From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4DD67286B2 for ; Thu, 4 Jan 2024 16:54:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="VO0LKzHB" Received: by smtp.kernel.org (Postfix) with ESMTPS id C4539C433C9 for ; Thu, 4 Jan 2024 16:54:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1704387250; bh=oWCOQlkv0fcdWmMXkx+YFpSZaglqfWVO7zyJ9vTsnZY=; h=From:To:Subject:Date:In-Reply-To:References:From; b=VO0LKzHBaty6YEAK3862iCPZCQ8PHsm86SIWeSo75m6chENW22J9rGAiNTEJm7Pi8 2KbB6PPwF/arIpnwHz9WS+5d0wa3LmId6OKxC24D7erGdYorWDea8D5t4wQrGvlKgJ S1ef28MAQeKeYfmuVGpSRoF9ULo9MPNcRa+B+12f6KTgNRO4wswobesImzh3Ebf9Rl f+e86HY71MakGs1KKKAkvRnOJu/YuG4vaT9xGFy6YNvcwa+o7kBJOgKmlSJ/l9YzvG HG/XM7NVR+f45xtwc/BiEIHjMofuM3KnIeHNjGT5H/RMq/L9LwdQTHdsTjqD30VSmp s6X/X20ZJUMCQ== Received: by aws-us-west-2-korg-bugzilla-1.web.codeaurora.org (Postfix, from userid 48) id ACC5AC53BD3; Thu, 4 Jan 2024 16:54:10 +0000 (UTC) From: bugzilla-daemon@kernel.org To: kvm@vger.kernel.org Subject: [Bug 218339] kernel goes unresponsive if single-stepping over an instruction which writes to an address for which a hardware read/write watchpoint has been set Date: Thu, 04 Jan 2024 16:54:10 +0000 X-Bugzilla-Reason: None X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: AssignedTo virtualization_kvm@kernel-bugs.osdl.org X-Bugzilla-Product: Virtualization X-Bugzilla-Component: kvm X-Bugzilla-Version: unspecified X-Bugzilla-Keywords: X-Bugzilla-Severity: normal X-Bugzilla-Who: seanjc@google.com X-Bugzilla-Status: NEW X-Bugzilla-Resolution: X-Bugzilla-Priority: P3 X-Bugzilla-Assigned-To: virtualization_kvm@kernel-bugs.osdl.org X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: Message-ID: In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Bugzilla-URL: https://bugzilla.kernel.org/ Auto-Submitted: auto-generated Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 https://bugzilla.kernel.org/show_bug.cgi?id=3D218339 --- Comment #1 from Sean Christopherson (seanjc@google.com) --- On Thu, Jan 04, 2024, bugzilla-daemon@kernel.org wrote: > https://bugzilla.kernel.org/show_bug.cgi?id=3D218339 >=20 > Bug ID: 218339 > Summary: kernel goes unresponsive if single-stepping over an > instruction which writes to an address for which a > hardware read/write watchpoint has been set > Product: Virtualization > Version: unspecified > Hardware: All > OS: Linux > Status: NEW > Severity: normal > Priority: P3 > Component: kvm > Assignee: virtualization_kvm@kernel-bugs.osdl.org > Reporter: anthony.louis.eden@gmail.com > Regression: No >=20 > In a debian QEMU/KVM virtual machine, run `gdb` on any executable (e.g. > `/usr/bin/ls`). Run the program by typing `starti`. Proceed to `_dl_start` > (i.e. `break _dl_start`, `continue`). When you get there disassemble the > function (i.e. `disas`). Find an instruction that's going to be executed = for > which you can compute the address in memory it will write to. Run the pro= gram > to that instruction (i.e. `break *0xINSN`, `continue`). When you're on th= at > instruction, set a read/write watchpoint on the address it will write to, > then > single-step (i.e. `stepi`) and the kernel will go unresponsive. By "the kernel", I assume you mean the guest kernel? > >(gdb) x/1i $pc > >=3D> 0x7ffff7fe6510 <_dl_start+48>: mov %rdi,-0x88(%rbp) > >(gdb) x/1wx $rbp-0x88 > >0x7fffffffec28: 0x00000000 > >(gdb) awatch *0x7fffffffec28 > >Hardware access (read/write) watchpoint 2: *0x7fffffffec28 > >(gdb) stepi >=20 >=20 > Looking with `journalctl`, I cannot find anything printed to dmesg. >=20 > The kernel of the guest inside the virtual machine is Debian 6.1.0-15-amd= 64. > The kernel of the host running qemu-system-x86_64 is Archlinux 6.6.7-arch= 1-1. > gdb is version 13.1. Is this a regression or something that has always been broken? I.e. did th= is work on previous host kernels? --=20 You may reply to this email to add a comment. You are receiving this mail because: You are watching the assignee of the bug.=