KVM: VMX: Add list of potentially locally cached vcpus

VMX hardware can cache the contents of a vcpu's vmcs.  This cache needs
to be flushed when migrating a vcpu to another cpu, or (which is the case
that interests us here) when disabling hardware virtualization on a cpu.

The current implementation of decaching iterates over the list of all vcpus,
picks the ones that are potentially cached on the cpu that is being offlined,
and flushes the cache.  The problem is that it uses mutex_trylock() to gain
exclusive access to the vcpu, which fires off a (benign) warning about using
the mutex in an interrupt context.

To avoid this, and to make things generally nicer, add a new per-cpu list
of potentially cached vcus.  This makes the decaching code much simpler.  The
list is vmx-specific since other hardware doesn't have this issue.

[andrea: fix crash on suspend/resume]

Signed-off-by: Andrea Arcangeli <andrea@qumranet.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>

1 files changed, 0 insertions, 27 deletions

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 59084a3981c0..8c14ddcaba70 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -823,33 +823,6 @@ out:
  */
 void decache_vcpus_on_cpu(int cpu)
 {
-	struct kvm *vm;
-	struct kvm_vcpu *vcpu;
-	int i;
-
-	spin_lock(&kvm_lock);
-	list_for_each_entry(vm, &vm_list, vm_list)
-		for (i = 0; i < KVM_MAX_VCPUS; ++i) {
-			vcpu = vm->vcpus[i];
-			if (!vcpu)
-				continue;
-			/*
-			 * If the vcpu is locked, then it is running on some
-			 * other cpu and therefore it is not cached on the
-			 * cpu in question.
-			 *
-			 * If it's not locked, check the last cpu it executed
-			 * on.
-			 */
-			if (mutex_trylock(&vcpu->mutex)) {
-				if (vcpu->cpu == cpu) {
-					kvm_x86_ops->vcpu_decache(vcpu);
-					vcpu->cpu = -1;
-				}
-				mutex_unlock(&vcpu->mutex);
-			}
-		}
-	spin_unlock(&kvm_lock);
 }
 
 int kvm_dev_ioctl_check_extension(long ext)