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| author | Peter Zijlstra <peterz@infradead.org> | 2026-08-04 07:15:41 +0000 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2026-08-07 17:58:09 +0200 |
| commit | fc6ad5eadcd1694d2f1ee2717c8024efd8152e20 (patch) | |
| tree | 7ff7e6782eb3be4ef9488799c8fef40854b29b87 /arch/x86/hyperv | |
| parent | 1c7efabfbaf796f11000a46094a69955a01ec6cc (diff) | |
| download | linux-fc6ad5eadcd1694d2f1ee2717c8024efd8152e20.tar.gz linux-fc6ad5eadcd1694d2f1ee2717c8024efd8152e20.zip | |
x86/paravirt: Use static_call() for the paravirt spinlock ops
queued_spin_lock_slowpath() and queued_spin_unlock() are dispatched
through pv_ops_lock via the paravirt-ops ALTERNATIVE machinery, which
picks the target (native inline store / hypervisor call) once at boot
and cannot change at runtime.
Convert both to static_call(). The site becomes a direct call patched in
place (one byte smaller), and on native the unlock still collapses to
the inline "movb $0, (%rdi)" store, so the fast path is unchanged.
Unlike the ALTERNATIVE mechanism, a static_call() target can also be
updated at runtime via static_call_update(). This is a prerequisite for
the contended_release tracepoint, which has to swap in a traced unlock
while the system is running.
[ ilvokhin: commit message; fix PARAVIRT_SPINLOCKS=n build; teach
__static_call_validate() about the inline unlock insn; make the
slowpath site module-safe: static_call_mod() +
EXPORT_STATIC_CALL_TRAMP(); pass @lock to the callee-save unlock,
fixing a boot hang under CALL_DEPTH_TRACKING. Boot tested native + KVM
PV guest. ]
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Co-developed-by: Dmitry Ilvokhin <d@ilvokhin.com>
Signed-off-by: Dmitry Ilvokhin <d@ilvokhin.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/all/20260603120811.GW3493090@noisy.programming.kicks-ass.net/
Link: https://patch.msgid.link/9a32ae399eb804a02a31af04dcabe7e7ee4f3fdf.1785778551.git.d@ilvokhin.com
Diffstat (limited to 'arch/x86/hyperv')
| -rw-r--r-- | arch/x86/hyperv/hv_spinlock.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/x86/hyperv/hv_spinlock.c b/arch/x86/hyperv/hv_spinlock.c index 210b494e4de0..6b4bdea18218 100644 --- a/arch/x86/hyperv/hv_spinlock.c +++ b/arch/x86/hyperv/hv_spinlock.c @@ -78,8 +78,8 @@ void __init hv_init_spinlocks(void) pr_info("PV spinlocks enabled\n"); __pv_init_lock_hash(); - pv_ops_lock.queued_spin_lock_slowpath = __pv_queued_spin_lock_slowpath; - pv_ops_lock.queued_spin_unlock = PV_CALLEE_SAVE(__pv_queued_spin_unlock); + static_call_update(queued_spin_lock_slowpath, __pv_queued_spin_lock_slowpath); + static_call_update(queued_spin_unlock, __raw_callee_save___pv_queued_spin_unlock); pv_ops_lock.wait = hv_qlock_wait; pv_ops_lock.kick = hv_qlock_kick; pv_ops_lock.vcpu_is_preempted = PV_CALLEE_SAVE(hv_vcpu_is_preempted); |