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=-6.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 1903DC76195 for ; Thu, 18 Jul 2019 01:37:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F1BA621852 for ; Thu, 18 Jul 2019 01:37:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732701AbfGRBhS (ORCPT ); Wed, 17 Jul 2019 21:37:18 -0400 Received: from mx1.redhat.com ([209.132.183.28]:2591 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731647AbfGRBhP (ORCPT ); Wed, 17 Jul 2019 21:37:15 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 38CCD30917F1; Thu, 18 Jul 2019 01:37:14 +0000 (UTC) Received: from treble.redhat.com (ovpn-122-211.rdu2.redhat.com [10.10.122.211]) by smtp.corp.redhat.com (Postfix) with ESMTP id BFE005D9CC; Thu, 18 Jul 2019 01:37:12 +0000 (UTC) From: Josh Poimboeuf To: x86@kernel.org Cc: linux-kernel@vger.kernel.org, Peter Zijlstra , Thomas Gleixner , Nick Desaulniers , Arnd Bergmann , Jann Horn , Randy Dunlap , Paolo Bonzini , =?UTF-8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= Subject: [PATCH v2 04/22] x86/kvm: Don't call kvm_spurious_fault() from .fixup Date: Wed, 17 Jul 2019 20:36:39 -0500 Message-Id: <64a9b64d127e87b6920a97afde8e96ea76f6524e.1563413318.git.jpoimboe@redhat.com> In-Reply-To: References: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.41]); Thu, 18 Jul 2019 01:37:14 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 Acked-by: Paolo Bonzini Acked-by: Peter Zijlstra (Intel) --- v2: Fix ____kvm_handle_fault_on_reboot() comment [Paolo] Cc: Paolo Bonzini Cc: Radim Krčmář --- arch/x86/include/asm/kvm_host.h | 34 ++++++++++++++++++--------------- 1 file changed, 19 insertions(+), 15 deletions(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 0cc5b611a113..8282b8d41209 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -1496,25 +1496,29 @@ enum { #define kvm_arch_vcpu_memslots_id(vcpu) ((vcpu)->arch.hflags & HF_SMM_MASK ? 1 : 0) #define kvm_memslots_for_spte_role(kvm, role) __kvm_memslots(kvm, (role).smm) +asmlinkage void __noreturn kvm_spurious_fault(void); + /* * 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. + * Usually after catching the fault we just panic; during reboot + * instead the instruction is ignored. */ -asmlinkage void kvm_spurious_fault(void); - -#define ____kvm_handle_fault_on_reboot(insn, cleanup_insn) \ - "666: " insn "\n\t" \ - "668: \n\t" \ - ".pushsection .fixup, \"ax\" \n" \ - "667: \n\t" \ - cleanup_insn "\n\t" \ - "cmpb $0, kvm_rebooting \n\t" \ - "jne 668b \n\t" \ - __ASM_SIZE(push) " $666b \n\t" \ - "jmp kvm_spurious_fault \n\t" \ - ".popsection \n\t" \ - _ASM_EXTABLE(666b, 667b) +#define ____kvm_handle_fault_on_reboot(insn, cleanup_insn) \ + "666: \n\t" \ + insn "\n\t" \ + "jmp 668f \n\t" \ + "667: \n\t" \ + "call kvm_spurious_fault \n\t" \ + "668: \n\t" \ + ".pushsection .fixup, \"ax\" \n\t" \ + "700: \n\t" \ + cleanup_insn "\n\t" \ + "cmpb $0, kvm_rebooting\n\t" \ + "je 667b \n\t" \ + "jmp 668b \n\t" \ + ".popsection \n\t" \ + _ASM_EXTABLE(666b, 700b) #define __kvm_handle_fault_on_reboot(insn) \ ____kvm_handle_fault_on_reboot(insn, "") -- 2.20.1