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Date: Fri, 12 Nov 2021 09:16:50 -0300 From: Marcelo Tosatti <mtosatti@...hat.com> To: linux-kernel@...r.kernel.org Cc: Nitesh Lal <nilal@...hat.com>, Nicolas Saenz Julienne <nsaenzju@...hat.com>, Frederic Weisbecker <frederic@...nel.org>, Christoph Lameter <cl@...ux.com>, Juri Lelli <juri.lelli@...hat.com>, Peter Zijlstra <peterz@...radead.org>, Alex Belits <abelits@...its.com>, Peter Xu <peterx@...hat.com>, Thomas Gleixner <tglx@...utronix.de>, Daniel Bristot de Oliveira <bristot@...hat.com>, Marcelo Tosatti <mtosatti@...hat.com> Subject: [patch v6 08/10] KVM: x86: process isolation work from VM-entry code path The logic to disable vmstat worker thread, when entering nohz full, does not cover all scenarios. For example, it is possible for the following to happen: References: <20211112121642.693790927@...ora.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 VM-entry code path is an entry point similar to userspace return when task isolation is concerned. Call isolation_exit_to_user_mode before VM-enter. Signed-off-by: Marcelo Tosatti <mtosatti@...hat.com> --- include/linux/entry-kvm.h | 4 +++- kernel/entry/kvm.c | 18 ++++++++++++++---- 2 files changed, 17 insertions(+), 5 deletions(-) Index: linux-2.6/kernel/entry/kvm.c =================================================================== --- linux-2.6.orig/kernel/entry/kvm.c +++ linux-2.6/kernel/entry/kvm.c @@ -2,8 +2,11 @@ #include <linux/entry-kvm.h> #include <linux/kvm_host.h> +#include <linux/task_isolation.h> -static int xfer_to_guest_mode_work(struct kvm_vcpu *vcpu, unsigned long ti_work) +static int xfer_to_guest_mode_work(struct kvm_vcpu *vcpu, + unsigned long ti_work, + unsigned long tsk_isol_work) { do { int ret; @@ -26,14 +29,20 @@ static int xfer_to_guest_mode_work(struc if (ret) return ret; + if (tsk_isol_work) + isolation_exit_to_user_mode(); + ti_work = READ_ONCE(current_thread_info()->flags); - } while (ti_work & XFER_TO_GUEST_MODE_WORK || need_resched()); + tsk_isol_work = task_isol_has_work(); + } while (ti_work & XFER_TO_GUEST_MODE_WORK || need_resched() || + tsk_isol_work); return 0; } int xfer_to_guest_mode_handle_work(struct kvm_vcpu *vcpu) { unsigned long ti_work; + unsigned long tsk_isol_work; /* * This is invoked from the outer guest loop with interrupts and @@ -44,9 +53,10 @@ int xfer_to_guest_mode_handle_work(struc * to disable interrupts here. */ ti_work = READ_ONCE(current_thread_info()->flags); - if (!(ti_work & XFER_TO_GUEST_MODE_WORK)) + tsk_isol_work = task_isol_has_work(); + if (!((ti_work & XFER_TO_GUEST_MODE_WORK) || tsk_isol_work)) return 0; - return xfer_to_guest_mode_work(vcpu, ti_work); + return xfer_to_guest_mode_work(vcpu, ti_work, tsk_isol_work); } EXPORT_SYMBOL_GPL(xfer_to_guest_mode_handle_work); Index: linux-2.6/include/linux/entry-kvm.h =================================================================== --- linux-2.6.orig/include/linux/entry-kvm.h +++ linux-2.6/include/linux/entry-kvm.h @@ -8,6 +8,7 @@ #include <linux/seccomp.h> #include <linux/sched.h> #include <linux/tick.h> +#include <linux/task_isolation.h> /* Transfer to guest mode work */ #ifdef CONFIG_KVM_XFER_TO_GUEST_WORK @@ -76,8 +77,9 @@ static inline void xfer_to_guest_mode_pr static inline bool __xfer_to_guest_mode_work_pending(void) { unsigned long ti_work = READ_ONCE(current_thread_info()->flags); + unsigned long tsk_isol_work = task_isol_has_work(); - return !!(ti_work & XFER_TO_GUEST_MODE_WORK); + return !!((ti_work & XFER_TO_GUEST_MODE_WORK) || tsk_isol_work); } /**
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