KVM Archive on lore.kernel.org
 help / color / Atom feed
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>,
	Oleg Nesterov <oleg@redhat.com>,
	kvm@vger.kernel.org, Radim Krcmar <rkrcmar@redhat.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	John Stultz <john.stultz@linaro.org>,
	Andy Lutomirski <luto@kernel.org>,
	"Paul E. McKenney" <paulmck@linux.ibm.com>
Subject: [patch 1/5] tracehook: Provide TIF_NOTIFY_RESUME handling for KVM
Date: Thu, 01 Aug 2019 16:32:51 +0200
Message-ID: <20190801143657.785902257@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.

Provide notify_resume_pending() and tracehook_handle_notify_resume() so
this can be handled similar to SIGPENDING.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Oleg Nesterov <oleg@redhat.com>
---
 include/linux/tracehook.h |   15 +++++++++++++++
 kernel/task_work.c        |   19 +++++++++++++++++++
 2 files changed, 34 insertions(+)

--- a/include/linux/tracehook.h
+++ b/include/linux/tracehook.h
@@ -163,6 +163,21 @@ static inline void set_notify_resume(str
 #endif
 }
 
+#ifdef CONFIG_HAVE_ARCH_TRACEHOOK
+/**
+ * notify_resume_pending - Check whether current has TIF_NOTIFY_RESUME set
+ */
+static inline bool notify_resume_pending(void)
+{
+	return test_thread_flag(TIF_NOTIFY_RESUME);
+}
+
+void tracehook_handle_notify_resume(void);
+#else
+static inline bool notify_resume_pending(void) { return false; }
+static inline void tracehook_handle_notify_resume(void) { }
+#endif
+
 /**
  * tracehook_notify_resume - report when about to return to user mode
  * @regs:		user-mode registers of @current task
--- a/kernel/task_work.c
+++ b/kernel/task_work.c
@@ -116,3 +116,22 @@ void task_work_run(void)
 		} while (work);
 	}
 }
+
+#ifdef CONFIG_HAVE_ARCH_TRACEHOOK
+/**
+ * tracehook_handle_notify_resume - Notify resume handling for virt
+ *
+ * Called with interrupts and preemption enabled from VMENTER/EXIT.
+ */
+void tracehook_handle_notify_resume(void)
+{
+	local_irq_disable();
+	while (test_and_clear_thread_flag(TIF_NOTIFY_RESUME)) {
+		local_irq_enable();
+		tracehook_notify_resume(NULL);
+		local_irq_disable();
+	}
+	local_irq_enable();
+}
+EXPORT_SYMBOL_GPL(tracehook_handle_notify_resume);
+#endif



  reply index

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 ` Thomas Gleixner [this message]
2019-08-01 14:48   ` [patch 1/5] tracehook: Provide TIF_NOTIFY_RESUME handling for KVM Peter Zijlstra
2019-08-01 15:10     ` Thomas Gleixner
2019-08-01 17:02     ` Andy Lutomirski
2019-08-01 14:32 ` [patch 2/5] x86/kvm: Handle task_work on VMENTER/EXIT Thomas Gleixner
2019-08-01 16:24   ` 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

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20190801143657.785902257@linutronix.de \
    --to=tglx@linutronix.de \
    --cc=anna-maria@linutronix.de \
    --cc=bigeasy@linutronix.de \
    --cc=fweisbec@gmail.com \
    --cc=john.stultz@linaro.org \
    --cc=julia@ni.com \
    --cc=kvm@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=luto@kernel.org \
    --cc=mingo@kernel.org \
    --cc=oleg@redhat.com \
    --cc=paulmck@linux.ibm.com \
    --cc=paulmck@linux.vnet.ibm.com \
    --cc=pbonzini@redhat.com \
    --cc=peterz@infradead.org \
    --cc=rkrcmar@redhat.com \
    --cc=rostedt@goodmis.org \
    --cc=x86@kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

KVM Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/kvm/0 kvm/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 kvm kvm/ https://lore.kernel.org/kvm \
		kvm@vger.kernel.org
	public-inbox-index kvm

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.kvm


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git