lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Message-ID: <871qbud5f9.fsf@email.froward.int.ebiederm.org> Date: Sat, 09 Dec 2023 22:53:30 -0600 From: "Eric W. Biederman" <ebiederm@...ssion.com> To: "Gowans, James" <jgowans@...zon.com> Cc: "pbonzini@...hat.com" <pbonzini@...hat.com>, "Graf (AWS), Alexander" <graf@...zon.de>, "seanjc@...gle.com" <seanjc@...gle.com>, Schönherr, Jan H. <jschoenh@...zon.de>, "yuzenghui@...wei.com" <yuzenghui@...wei.com>, "atishp@...shpatra.org" <atishp@...shpatra.org>, "kvm-riscv@...ts.infradead.org" <kvm-riscv@...ts.infradead.org>, "james.morse@....com" <james.morse@....com>, "suzuki.poulose@....com" <suzuki.poulose@....com>, "oliver.upton@...ux.dev" <oliver.upton@...ux.dev>, "chenhuacai@...nel.org" <chenhuacai@...nel.org>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, "kvmarm@...ts.linux.dev" <kvmarm@...ts.linux.dev>, "maz@...nel.org" <maz@...nel.org>, "kvm@...r.kernel.org" <kvm@...r.kernel.org>, "aleksandar.qemu.devel@...il.com" <aleksandar.qemu.devel@...il.com>, "anup@...infault.org" <anup@...infault.org>, "kexec@...ts.infradead.org" <kexec@...ts.infradead.org> Subject: Re: [PATCH v2 1/2] KVM: Use syscore_ops instead of reboot_notifier to hook restart/shutdown "Gowans, James" <jgowans@...zon.com> writes: > Hi Sean, > > Blast from the past but I've just been bitten by this patch when > rebasing across v6.4. > > On Fri, 2023-05-12 at 16:31 -0700, Sean Christopherson wrote: >> Use syscore_ops.shutdown to disable hardware virtualization during a >> reboot instead of using the dedicated reboot_notifier so that KVM disables >> virtualization _after_ system_state has been updated. This will allow >> fixing a race in KVM's handling of a forced reboot where KVM can end up >> enabling hardware virtualization between kernel_restart_prepare() and >> machine_restart(). > > The issue is that, AFAICT, the syscore_ops.shutdown are not called when > doing a kexec. Reboot notifiers are called across kexec via: > > kernel_kexec > kernel_restart_prepare > blocking_notifier_call_chain > kvm_reboot > > So after this patch, KVM is not shutdown during kexec; if hardware virt > mode is enabled then the kexec hangs in exactly the same manner as you > describe with the reboot. kernel_restart_prepare calls device_shutdown. Which should call all of the shutdown operations. This has been the way the code has been structured since December 2005. > Some specific shutdown callbacks, for example IOMMU, HPET, IRQ, etc are > called in native_machine_shutdown, but KVM is not one of these. > > Thoughts on possible ways to fix this: > a) go back to reboot notifiers > b) get kexec to call syscore_shutdown() to invoke all of these callbacks > c) Add a KVM-specific callback to native_machine_shutdown(); we only > need this for Intel x86, right? > > My slight preference is towards adding syscore_shutdown() to kexec, but > I'm not sure that's feasible. Adding kexec maintainers for input. Why isn't device_suthdown calling syscore_shutdown? What problem are you running into with your rebase that worked with reboot notifiers that is not working with syscore_shutdown? Eric
Powered by blists - more mailing lists