From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 404VjW5KCZzF1W3 for ; Mon, 19 Mar 2018 20:13:35 +1100 (AEDT) Received: from pps.filterd (m0098394.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id w2J9Andr083534 for ; Mon, 19 Mar 2018 05:13:33 -0400 Received: from e06smtp14.uk.ibm.com (e06smtp14.uk.ibm.com [195.75.94.110]) by mx0a-001b2d01.pphosted.com with ESMTP id 2gt2jgxmht-1 (version=TLSv1.2 cipher=AES256-SHA256 bits=256 verify=NOT) for ; Mon, 19 Mar 2018 05:13:33 -0400 Received: from localhost by e06smtp14.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Mon, 19 Mar 2018 09:13:30 -0000 From: "Naveen N. Rao" To: Steven Rostedt , Michael Ellerman , Paul Mackerras Cc: linuxppc-dev@lists.ozlabs.org, Benjamin Herrenschmidt , Anton Blanchard , Nicholas Piggin , sathnaga@linux.vnet.ibm.com Subject: [PATCH 2/2] powerpc64/ftrace: Disable ftrace during kvm guest entry/exit Date: Mon, 19 Mar 2018 14:43:01 +0530 In-Reply-To: References: In-Reply-To: References: Message-Id: List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , During guest entry/exit, we switch over to/from the guest MMU context. While doing so, we set our state to KVM_GUEST_MODE_HOST_HV to note down the fact that we cannot take any exceptions in the hypervisor code. Since ftrace may be enabled and since it can result in us taking a trap, disable ftrace by setting paca->ftrace_disabled. Once we exit the guest and restore host MMU context, we re-enable ftrace. Signed-off-by: Naveen N. Rao --- arch/powerpc/kvm/book3s_hv_rmhandlers.S | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S index f31f357b8c5a..9292087adb68 100644 --- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S +++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S @@ -600,6 +600,10 @@ kvmppc_hv_entry: /* Save R1 in the PACA */ std r1, HSTATE_HOST_R1(r13) + /* Disable ftrace since we can't take a trap any more */ + li r6, 1 + stb r6, PACA_FTRACE_DISABLED(r13) + li r6, KVM_GUEST_MODE_HOST_HV stb r6, HSTATE_IN_GUEST(r13) @@ -2048,6 +2052,8 @@ END_MMU_FTR_SECTION_IFSET(MMU_FTR_TYPE_RADIX) /* Unset guest mode */ li r0, KVM_GUEST_MODE_NONE stb r0, HSTATE_IN_GUEST(r13) + li r0, 0 + stb r0, PACA_FTRACE_DISABLED(r13) ld r0, SFS+PPC_LR_STKOFF(r1) addi r1, r1, SFS @@ -3379,6 +3385,8 @@ END_MMU_FTR_SECTION_IFSET(MMU_FTR_TYPE_RADIX) ld r8, KVM_HOST_LPCR(r10) mtspr SPRN_LPCR, r8 isync + li r0, 0 + stb r0, PACA_FTRACE_DISABLED(r13) li r0, KVM_GUEST_MODE_NONE stb r0, HSTATE_IN_GUEST(r13) -- 2.16.2