 18 Aug 2016 09:05:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753483AbcHRJF4 (ORCPT ); Thu, 18 Aug 2016 05:05:56 -0400 Received: from mailapp01.imgtec.com ([195.59.15.196]:39428 "EHLO mailapp01.imgtec.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753088AbcHRJFy (ORCPT ); Thu, 18 Aug 2016 05:05:54 -0400 Received: from HHMAIL01.hh.imgtec.org (unknown [10.100.10.19]) by Forcepoint Email with ESMTPS id 52D51BC8BAEC0; Thu, 18 Aug 2016 10:05:40 +0100 (IST) Received: from jhogan-linux.le.imgtec.org (192.168.154.110) by HHMAIL01.hh.imgtec.org (10.100.10.21) with Microsoft SMTP Server (TLS) id 14.3.294.0; Thu, 18 Aug 2016 10:05:41 +0100 From: James Hogan To: CC: James Hogan , Paolo Bonzini , =?UTF-8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= , Ralf Baechle , , Subject: [PATCH BACKPORT 3.17-4.4 1/4] MIPS: KVM: Fix mapped fault broken commpage handling Date: Thu, 18 Aug 2016 10:05:29 +0100 Message-ID: <68df6d553f95e9f40311c92f7e010d90a329843a.1471018436.git-series.james.hogan@imgtec.com> X-Mailer: git-send-email 2.9.2 MIME-Version: 1.0 In-Reply-To: References: X-Originating-IP: [192.168.154.110] Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP 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 v3.17.y - v4.4.y] Signed-off-by: James Hogan --- arch/mips/kvm/tlb.c | 45 ++++++++++++++++++++++++++------------------- 1 file changed, 26 insertions(+), 19 deletions(-) diff --git a/arch/mips/kvm/tlb.c b/arch/mips/kvm/tlb.c index aed0ac2a4972..d3c5715426c4 100644 --- a/arch/mips/kvm/tlb.c +++ b/arch/mips/kvm/tlb.c @@ -361,24 +361,31 @@ int 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]; - 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; - - if (kvm_mips_map_page(kvm, mips3_tlbpfn_to_paddr(tlb->tlb_lo1) - >> 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]; - } + tlb_lo[0] = tlb->tlb_lo0; + tlb_lo[1] = tlb->tlb_lo1; + + /* + * 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_lo[0]) + >> PAGE_SHIFT) < 0) + return -1; + + 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; @@ -391,9 +398,9 @@ int kvm_mips_handle_mapped_seg_tlb_fault(struct kvm_vcpu *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); kvm_debug("@ %#lx tlb_lo0: 0x%08lx tlb_lo1: 0x%08lx\n", vcpu->arch.pc, tlb->tlb_lo0, tlb->tlb_lo1);