From 7c68af6e32c73992bad24107311f3433c89016e2 Mon Sep 17 00:00:00 2001 From: Avi Kivity Date: Sat, 19 Sep 2009 09:40:22 +0300 Subject: core, x86: Add user return notifiers Add a general per-cpu notifier that is called whenever the kernel is about to return to userspace. The notifier uses a thread_info flag and existing checks, so there is no impact on user return or context switch fast paths. This will be used initially to speed up KVM task switching by lazily updating MSRs. Signed-off-by: Avi Kivity LKML-Reference: <1253342422-13811-1-git-send-email-avi@redhat.com> Signed-off-by: H. Peter Anvin --- arch/Kconfig | 10 ++++++++++ 1 file changed, 10 insertions(+) (limited to 'arch/Kconfig') diff --git a/arch/Kconfig b/arch/Kconfig index 7f418bbc261a..4e312fffbfd7 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -83,6 +83,13 @@ config KRETPROBES def_bool y depends on KPROBES && HAVE_KRETPROBES +config USER_RETURN_NOTIFIER + bool + depends on HAVE_USER_RETURN_NOTIFIER + help + Provide a kernel-internal notification when a cpu is about to + switch to user mode. + config HAVE_IOREMAP_PROT bool @@ -126,4 +133,7 @@ config HAVE_DMA_API_DEBUG config HAVE_DEFAULT_NO_SPIN_MUTEXES bool +config HAVE_USER_RETURN_NOTIFIER + bool + source "kernel/gcov/Kconfig" -- cgit v1.2.3-55-g7522