From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-11.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 94280C433E1 for ; Wed, 15 Jul 2020 23:00:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7C6332067D for ; Wed, 15 Jul 2020 23:00:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727107AbgGOXAM (ORCPT ); Wed, 15 Jul 2020 19:00:12 -0400 Received: from mga03.intel.com ([134.134.136.65]:1713 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726765AbgGOXAL (ORCPT ); Wed, 15 Jul 2020 19:00:11 -0400 IronPort-SDR: iHMAX7dbH+1DiZw8mqRitIvrUrA+U24ANHKkWNbM6bUqQrSa2FwouM80KZvL0sVsWl+em9zSi+ HJkglCgnaC/A== X-IronPort-AV: E=McAfee;i="6000,8403,9683"; a="149274296" X-IronPort-AV: E=Sophos;i="5.75,357,1589266800"; d="scan'208";a="149274296" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by orsmga103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 15 Jul 2020 16:00:09 -0700 IronPort-SDR: wabWivlgfsZ89og+8FO6XfFmkaajLr8T24U6dOGKCshdczPg5lcuO8WfrxCgC0KZb0x4ywDy1v LJI2s/3cyTXQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.75,357,1589266800"; d="scan'208";a="486406812" Received: from sjchrist-coffee.jf.intel.com (HELO linux.intel.com) ([10.54.74.152]) by fmsmga005.fm.intel.com with ESMTP; 15 Jul 2020 16:00:09 -0700 Date: Wed, 15 Jul 2020 16:00:08 -0700 From: Sean Christopherson To: Mohammed Gamal Cc: kvm@vger.kernel.org, pbonzini@redhat.com, linux-kernel@vger.kernel.org, vkuznets@redhat.com, wanpengli@tencent.com, jmattson@google.com, joro@8bytes.org Subject: Re: [PATCH v3 7/9] KVM: VMX: Add guest physical address check in EPT violation and misconfig Message-ID: <20200715230006.GF12349@linux.intel.com> References: <20200710154811.418214-1-mgamal@redhat.com> <20200710154811.418214-8-mgamal@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200710154811.418214-8-mgamal@redhat.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Fri, Jul 10, 2020 at 05:48:09PM +0200, Mohammed Gamal wrote: > Check guest physical address against it's maximum physical memory. If > the guest's physical address exceeds the maximum (i.e. has reserved bits > set), inject a guest page fault with PFERR_RSVD_MASK set. > > This has to be done both in the EPT violation and page fault paths, as > there are complications in both cases with respect to the computation > of the correct error code. > > For EPT violations, unfortunately the only possibility is to emulate, > because the access type in the exit qualification might refer to an > access to a paging structure, rather than to the access performed by > the program. > > Trapping page faults instead is needed in order to correct the error code, > but the access type can be obtained from the original error code and > passed to gva_to_gpa. The corrections required in the error code are > subtle. For example, imagine that a PTE for a supervisor page has a reserved > bit set. On a supervisor-mode access, the EPT violation path would trigger. > However, on a user-mode access, the processor will not notice the reserved > bit and not include PFERR_RSVD_MASK in the error code. > > Co-developed-by: Mohammed Gamal > Signed-off-by: Paolo Bonzini > --- > arch/x86/kvm/vmx/vmx.c | 24 +++++++++++++++++++++--- > arch/x86/kvm/vmx/vmx.h | 3 ++- > 2 files changed, 23 insertions(+), 4 deletions(-) > > diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c > index 770b090969fb..de3f436b2d32 100644 > --- a/arch/x86/kvm/vmx/vmx.c > +++ b/arch/x86/kvm/vmx/vmx.c > @@ -4790,9 +4790,15 @@ static int handle_exception_nmi(struct kvm_vcpu *vcpu) > > if (is_page_fault(intr_info)) { > cr2 = vmx_get_exit_qual(vcpu); > - /* EPT won't cause page fault directly */ > - WARN_ON_ONCE(!vcpu->arch.apf.host_apf_flags && enable_ept); > - return kvm_handle_page_fault(vcpu, error_code, cr2, NULL, 0); > + if (enable_ept && !vcpu->arch.apf.host_apf_flags) { > + /* > + * EPT will cause page fault only if we need to > + * detect illegal GPAs. > + */ > + kvm_fixup_and_inject_pf_error(vcpu, cr2, error_code); This splats when running the PKU unit test, although the test still passed. I haven't yet spent the brain power to determine if this is a benign warning, i.e. simply unexpected, or if permission_fault() fault truly can't handle PK faults. WARNING: CPU: 25 PID: 5465 at arch/x86/kvm/mmu.h:197 paging64_walk_addr_generic+0x594/0x750 [kvm] Hardware name: Intel Corporation WilsonCity/WilsonCity, BIOS WLYDCRB1.SYS.0014.D62.2001092233 01/09/2020 RIP: 0010:paging64_walk_addr_generic+0x594/0x750 [kvm] Code: <0f> 0b e9 db fe ff ff 44 8b 43 04 4c 89 6c 24 30 8b 13 41 39 d0 89 RSP: 0018:ff53778fc623fb60 EFLAGS: 00010202 RAX: 0000000000000001 RBX: ff53778fc623fbf0 RCX: 0000000000000007 RDX: 0000000000000001 RSI: 0000000000000002 RDI: ff4501efba818000 RBP: 0000000000000020 R08: 0000000000000005 R09: 00000000004000e7 R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000007 R13: ff4501efba818388 R14: 10000000004000e7 R15: 0000000000000000 FS: 00007f2dcf31a700(0000) GS:ff4501f1c8040000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 0000001dea475005 CR4: 0000000000763ee0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 PKRU: 55555554 Call Trace: paging64_gva_to_gpa+0x3f/0xb0 [kvm] kvm_fixup_and_inject_pf_error+0x48/0xa0 [kvm] handle_exception_nmi+0x4fc/0x5b0 [kvm_intel] kvm_arch_vcpu_ioctl_run+0x911/0x1c10 [kvm] kvm_vcpu_ioctl+0x23e/0x5d0 [kvm] ksys_ioctl+0x92/0xb0 __x64_sys_ioctl+0x16/0x20 do_syscall_64+0x3e/0xb0 entry_SYSCALL_64_after_hwframe+0x44/0xa9 ---[ end trace d17eb998aee991da ]---