From: Thomas Gleixner <tglx@linutronix.de>
To: LKML <linux-kernel@vger.kernel.org>
Cc: x86@kernel.org, Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@kernel.org>,
Sebastian Siewior <bigeasy@linutronix.de>,
Anna-Maria Gleixner <anna-maria@linutronix.de>,
Steven Rostedt <rostedt@goodmis.org>,
Julia Cartwright <julia@ni.com>,
Paul McKenney <paulmck@linux.vnet.ibm.com>,
Frederic Weisbecker <fweisbec@gmail.com>,
kvm@vger.kernel.org, Radim Krcmar <rkrcmar@redhat.com>,
Paolo Bonzini <pbonzini@redhat.com>,
Oleg Nesterov <oleg@redhat.com>,
John Stultz <john.stultz@linaro.org>,
Andy Lutomirski <luto@kernel.org>,
"Paul E. McKenney" <paulmck@linux.ibm.com>
Subject: [patch 2/5] x86/kvm: Handle task_work on VMENTER/EXIT
Date: Thu, 01 Aug 2019 16:32:52 +0200 [thread overview]
Message-ID: <20190801143657.887648487@linutronix.de> (raw)
In-Reply-To: 20190801143250.370326052@linutronix.de
TIF_NOTITY_RESUME is evaluated on return to user space along with other TIF
flags.
>From the kernels point of view a VMENTER is more or less equivalent to
return to user space which means that at least a subset of TIF flags needs
to be evaluated and handled.
Currently KVM handles only TIF_SIGPENDING and TIF_NEED_RESCHED, but
TIF_NOTIFY_RESUME is ignored. So pending task_work etc, is completely
ignored until the vCPU thread actually goes all the way back into
userspace/qemu.
Use the newly provided notify_resume_pending() and
tracehook_handle_notify_resume() to solve this similar to the existing
handling of SIGPENDING.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: kvm@vger.kernel.org
Cc: Radim Krcmar <rkrcmar@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
---
arch/x86/kvm/x86.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -52,6 +52,7 @@
#include <linux/irqbypass.h>
#include <linux/sched/stat.h>
#include <linux/sched/isolation.h>
+#include <linux/tracehook.h>
#include <linux/mem_encrypt.h>
#include <trace/events/kvm.h>
@@ -7972,7 +7973,8 @@ static int vcpu_enter_guest(struct kvm_v
kvm_x86_ops->sync_pir_to_irr(vcpu);
if (vcpu->mode == EXITING_GUEST_MODE || kvm_request_pending(vcpu)
- || need_resched() || signal_pending(current)) {
+ || need_resched() || signal_pending(current)
+ || notify_resume_pending()) {
vcpu->mode = OUTSIDE_GUEST_MODE;
smp_wmb();
local_irq_enable();
@@ -8172,6 +8174,10 @@ static int vcpu_run(struct kvm_vcpu *vcp
++vcpu->stat.signal_exits;
break;
}
+
+ if (notify_resume_pending())
+ tracehook_handle_notify_resume();
+
if (need_resched()) {
srcu_read_unlock(&kvm->srcu, vcpu->srcu_idx);
cond_resched();
next prev parent reply other threads:[~2019-08-01 14:38 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-01 14:32 [patch 0/5] posix-cpu-timers: Move expiry into task work context Thomas Gleixner
2019-08-01 14:32 ` [patch 1/5] tracehook: Provide TIF_NOTIFY_RESUME handling for KVM Thomas Gleixner
2019-08-01 14:48 ` Peter Zijlstra
2019-08-01 15:10 ` Thomas Gleixner
2019-08-01 17:02 ` Andy Lutomirski
2019-08-01 14:32 ` Thomas Gleixner [this message]
2019-08-01 16:24 ` [patch 2/5] x86/kvm: Handle task_work on VMENTER/EXIT Oleg Nesterov
2019-08-01 18:34 ` Thomas Gleixner
2019-08-01 21:35 ` Sean Christopherson
2019-08-01 21:44 ` Peter Zijlstra
2019-08-01 21:44 ` Thomas Gleixner
2019-08-01 21:47 ` Thomas Gleixner
2019-08-02 21:35 ` Paolo Bonzini
2019-08-02 22:22 ` Thomas Gleixner
2019-08-02 22:39 ` Andy Lutomirski
2019-08-02 12:04 ` Oleg Nesterov
2019-08-01 14:32 ` [patch 3/5] posix-cpu-timers: Split run_posix_cpu_timers() Thomas Gleixner
2019-08-01 14:32 ` [patch 4/5] posix-cpu-timers: Defer timer handling to task_work Thomas Gleixner
2019-08-01 14:51 ` Peter Zijlstra
2019-08-01 15:10 ` Thomas Gleixner
2019-08-01 15:39 ` Oleg Nesterov
2019-08-01 18:41 ` Thomas Gleixner
2019-08-01 14:32 ` [patch 5/5] x86: Select POSIX_CPU_TIMERS_TASK_WORK Thomas Gleixner
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