From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.kernel.org ([198.145.29.99]:47520 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389318AbeKLIVG (ORCPT ); Mon, 12 Nov 2018 03:21:06 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Christopher Dall , James Morse , Will Deacon , Robin Murphy , Mark Rutland , Marc Zyngier Subject: [PATCH 4.18 249/350] KVM: arm64: Fix caching of host MDCR_EL2 value Date: Sun, 11 Nov 2018 14:21:53 -0800 Message-Id: <20181111221718.455496816@linuxfoundation.org> In-Reply-To: <20181111221707.043394111@linuxfoundation.org> References: <20181111221707.043394111@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: 4.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Mark Rutland commit da5a3ce66b8bb51b0ea8a89f42aac153903f90fb upstream. At boot time, KVM stashes the host MDCR_EL2 value, but only does this when the kernel is not running in hyp mode (i.e. is non-VHE). In these cases, the stashed value of MDCR_EL2.HPMN happens to be zero, which can lead to CONSTRAINED UNPREDICTABLE behaviour. Since we use this value to derive the MDCR_EL2 value when switching to/from a guest, after a guest have been run, the performance counters do not behave as expected. This has been observed to result in accesses via PMXEVTYPER_EL0 and PMXEVCNTR_EL0 not affecting the relevant counters, resulting in events not being counted. In these cases, only the fixed-purpose cycle counter appears to work as expected. Fix this by always stashing the host MDCR_EL2 value, regardless of VHE. Cc: Christopher Dall Cc: James Morse Cc: Will Deacon Cc: stable@vger.kernel.org Fixes: 1e947bad0b63b351 ("arm64: KVM: Skip HYP setup when already running in HYP") Tested-by: Robin Murphy Signed-off-by: Mark Rutland Signed-off-by: Marc Zyngier Signed-off-by: Greg Kroah-Hartman --- virt/kvm/arm/arm.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/virt/kvm/arm/arm.c +++ b/virt/kvm/arm/arm.c @@ -1244,8 +1244,6 @@ static void cpu_init_hyp_mode(void *dumm __cpu_init_hyp_mode(pgd_ptr, hyp_stack_ptr, vector_ptr); __cpu_init_stage2(); - - kvm_arm_init_debug(); } static void cpu_hyp_reset(void) @@ -1269,6 +1267,8 @@ static void cpu_hyp_reinit(void) cpu_init_hyp_mode(NULL); } + kvm_arm_init_debug(); + if (vgic_present) kvm_vgic_init_cpu_hardware(); }