From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:46414 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750981AbcCLHEx (ORCPT ); Sat, 12 Mar 2016 02:04:53 -0500 Subject: Patch "KVM: PPC: Book3S HV: Sanitize special-purpose register values on guest exit" has been added to the 4.4-stable tree To: paulus@samba.org, david@gibson.dropbear.id.au, gregkh@linuxfoundation.org, thuth@redhat.com Cc: , From: Date: Fri, 11 Mar 2016 23:04:34 -0800 Message-ID: <14577662741335@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: This is a note to let you know that I've just added the patch titled KVM: PPC: Book3S HV: Sanitize special-purpose register values on guest exit to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: kvm-ppc-book3s-hv-sanitize-special-purpose-register-values-on-guest-exit.patch and it can be found in the queue-4.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >>From ccec44563b18a0ce90e2d4f332784b3cb25c8e9c Mon Sep 17 00:00:00 2001 From: Paul Mackerras Date: Sat, 5 Mar 2016 19:34:39 +1100 Subject: KVM: PPC: Book3S HV: Sanitize special-purpose register values on guest exit 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: Greg Kroah-Hartman --- arch/powerpc/kvm/book3s_hv_rmhandlers.S | 14 ++++++++++++++ 1 file changed, 14 insertions(+) --- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S +++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S @@ -1370,6 +1370,20 @@ 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 */ Patches currently in stable-queue which might be from paulus@samba.org are queue-4.4/kvm-ppc-book3s-hv-sanitize-special-purpose-register-values-on-guest-exit.patch