[PATCH v7 06/11] x86, paravirt: Add interface to support kvm/xen vcpu preempted check
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STALE3633d
REVIEWED: 1 (1M)
From: Pan Xinhui <hidden>
Date: 2016-11-02 05:14:04
Also in:
kvm, linux-s390, lkml, virtualization
Subsystem:
locking primitives, paravirt_ops interface, the rest, x86 architecture (32-bit and 64-bit) · Maintainers:
Peter Zijlstra, Ingo Molnar, Will Deacon, Boqun Feng, Juergen Gross, Linus Torvalds, Thomas Gleixner, Borislav Petkov, Dave Hansen
Status: Reviewed.
Revision v7 (3 revisions archived); 1 review trailer.
Revisions (3)
- v5 re-posted go to this post
- v6 [diff against previous] re-posted go to this post re-posted go to this post
- v7 current [diff against previous] re-posted go to this post
This is to fix some lock holder preemption issues. Some other locks implementation do a spin loop before acquiring the lock itself. Currently kernel has an interface of bool vcpu_is_preempted(int cpu). It takes the cpu as parameter and return true if the cpu is preempted. Then kernel can break the spin loops upon the retval of vcpu_is_preempted. As kernel has used this interface, So lets support it. To deal with kernel and kvm/xen, add vcpu_is_preempted into struct pv_lock_ops. Then kvm or xen could provide their own implementation to support vcpu_is_preempted. Signed-off-by: Pan Xinhui <redacted> Acked-by: Paolo Bonzini <pbonzini@redhat.com> --- arch/x86/include/asm/paravirt_types.h | 2 ++ arch/x86/include/asm/spinlock.h | 8 ++++++++ arch/x86/kernel/paravirt-spinlocks.c | 6 ++++++ 3 files changed, 16 insertions(+)
diff --git a/arch/x86/include/asm/paravirt_types.h b/arch/x86/include/asm/paravirt_types.h
index 0f400c0..38c3bb7 100644
--- a/arch/x86/include/asm/paravirt_types.h
+++ b/arch/x86/include/asm/paravirt_types.h@@ -310,6 +310,8 @@ struct pv_lock_ops { void (*wait)(u8 *ptr, u8 val); void (*kick)(int cpu); + + bool (*vcpu_is_preempted)(int cpu); }; /* This contains all the paravirt structures: we get a convenient
diff --git a/arch/x86/include/asm/spinlock.h b/arch/x86/include/asm/spinlock.h
index 921bea7..0526f59 100644
--- a/arch/x86/include/asm/spinlock.h
+++ b/arch/x86/include/asm/spinlock.h@@ -26,6 +26,14 @@ extern struct static_key paravirt_ticketlocks_enabled; static __always_inline bool static_key_false(struct static_key *key); +#ifdef CONFIG_PARAVIRT_SPINLOCKS +#define vcpu_is_preempted vcpu_is_preempted +static inline bool vcpu_is_preempted(int cpu) +{ + return pv_lock_ops.vcpu_is_preempted(cpu); +} +#endif + #include <asm/qspinlock.h> /*
diff --git a/arch/x86/kernel/paravirt-spinlocks.c b/arch/x86/kernel/paravirt-spinlocks.c
index 2c55a00..2f204dd 100644
--- a/arch/x86/kernel/paravirt-spinlocks.c
+++ b/arch/x86/kernel/paravirt-spinlocks.c@@ -21,12 +21,18 @@ bool pv_is_native_spin_unlock(void) __raw_callee_save___native_queued_spin_unlock; } +static bool native_vcpu_is_preempted(int cpu) +{ + return 0; +} + struct pv_lock_ops pv_lock_ops = { #ifdef CONFIG_SMP .queued_spin_lock_slowpath = native_queued_spin_lock_slowpath, .queued_spin_unlock = PV_CALLEE_SAVE(__native_queued_spin_unlock), .wait = paravirt_nop, .kick = paravirt_nop, + .vcpu_is_preempted = native_vcpu_is_preempted, #endif /* SMP */ }; EXPORT_SYMBOL(pv_lock_ops);
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2.4.11