From patchwork Thu Jul 14 08:16:19 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Jiri Slaby X-Patchwork-Id: 9229235 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 C9B036075D for ; Thu, 14 Jul 2016 08:20:20 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id B709126A4D for ; Thu, 14 Jul 2016 08:20:20 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id A94F628159; Thu, 14 Jul 2016 08:20:20 +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 2258926A4D for ; Thu, 14 Jul 2016 08:20:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751113AbcGNITU (ORCPT ); Thu, 14 Jul 2016 04:19:20 -0400 Received: from mx2.suse.de ([195.135.220.15]:55252 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751730AbcGNIS1 (ORCPT ); Thu, 14 Jul 2016 04:18:27 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de X-Amavis-Alert: BAD HEADER SECTION, Duplicate header field: "References" Received: from relay1.suse.de (charybdis-ext.suse.de [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id F1288AE09; Thu, 14 Jul 2016 08:16:55 +0000 (UTC) From: Jiri Slaby To: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org, James Hogan , Paolo Bonzini , =?UTF-8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= , Ralf Baechle , kvm@vger.kernel.org, linux-mips@linux-mips.org, Jiri Slaby Subject: [PATCH 3.12 87/88] MIPS: KVM: Fix modular KVM under QEMU Date: Thu, 14 Jul 2016 10:16:19 +0200 Message-Id: X-Mailer: git-send-email 2.9.1 In-Reply-To: <3d4036cb9b963cdd270c02856a888183da0623db.1468483951.git.jslaby@suse.cz> References: <3d4036cb9b963cdd270c02856a888183da0623db.1468483951.git.jslaby@suse.cz> In-Reply-To: References: 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 3.12-stable review patch. If anyone has any objections, please let me know. =============== commit 797179bc4fe06c89e47a9f36f886f68640b423f8 upstream. Copy __kvm_mips_vcpu_run() into unmapped memory, so that we can never get a TLB refill exception in it when KVM is built as a module. This was observed to happen with the host MIPS kernel running under QEMU, due to a not entirely transparent optimisation in the QEMU TLB handling where TLB entries replaced with TLBWR are copied to a separate part of the TLB array. Code in those pages continue to be executable, but those mappings persist only until the next ASID switch, even if they are marked global. An ASID switch happens in __kvm_mips_vcpu_run() at exception level after switching to the guest exception base. Subsequent TLB mapped kernel instructions just prior to switching to the guest trigger a TLB refill exception, which enters the guest exception handlers without updating EPC. This appears as a guest triggered TLB refill on a host kernel mapped (host KSeg2) address, which is not handled correctly as user (guest) mode accesses to kernel (host) segments always generate address error exceptions. Signed-off-by: James Hogan Cc: Paolo Bonzini Cc: Radim Krčmář Cc: Ralf Baechle Cc: kvm@vger.kernel.org Cc: linux-mips@linux-mips.org Signed-off-by: Paolo Bonzini [james.hogan@imgtec.com: backported for stable 3.14] Signed-off-by: James Hogan Signed-off-by: Jiri Slaby --- arch/mips/include/asm/kvm_host.h | 1 + arch/mips/kvm/kvm_locore.S | 1 + arch/mips/kvm/kvm_mips.c | 11 ++++++++++- arch/mips/kvm/kvm_mips_int.h | 2 ++ 4 files changed, 14 insertions(+), 1 deletion(-) diff --git a/arch/mips/include/asm/kvm_host.h b/arch/mips/include/asm/kvm_host.h index 4d6fa0bf1305..883a162083af 100644 --- a/arch/mips/include/asm/kvm_host.h +++ b/arch/mips/include/asm/kvm_host.h @@ -349,6 +349,7 @@ struct kvm_mips_tlb { #define KVM_MIPS_GUEST_TLB_SIZE 64 struct kvm_vcpu_arch { void *host_ebase, *guest_ebase; + int (*vcpu_run)(struct kvm_run *run, struct kvm_vcpu *vcpu); unsigned long host_stack; unsigned long host_gp; diff --git a/arch/mips/kvm/kvm_locore.S b/arch/mips/kvm/kvm_locore.S index ba5ce99c021d..d1fa2a57218b 100644 --- a/arch/mips/kvm/kvm_locore.S +++ b/arch/mips/kvm/kvm_locore.S @@ -229,6 +229,7 @@ FEXPORT(__kvm_mips_load_k0k1) /* Jump to guest */ eret +EXPORT(__kvm_mips_vcpu_run_end) VECTOR(MIPSX(exception), unknown) /* diff --git a/arch/mips/kvm/kvm_mips.c b/arch/mips/kvm/kvm_mips.c index 7e7de1f2b8ed..08972791edb4 100644 --- a/arch/mips/kvm/kvm_mips.c +++ b/arch/mips/kvm/kvm_mips.c @@ -347,6 +347,15 @@ struct kvm_vcpu *kvm_arch_vcpu_create(struct kvm *kvm, unsigned int id) memcpy(gebase + offset, mips32_GuestException, mips32_GuestExceptionEnd - mips32_GuestException); +#ifdef MODULE + offset += mips32_GuestExceptionEnd - mips32_GuestException; + memcpy(gebase + offset, (char *)__kvm_mips_vcpu_run, + __kvm_mips_vcpu_run_end - (char *)__kvm_mips_vcpu_run); + vcpu->arch.vcpu_run = gebase + offset; +#else + vcpu->arch.vcpu_run = __kvm_mips_vcpu_run; +#endif + /* Invalidate the icache for these ranges */ mips32_SyncICache((unsigned long) gebase, ALIGN(size, PAGE_SIZE)); @@ -430,7 +439,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run) kvm_guest_enter(); - r = __kvm_mips_vcpu_run(run, vcpu); + r = vcpu->arch.vcpu_run(run, vcpu); kvm_guest_exit(); local_irq_enable(); diff --git a/arch/mips/kvm/kvm_mips_int.h b/arch/mips/kvm/kvm_mips_int.h index 20da7d29eede..bf41ea36210e 100644 --- a/arch/mips/kvm/kvm_mips_int.h +++ b/arch/mips/kvm/kvm_mips_int.h @@ -27,6 +27,8 @@ #define MIPS_EXC_MAX 12 /* XXXSL More to follow */ +extern char __kvm_mips_vcpu_run_end[]; + #define C_TI (_ULCAST_(1) << 30) #define KVM_MIPS_IRQ_DELIVER_ALL_AT_ONCE (0)