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authorChristian Borntraeger <borntraeger@de.ibm.com>2015-04-30 13:43:30 +0200
committerAlex Shi <alex.shi@linaro.org>2016-05-24 11:10:08 +0800
commite0497e5362b9fa13bbd0cdb43ea5d7739a919e22 (patch)
tree07044671ffaf01cc5b3757f950c1e3db9a6cbe0c
parentdc61eb672d45359d3b5547e939e49ea1281d335f (diff)
downloadlinux-linaro-stable-e0497e5362b9fa13bbd0cdb43ea5d7739a919e22.tar.gz
KVM: provide irq_unsafe kvm_guest_{enter|exit}
Several kvm architectures disable interrupts before kvm_guest_enter. kvm_guest_enter then uses local_irq_save/restore to disable interrupts again or for the first time. Lets provide underscore versions of kvm_guest_{enter|exit} that assume being called locked. kvm_guest_enter now disables interrupts for the full function and thus we can remove the check for preemptible. This patch then adopts s390/kvm to use local_irq_disable/enable calls which are slighty cheaper that local_irq_save/restore and call these new functions. Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> (cherry picked from commit 0097d12e504b3ce57b68810737ad6a5a64a98c68) Signed-off-by: Alex Shi <alex.shi@linaro.org>
-rw-r--r--arch/s390/kvm/kvm-s390.c10
-rw-r--r--include/linux/kvm_host.h27
2 files changed, 24 insertions, 13 deletions
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index c3805cf4b982..2e840c64aa5c 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -1999,12 +1999,14 @@ static int __vcpu_run(struct kvm_vcpu *vcpu)
* As PF_VCPU will be used in fault handler, between
* guest_enter and guest_exit should be no uaccess.
*/
- preempt_disable();
- kvm_guest_enter();
- preempt_enable();
+ local_irq_disable();
+ __kvm_guest_enter();
+ local_irq_enable();
exit_reason = sie64a(vcpu->arch.sie_block,
vcpu->run->s.regs.gprs);
- kvm_guest_exit();
+ local_irq_disable();
+ __kvm_guest_exit();
+ local_irq_enable();
vcpu->srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);
rc = vcpu_post_run(vcpu, exit_reason);
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 29a57a5b7cee..110964d19e5a 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -773,16 +773,10 @@ static inline void kvm_iommu_unmap_pages(struct kvm *kvm,
}
#endif
-static inline void kvm_guest_enter(void)
+/* must be called with irqs disabled */
+static inline void __kvm_guest_enter(void)
{
- unsigned long flags;
-
- BUG_ON(preemptible());
-
- local_irq_save(flags);
guest_enter();
- local_irq_restore(flags);
-
/* 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
@@ -794,12 +788,27 @@ static inline void kvm_guest_enter(void)
rcu_virt_note_context_switch(smp_processor_id());
}
+/* must be called with irqs disabled */
+static inline void __kvm_guest_exit(void)
+{
+ guest_exit();
+}
+
+static inline void kvm_guest_enter(void)
+{
+ unsigned long flags;
+
+ local_irq_save(flags);
+ __kvm_guest_enter();
+ local_irq_restore(flags);
+}
+
static inline void kvm_guest_exit(void)
{
unsigned long flags;
local_irq_save(flags);
- guest_exit();
+ __kvm_guest_exit();
local_irq_restore(flags);
}