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Diffstat (limited to 'virt')
-rw-r--r--virt/kvm/kvm_main.c52
1 files changed, 36 insertions, 16 deletions
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 0d301c95fa1a..370b95ad5f03 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -3272,6 +3272,35 @@ out:
return ret;
}
+/*
+ * Block the vCPU until the vCPU is runnable, an event arrives, or a signal is
+ * pending. This is mostly used when halting a vCPU, but may also be used
+ * directly for other vCPU non-runnable states, e.g. x86's Wait-For-SIPI.
+ */
+bool kvm_vcpu_block(struct kvm_vcpu *vcpu)
+{
+ struct rcuwait *wait = kvm_arch_vcpu_get_wait(vcpu);
+ bool waited = false;
+
+ kvm_arch_vcpu_blocking(vcpu);
+
+ prepare_to_rcuwait(wait);
+ for (;;) {
+ set_current_state(TASK_INTERRUPTIBLE);
+
+ if (kvm_vcpu_check_block(vcpu) < 0)
+ break;
+
+ waited = true;
+ schedule();
+ }
+ finish_rcuwait(wait);
+
+ kvm_arch_vcpu_unblocking(vcpu);
+
+ return waited;
+}
+
static inline void update_halt_poll_stats(struct kvm_vcpu *vcpu, ktime_t start,
ktime_t end, bool success)
{
@@ -3294,9 +3323,14 @@ static inline void update_halt_poll_stats(struct kvm_vcpu *vcpu, ktime_t start,
}
}
+/*
+ * Emulate a vCPU halt condition, e.g. HLT on x86, WFI on arm, etc... If halt
+ * polling is enabled, busy wait for a short time before blocking to avoid the
+ * expensive block+unblock sequence if a wake event arrives soon after the vCPU
+ * is halted.
+ */
void kvm_vcpu_halt(struct kvm_vcpu *vcpu)
{
- struct rcuwait *wait = kvm_arch_vcpu_get_wait(vcpu);
bool halt_poll_allowed = !kvm_arch_no_poll(vcpu);
bool do_halt_poll = halt_poll_allowed && vcpu->halt_poll_ns;
ktime_t start, cur, poll_end;
@@ -3319,21 +3353,7 @@ void kvm_vcpu_halt(struct kvm_vcpu *vcpu)
} while (kvm_vcpu_can_poll(cur, stop));
}
- kvm_arch_vcpu_blocking(vcpu);
-
- prepare_to_rcuwait(wait);
- for (;;) {
- set_current_state(TASK_INTERRUPTIBLE);
-
- if (kvm_vcpu_check_block(vcpu) < 0)
- break;
-
- waited = true;
- schedule();
- }
- finish_rcuwait(wait);
-
- kvm_arch_vcpu_unblocking(vcpu);
+ waited = kvm_vcpu_block(vcpu);
cur = ktime_get();
if (waited) {