From patchwork Wed Mar 16 20:05:48 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kamal Mostafa X-Patchwork-Id: 598750 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from huckleberry.canonical.com (huckleberry.canonical.com [91.189.94.19]) by ozlabs.org (Postfix) with ESMTP id 3qQN1G0W5Lz9sdQ; Thu, 17 Mar 2016 07:11:46 +1100 (AEDT) Received: from localhost ([127.0.0.1] helo=huckleberry.canonical.com) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1agHnC-0001EB-L4; Wed, 16 Mar 2016 20:11:42 +0000 Received: from youngberry.canonical.com ([91.189.89.112]) by huckleberry.canonical.com with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.76) (envelope-from ) id 1agHjA-0007jl-O5 for kernel-team@lists.ubuntu.com; Wed, 16 Mar 2016 20:07:32 +0000 Received: from 1.general.kamal.us.vpn ([10.172.68.52] helo=fourier) by youngberry.canonical.com with esmtpsa (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.76) (envelope-from ) id 1agHjA-00084f-8b; Wed, 16 Mar 2016 20:07:32 +0000 Received: from kamal by fourier with local (Exim 4.86) (envelope-from ) id 1agHj7-0002bX-Jf; Wed, 16 Mar 2016 13:07:29 -0700 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Subject: [PATCH 3.19.y-ckt 55/70] KVM: PPC: Book3S HV: Sanitize special-purpose register values on guest exit Date: Wed, 16 Mar 2016 13:05:48 -0700 Message-Id: <1458158763-9614-56-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 2.7.0 In-Reply-To: <1458158763-9614-1-git-send-email-kamal@canonical.com> References: <1458158763-9614-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 3.19 Cc: Kamal Mostafa , Paul Mackerras X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.14 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: kernel-team-bounces@lists.ubuntu.com Sender: kernel-team-bounces@lists.ubuntu.com v3.19.8-ckt17 -stable review patch. If anyone has any objections, please let me know. ---8<------------------------------------------------------------ From: Paul Mackerras commit ccec44563b18a0ce90e2d4f332784b3cb25c8e9c upstream. Thomas Huth discovered that a guest could cause a hard hang of a host CPU by setting the Instruction Authority Mask Register (IAMR) to a suitable value. It turns out that this is because when the code was added to context-switch the new special-purpose registers (SPRs) that were added in POWER8, we forgot to add code to ensure that they were restored to a sane value on guest exit. This adds code to set those registers where a bad value could compromise the execution of the host kernel to a suitable neutral value on guest exit. Fixes: b005255e12a3 Reported-by: Thomas Huth Reviewed-by: David Gibson Signed-off-by: Paul Mackerras Signed-off-by: Kamal Mostafa --- arch/powerpc/kvm/book3s_hv_rmhandlers.S | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S index aa3016c..e731ae2 100644 --- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S +++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S @@ -1168,6 +1168,20 @@ END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_207S) std r6, VCPU_ACOP(r9) stw r7, VCPU_GUEST_PID(r9) std r8, VCPU_WORT(r9) + /* + * Restore various registers to 0, where non-zero values + * set by the guest could disrupt the host. + */ + li r0, 0 + mtspr SPRN_IAMR, r0 + mtspr SPRN_CIABR, r0 + mtspr SPRN_DAWRX, r0 + mtspr SPRN_TCSCR, r0 + mtspr SPRN_WORT, r0 + /* Set MMCRS to 1<<31 to freeze and disable the SPMC counters */ + li r0, 1 + sldi r0, r0, 31 + mtspr SPRN_MMCRS, r0 8: /* Save and reset AMR and UAMOR before turning on the MMU */