From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756070Ab1HaVsY (ORCPT ); Wed, 31 Aug 2011 17:48:24 -0400 Received: from mx1.redhat.com ([209.132.183.28]:59917 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755751Ab1HaVsX (ORCPT ); Wed, 31 Aug 2011 17:48:23 -0400 From: Igor Mammedov To: linux-kernel@vger.kernel.org Cc: xen-devel@lists.xensource.com, jeremy@goop.org, konrad.wilk@oracle.com Subject: [PATCH] xen: x86_32: do not enable iterrupts when returning from exception in interrupt context Date: Thu, 1 Sep 2011 01:47:18 +0200 Message-Id: <1314834438-3181-1-git-send-email-imammedo@redhat.com> In-Reply-To: <20110829194633.GB16530@dumpdata.com> References: <20110829194633.GB16530@dumpdata.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org If vmalloc page_fault happens inside of interrupt handler with interrupts disabled then on exit path from exception handler when there is no pending interrupts, the following code (arch/x86/xen/xen-asm_32.S:112): cmpw $0x0001, XEN_vcpu_info_pending(%eax) sete XEN_vcpu_info_mask(%eax) will enable interrupts even if they has been previously disabled according to eflags from the bounce frame (arch/x86/xen/xen-asm_32.S:99) testb $X86_EFLAGS_IF>>8, 8+1+ESP_OFFSET(%esp) setz XEN_vcpu_info_mask(%eax) Solution is in setting XEN_vcpu_info_mask only when it should be set according to cmpw $0x0001, XEN_vcpu_info_pending(%eax) but not clearing it if there isn't any pending events. Signed-off-by: Igor Mammedov --- arch/x86/xen/xen-asm_32.S | 6 +++++- 1 files changed, 5 insertions(+), 1 deletions(-) diff --git a/arch/x86/xen/xen-asm_32.S b/arch/x86/xen/xen-asm_32.S index 22a2093..313dca7 100644 --- a/arch/x86/xen/xen-asm_32.S +++ b/arch/x86/xen/xen-asm_32.S @@ -113,10 +113,14 @@ xen_iret_start_crit: /* * If there's something pending, mask events again so we can - * jump back into xen_hypervisor_callback + * jump back into xen_hypervisor_callback. Otherwise do not + * touch XEN_vcpu_info_mask. */ + jne ignore_vcpu_info_mask sete XEN_vcpu_info_mask(%eax) +ignore_vcpu_info_mask: + popl %eax /* -- 1.7.1