Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752291AbdLGIaP (ORCPT ); Thu, 7 Dec 2017 03:30:15 -0500 Received: from mail-pf0-f196.google.com ([209.85.192.196]:40103 "EHLO mail-pf0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752171AbdLGIaN (ORCPT ); Thu, 7 Dec 2017 03:30:13 -0500 X-Google-Smtp-Source: AGs4zMaLpRB5GJdRraeD8NsQPFmTk4uYxvd+BMcQP31uwgJsqjjm23rXVUvCHMbBNkBizYO8Kyyxdg== From: Wanpeng Li X-Google-Original-From: Wanpeng Li To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: Paolo Bonzini , =?UTF-8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= , Wanpeng Li , Jim Mattson Subject: [PATCH v3] KVM: X86: Fix load RFLAGS w/o the fixed bit Date: Thu, 7 Dec 2017 00:30:08 -0800 Message-Id: <1512635408-11645-1-git-send-email-wanpeng.li@hotmail.com> X-Mailer: git-send-email 2.7.4 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2014 Lines: 67 From: Wanpeng Li *** Guest State *** CR0: actual=0x0000000000000030, shadow=0x0000000060000010, gh_mask=fffffffffffffff7 CR4: actual=0x0000000000002050, shadow=0x0000000000000000, gh_mask=ffffffffffffe871 CR3 = 0x00000000fffbc000 RSP = 0x0000000000000000 RIP = 0x0000000000000000 RFLAGS=0x00000000 DR7 = 0x0000000000000400 ^^^^^^^^^^ The failed vmentry is triggered by the following testcase when ept=Y: #include #include #include #include #include #include #include long r[5]; int main() { r[2] = open("/dev/kvm", O_RDONLY); r[3] = ioctl(r[2], KVM_CREATE_VM, 0); r[4] = ioctl(r[3], KVM_CREATE_VCPU, 7); struct kvm_regs regs = { .rflags = 0, }; ioctl(r[4], KVM_SET_REGS, ®s); ioctl(r[4], KVM_RUN, 0); } X86 RFLAGS bit 1 is fixed set, userspace can simply clearing bit 1 of RFLAGS with KVM_SET_REGS ioctl which results in vmentry fails. This patch fixes it by oring X86_EFLAGS_FIXED during ioctl. Suggested-by: Jim Mattson Reviewed-by: David Hildenbrand Cc: Paolo Bonzini Cc: Radim Krčmář Cc: Jim Mattson Signed-off-by: Wanpeng Li --- v2 -> v3: * move Oring X86_EFLAGS_FIXED to kvm_arch_vcpu_ioctl_set_regs v1 -> v2: * Oring X86_EFLAGS_FIXED arch/x86/kvm/x86.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index ebe0a3a..0c5d55c 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -7405,7 +7405,7 @@ int kvm_arch_vcpu_ioctl_set_regs(struct kvm_vcpu *vcpu, struct kvm_regs *regs) #endif kvm_rip_write(vcpu, regs->rip); - kvm_set_rflags(vcpu, regs->rflags); + kvm_set_rflags(vcpu, regs->rflags | X86_EFLAGS_FIXED); vcpu->arch.exception.pending = false; -- 2.7.4