From mboxrd@z Thu Jan 1 00:00:00 1970 Received: with ECARTIS (v1.0.0; list linux-mips); Mon, 25 Jul 2016 22:55:50 +0200 (CEST) Received: from mail.linuxfoundation.org ([140.211.169.12]:34717 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by eddie.linux-mips.org with ESMTP id S23990514AbcGYUznFgYko (ORCPT ); Mon, 25 Jul 2016 22:55:43 +0200 Received: from localhost (unknown [104.132.1.103]) by mail.linuxfoundation.org (Postfix) with ESMTPSA id A79D3726; Mon, 25 Jul 2016 20:55:36 +0000 (UTC) From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@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 Subject: [PATCH 3.14 26/53] MIPS: KVM: Fix modular KVM under QEMU Date: Mon, 25 Jul 2016 13:55:08 -0700 Message-Id: <20160725203515.400899411@linuxfoundation.org> X-Mailer: git-send-email 2.9.0 In-Reply-To: <20160725203514.202312855@linuxfoundation.org> References: <20160725203514.202312855@linuxfoundation.org> User-Agent: quilt/0.64 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Return-Path: X-Envelope-To: <"|/home/ecartis/ecartis -s linux-mips"> (uid 0) X-Orcpt: rfc822;linux-mips@linux-mips.org Original-Recipient: rfc822;linux-mips@linux-mips.org X-archive-position: 54371 X-ecartis-version: Ecartis v1.0.0 Sender: linux-mips-bounce@linux-mips.org Errors-to: linux-mips-bounce@linux-mips.org X-original-sender: gregkh@linuxfoundation.org Precedence: bulk List-help: List-unsubscribe: List-software: Ecartis version 1.0.0 List-Id: linux-mips X-List-ID: linux-mips List-subscribe: List-owner: List-post: List-archive: X-list: linux-mips 3.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: James Hogan 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 Cc: # 3.10.x- Signed-off-by: Paolo Bonzini [james.hogan@imgtec.com: backported for stable 3.14] Signed-off-by: James Hogan Signed-off-by: Greg Kroah-Hartman --- 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(-) --- a/arch/mips/include/asm/kvm_host.h +++ b/arch/mips/include/asm/kvm_host.h @@ -342,6 +342,7 @@ 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; --- 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) /* --- a/arch/mips/kvm/kvm_mips.c +++ b/arch/mips/kvm/kvm_mips.c @@ -348,6 +348,15 @@ struct kvm_vcpu *kvm_arch_vcpu_create(st 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)); @@ -431,7 +440,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_v kvm_guest_enter(); - r = __kvm_mips_vcpu_run(run, vcpu); + r = vcpu->arch.vcpu_run(run, vcpu); kvm_guest_exit(); local_irq_enable(); --- 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)