From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753502AbaC3X1h (ORCPT ); Sun, 30 Mar 2014 19:27:37 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:36602 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753201AbaC3XZG (ORCPT ); Sun, 30 Mar 2014 19:25:06 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Marcelo Tosatti" , "=?UTF-8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?=" , "Paolo Bonzini" Date: Mon, 31 Mar 2014 00:23:35 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 174/200] KVM: SVM: fix cr8 intercept window In-Reply-To: X-SA-Exim-Connect-IP: 192.168.4.249 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.2.56-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Radim Krčmář commit 596f3142d2b7be307a1652d59e7b93adab918437 upstream. We always disable cr8 intercept in its handler, but only re-enable it if handling KVM_REQ_EVENT, so there can be a window where we do not intercept cr8 writes, which allows an interrupt to disrupt a higher priority task. Fix this by disabling intercepts in the same function that re-enables them when needed. This fixes BSOD in Windows 2008. Signed-off-by: Radim Krčmář Reviewed-by: Marcelo Tosatti Signed-off-by: Paolo Bonzini Signed-off-by: Ben Hutchings --- arch/x86/kvm/svm.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -2904,10 +2904,8 @@ static int cr8_write_interception(struct u8 cr8_prev = kvm_get_cr8(&svm->vcpu); /* instruction emulation calls kvm_set_cr8() */ r = cr_interception(svm); - if (irqchip_in_kernel(svm->vcpu.kvm)) { - clr_cr_intercept(svm, INTERCEPT_CR8_WRITE); + if (irqchip_in_kernel(svm->vcpu.kvm)) return r; - } if (cr8_prev <= kvm_get_cr8(&svm->vcpu)) return r; kvm_run->exit_reason = KVM_EXIT_SET_TPR; @@ -3462,6 +3460,8 @@ static void update_cr8_intercept(struct if (is_guest_mode(vcpu) && (vcpu->arch.hflags & HF_VINTR_MASK)) return; + clr_cr_intercept(svm, INTERCEPT_CR8_WRITE); + if (irr == -1) return;