From: Miroslav Benes <mbenes@suse.cz>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: LKML <linux-kernel@vger.kernel.org>,
x86@kernel.org, Peter Zijlstra <peterz@infradead.org>,
Andy Lutomirski <luto@kernel.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Marc Zyngier <maz@kernel.org>,
Paolo Bonzini <pbonzini@redhat.com>,
kvm@vger.kernel.org, linux-arch@vger.kernel.org,
live-patching@vger.kernel.org
Subject: Re: [RFC patch 14/15] workpending: Provide infrastructure for work before entering a guest
Date: Thu, 26 Sep 2019 13:35:04 +0200 (CEST) [thread overview]
Message-ID: <alpine.LSU.2.21.1909261324580.3740@pobox.suse.cz> (raw)
In-Reply-To: <20190919150809.860645841@linutronix.de>
> --- a/include/linux/entry-common.h
> +++ b/include/linux/entry-common.h
[...]
> +#define EXIT_TO_GUESTMODE_WORK \
> + (_TIF_NEED_RESCHED | _TIF_SIGPENDING | _TIF_NOTIFY_RESUME | \
> + ARCH_EXIT_TO_GUESTMODE_WORK)
[...]
> --- a/kernel/entry/common.c
> +++ b/kernel/entry/common.c
>
> +int core_exit_to_guestmode_work(struct kvm *kvm, struct kvm_vcpu *vcpu,
> + unsigned long ti_work)
> +{
> + /*
> + * Before returning to guest mode handle all pending work
> + */
> + if (ti_work & _TIF_SIGPENDING) {
> + vcpu->run->exit_reason = KVM_EXIT_INTR;
> + vcpu->stat.signal_exits++;
> + return -EINTR;
> + }
> +
> + if (ti_work & _TIF_NEED_RESCHED) {
> + srcu_read_unlock(&kvm->srcu, vcpu->srcu_idx);
> + schedule();
> + vcpu->srcu_idx = srcu_read_lock(&kvm->srcu);
> + }
> +
> + if (ti_work & _TIF_PATCH_PENDING) {
> + srcu_read_unlock(&kvm->srcu, vcpu->srcu_idx);
> + klp_update_patch_state(current);
> + vcpu->srcu_idx = srcu_read_lock(&kvm->srcu);
> + }
If I am reading the code correctly, _TIF_PATCH_PENDING is not a part of
EXIT_TO_GUESTMODE_WORK, so the handling code here would not be called on
any arch as of now.
I also think that _TIF_PATCH_PENDING must not be handled here generally.
It could break consistency guarantees when live patching KVM (and we do
that from time to time).
Adding live-patching ML to CC.
Miroslav
> + if (ti_work & _TIF_NOTIFY_RESUME) {
> + srcu_read_unlock(&kvm->srcu, vcpu->srcu_idx);
> + clear_thread_flag(TIF_NOTIFY_RESUME);
> + tracehook_notify_resume(NULL);
> + vcpu->srcu_idx = srcu_read_lock(&kvm->srcu);
> + }
> +
> + /* Any extra architecture specific work */
> + return arch_exit_to_guestmode_work(kvm, vcpu, ti_work);
> +}
next prev parent reply other threads:[~2019-09-26 11:35 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-19 15:03 [RFC patch 00/15] entry: Provide generic implementation for host and guest entry/exit work Thomas Gleixner
2019-09-19 15:03 ` [RFC patch 01/15] entry: Provide generic syscall entry functionality Thomas Gleixner
2019-09-20 23:38 ` Andy Lutomirski
2019-10-20 11:49 ` Thomas Gleixner
2019-09-23 9:05 ` Mike Rapoport
2019-09-19 15:03 ` [RFC patch 02/15] x86/entry: Remove _TIF_NOHZ from _TIF_WORK_SYSCALL_ENTRY Thomas Gleixner
2019-09-20 23:39 ` Andy Lutomirski
2019-09-23 20:43 ` Thomas Gleixner
2019-09-19 15:03 ` [RFC patch 03/15] x86/entry: Use generic syscall entry function Thomas Gleixner
2019-09-20 23:41 ` Andy Lutomirski
2019-09-23 8:31 ` Peter Zijlstra
2019-09-23 8:40 ` Thomas Gleixner
2019-09-19 15:03 ` [RFC patch 04/15] arm64/entry: " Thomas Gleixner
2019-09-20 12:21 ` Catalin Marinas
2019-09-19 15:03 ` [RFC patch 05/15] entry: Provide generic syscall exit function Thomas Gleixner
2019-09-19 15:03 ` [RFC patch 06/15] x86/entry: Use generic syscall exit functionality Thomas Gleixner
2019-09-19 15:03 ` [RFC patch 07/15] arm64/syscall: Remove obscure flag check Thomas Gleixner
2019-09-20 14:29 ` Catalin Marinas
2019-09-19 15:03 ` [RFC patch 08/15] arm64/syscall: Use generic syscall exit functionality Thomas Gleixner
2019-09-19 15:03 ` [RFC patch 09/15] entry: Provide generic exit to usermode functionality Thomas Gleixner
2019-09-23 8:30 ` Peter Zijlstra
2019-09-19 15:03 ` [RFC patch 10/15] x86/entry: Move irq tracing to C code Thomas Gleixner
2019-09-23 8:47 ` Peter Zijlstra
2019-09-23 10:27 ` Thomas Gleixner
2019-09-23 11:49 ` Peter Zijlstra
2019-09-23 11:55 ` Peter Zijlstra
2019-09-23 12:10 ` Peter Zijlstra
2019-09-23 17:24 ` Andy Lutomirski
2019-09-26 2:59 ` Josh Poimboeuf
2019-09-19 15:03 ` [RFC patch 11/15] x86/entry: Use generic exit to usermode Thomas Gleixner
2019-09-19 15:03 ` [RFC patch 12/15] arm64/entry: " Thomas Gleixner
2019-09-19 15:03 ` [RFC patch 13/15] arm64/entry: Move FPU restore out of exit_to_usermode() loop Thomas Gleixner
2019-09-19 15:03 ` [RFC patch 14/15] workpending: Provide infrastructure for work before entering a guest Thomas Gleixner
2019-09-19 15:40 ` Paolo Bonzini
2019-09-20 11:48 ` Thomas Gleixner
2019-09-23 18:17 ` Andy Lutomirski
2019-09-26 11:35 ` Miroslav Benes [this message]
2019-09-19 15:03 ` [RFC patch 15/15] x86/kvm: Use GENERIC_EXIT_WORKPENDING Thomas Gleixner
2019-09-19 15:40 ` Paolo Bonzini
2019-09-20 15:12 ` [RFC patch 00/15] entry: Provide generic implementation for host and guest entry/exit work Mark Rutland
2019-09-23 20:50 ` Thomas Gleixner
2019-09-23 18:18 ` Andy Lutomirski
2019-09-24 6:50 ` Christian Borntraeger
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