[tip: x86/urgent] context_tracking: Consolidate guest enter/exit wrappers

From: tip-bot2 for Sean Christopherson
Date: Thu May 06 2021 - 08:14:18 EST


The following commit has been merged into the x86/urgent branch of tip:

Commit-ID: 14296e0c447885d6c7b326e059fb528eb00526ed
Gitweb: https://git.kernel.org/tip/14296e0c447885d6c7b326e059fb528eb00526ed
Author: Sean Christopherson <seanjc@xxxxxxxxxx>
AuthorDate: Tue, 04 May 2021 17:27:33 -07:00
Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitterDate: Wed, 05 May 2021 22:54:11 +02:00

context_tracking: Consolidate guest enter/exit wrappers

Consolidate the guest enter/exit wrappers, providing and tweaking stubs
as needed. This will allow moving the wrappers under KVM without having
to bleed #ifdefs into the soon-to-be KVM code.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20210505002735.1684165-7-seanjc@xxxxxxxxxx

---
include/linux/context_tracking.h | 65 +++++++++++--------------------
1 file changed, 24 insertions(+), 41 deletions(-)

diff --git a/include/linux/context_tracking.h b/include/linux/context_tracking.h
index 56c648b..aa58c2a 100644
--- a/include/linux/context_tracking.h
+++ b/include/linux/context_tracking.h
@@ -71,6 +71,19 @@ static inline void exception_exit(enum ctx_state prev_ctx)
}
}

+static __always_inline bool context_tracking_guest_enter(void)
+{
+ if (context_tracking_enabled())
+ __context_tracking_enter(CONTEXT_GUEST);
+
+ return context_tracking_enabled_this_cpu();
+}
+
+static __always_inline void context_tracking_guest_exit(void)
+{
+ if (context_tracking_enabled())
+ __context_tracking_exit(CONTEXT_GUEST);
+}

/**
* ct_state() - return the current context tracking state if known
@@ -92,6 +105,9 @@ static inline void user_exit_irqoff(void) { }
static inline enum ctx_state exception_enter(void) { return 0; }
static inline void exception_exit(enum ctx_state prev_ctx) { }
static inline enum ctx_state ct_state(void) { return CONTEXT_DISABLED; }
+static inline bool context_tracking_guest_enter(void) { return false; }
+static inline void context_tracking_guest_exit(void) { }
+
#endif /* !CONFIG_CONTEXT_TRACKING */

#define CT_WARN_ON(cond) WARN_ON(context_tracking_enabled() && (cond))
@@ -102,74 +118,41 @@ extern void context_tracking_init(void);
static inline void context_tracking_init(void) { }
#endif /* CONFIG_CONTEXT_TRACKING_FORCE */

-
-#ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
/* must be called with irqs disabled */
static __always_inline void guest_enter_irqoff(void)
{
+ /*
+ * This is running in ioctl context so its safe to assume that it's the
+ * stime pending cputime to flush.
+ */
instrumentation_begin();
- if (vtime_accounting_enabled_this_cpu())
- vtime_guest_enter(current);
- else
- current->flags |= PF_VCPU;
+ vtime_account_guest_enter();
instrumentation_end();

- if (context_tracking_enabled())
- __context_tracking_enter(CONTEXT_GUEST);
-
- /* KVM does not hold any references to rcu protected data when it
+ /*
+ * KVM does not hold any references to rcu protected data when it
* switches CPU into a guest mode. In fact switching to a guest mode
* is very similar to exiting to userspace from rcu point of view. In
* addition CPU may stay in a guest mode for quite a long time (up to
* one time slice). Lets treat guest mode as quiescent state, just like
* we do with user-mode execution.
*/
- if (!context_tracking_enabled_this_cpu()) {
+ if (!context_tracking_guest_enter()) {
instrumentation_begin();
rcu_virt_note_context_switch(smp_processor_id());
instrumentation_end();
}
}

-static __always_inline void context_tracking_guest_exit(void)
-{
- if (context_tracking_enabled())
- __context_tracking_exit(CONTEXT_GUEST);
-}
-
static __always_inline void guest_exit_irqoff(void)
{
context_tracking_guest_exit();

instrumentation_begin();
- vtime_account_guest_exit();
- instrumentation_end();
-}
-
-#else
-static __always_inline void guest_enter_irqoff(void)
-{
- /*
- * This is running in ioctl context so its safe
- * to assume that it's the stime pending cputime
- * to flush.
- */
- instrumentation_begin();
- vtime_account_guest_enter();
- rcu_virt_note_context_switch(smp_processor_id());
- instrumentation_end();
-}
-
-static __always_inline void context_tracking_guest_exit(void) { }
-
-static __always_inline void guest_exit_irqoff(void)
-{
- instrumentation_begin();
/* Flush the guest cputime we spent on the guest */
vtime_account_guest_exit();
instrumentation_end();
}
-#endif /* CONFIG_VIRT_CPU_ACCOUNTING_GEN */

static inline void guest_exit(void)
{