From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ozlabs.org (ozlabs.org [103.22.144.67]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 7A8971A000A for ; Fri, 4 Jul 2014 12:16:50 +1000 (EST) Message-ID: <1404440209.18906.1.camel@concordia> Subject: Re: [PATCH 1/3] powerpc/kvm: Remove redundant save of SIER AND MMCR2 From: Michael Ellerman To: Joel Stanley Date: Fri, 04 Jul 2014 12:16:49 +1000 In-Reply-To: <1404367956-19515-2-git-send-email-joel@jms.id.au> References: <1404367956-19515-1-git-send-email-joel@jms.id.au> <1404367956-19515-2-git-send-email-joel@jms.id.au> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Cc: paulus@samba.org, linuxppc-dev@lists.ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Thu, 2014-07-03 at 15:42 +0930, Joel Stanley wrote: > These two registers are already saved in the block above. Aside from > being unnecessary, by the time we get down to the second save location > r8 no longer contains MMCR2, so we are clobbering the saved value with > PMC5. MMCR2 primarily consists of counter freeze bits. So restoring the value of PMC5 into MMCR2 will most likely have the effect of freezing counters. Fixes: 72cde5a88d37 ("KVM: PPC: Book3S HV: Save/restore host PMU registers that are new in POWER8") Cc: stable@vger.kernel.org With the above added: Acked-by: Michael Ellerman cheers