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=-8.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=ham 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 DA5DAC7618F for ; Mon, 15 Jul 2019 12:40:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B7ABC2067C for ; Mon, 15 Jul 2019 12:40:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730065AbfGOMkc (ORCPT ); Mon, 15 Jul 2019 08:40:32 -0400 Received: from mx1.redhat.com ([209.132.183.28]:41312 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728933AbfGOMkc (ORCPT ); Mon, 15 Jul 2019 08:40:32 -0400 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 609E185A03; Mon, 15 Jul 2019 12:40:31 +0000 (UTC) Received: from treble (ovpn-120-170.rdu2.redhat.com [10.10.120.170]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 2EB3760C05; Mon, 15 Jul 2019 12:40:27 +0000 (UTC) Date: Mon, 15 Jul 2019 07:40:25 -0500 From: Josh Poimboeuf To: Paolo Bonzini Cc: x86@kernel.org, linux-kernel@vger.kernel.org, Peter Zijlstra , Thomas Gleixner , Nick Desaulniers , Arnd Bergmann , Jann Horn , Randy Dunlap , Radim =?utf-8?B?S3LEjW3DocWZ?= Subject: Re: [PATCH 04/22] x86/kvm: Don't call kvm_spurious_fault() from .fixup Message-ID: <20190715124025.prcetv24oyjnuvip@treble> References: <1f37a9e42732c224bc5299dbc827b4101c9deb22.1563150885.git.jpoimboe@redhat.com> <07b8513a-d8f7-f8cf-daf6-83a80ade987a@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <07b8513a-d8f7-f8cf-daf6-83a80ade987a@redhat.com> User-Agent: NeoMutt/20180716 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.26]); Mon, 15 Jul 2019 12:40:31 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jul 15, 2019 at 11:07:28AM +0200, Paolo Bonzini wrote: > On 15/07/19 02:36, Josh Poimboeuf wrote: > > After making a change to improve objtool's sibling call detection, it > > started showing the following warning: > > > > arch/x86/kvm/vmx/nested.o: warning: objtool: .fixup+0x15: sibling call from callable instruction with modified stack frame > > > > The problem is the ____kvm_handle_fault_on_reboot() macro. It does a > > fake call by pushing a fake RIP and doing a jump. That tricks the > > unwinder into printing the function which triggered the exception, > > rather than the .fixup code. > > > > Instead of the hack to make it look like the original function made the > > call, just change the macro so that the original function actually does > > make the call. This allows removal of the hack, and also makes objtool > > happy. > > > > I triggered a vmx instruction exception and verified that the stack > > trace is still sane: > > > > kernel BUG at arch/x86/kvm/x86.c:358! > > invalid opcode: 0000 [#1] SMP PTI > > CPU: 28 PID: 4096 Comm: qemu-kvm Not tainted 5.2.0+ #16 > > Hardware name: Lenovo THINKSYSTEM SD530 -[7X2106Z000]-/-[7X2106Z000]-, BIOS -[TEE113Z-1.00]- 07/17/2017 > > RIP: 0010:kvm_spurious_fault+0x5/0x10 > > Code: 00 00 00 00 00 8b 44 24 10 89 d2 45 89 c9 48 89 44 24 10 8b 44 24 08 48 89 44 24 08 e9 d4 40 22 00 0f 1f 40 00 0f 1f 44 00 00 <0f> 0b 66 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 41 55 49 89 fd 41 > > RSP: 0018:ffffbf91c683bd00 EFLAGS: 00010246 > > RAX: 000061f040000000 RBX: ffff9e159c77bba0 RCX: ffff9e15a5c87000 > > RDX: 0000000665c87000 RSI: ffff9e15a5c87000 RDI: ffff9e159c77bba0 > > RBP: 0000000000000000 R08: 0000000000000000 R09: ffff9e15a5c87000 > > R10: 0000000000000000 R11: fffff8f2d99721c0 R12: ffff9e159c77bba0 > > R13: ffffbf91c671d960 R14: ffff9e159c778000 R15: 0000000000000000 > > FS: 00007fa341cbe700(0000) GS:ffff9e15b7400000(0000) knlGS:0000000000000000 > > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > CR2: 00007fdd38356804 CR3: 00000006759de003 CR4: 00000000007606e0 > > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > > PKRU: 55555554 > > Call Trace: > > loaded_vmcs_init+0x4f/0xe0 > > alloc_loaded_vmcs+0x38/0xd0 > > vmx_create_vcpu+0xf7/0x600 > > kvm_vm_ioctl+0x5e9/0x980 > > ? __switch_to_asm+0x40/0x70 > > ? __switch_to_asm+0x34/0x70 > > ? __switch_to_asm+0x40/0x70 > > ? __switch_to_asm+0x34/0x70 > > ? free_one_page+0x13f/0x4e0 > > do_vfs_ioctl+0xa4/0x630 > > ksys_ioctl+0x60/0x90 > > __x64_sys_ioctl+0x16/0x20 > > do_syscall_64+0x55/0x1c0 > > entry_SYSCALL_64_after_hwframe+0x44/0xa9 > > RIP: 0033:0x7fa349b1ee5b > > > > Signed-off-by: Josh Poimboeuf > > --- > > Cc: Paolo Bonzini > > Cc: Radim Krčmář > > --- > > arch/x86/include/asm/kvm_host.h | 33 ++++++++++++++++++--------------- > > 1 file changed, 18 insertions(+), 15 deletions(-) > > > > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h > > index 0cc5b611a113..af7e18c05f98 100644 > > --- a/arch/x86/include/asm/kvm_host.h > > +++ b/arch/x86/include/asm/kvm_host.h > > @@ -1499,22 +1499,25 @@ enum { > > /* > > * Hardware virtualization extension instructions may fault if a > > * reboot turns off virtualization while processes are running. > > - * Trap the fault and ignore the instruction if that happens. > > + * If that happens, trap the fault and panic (unless we're rebooting). > > Not sure the comment is better than before, but apar from that The previous comment didn't seem to match the code, since we only ignore the instruction if we're rebooting. > Acked-by: Paolo Bonzini Thanks! -- Josh