KVM: Move vcpu_load to arch-specific kvm_arch_vcpu_ioctl

Move the calls to vcpu_load() and vcpu_put() in to the architecture
specific implementations of kvm_arch_vcpu_ioctl() which dispatches
further architecture-specific ioctls on to other functions.

Some architectures support asynchronous vcpu ioctls which cannot call
vcpu_load() or take the vcpu->mutex, because that would prevent
concurrent execution with a running VCPU, which is the intended purpose
of these ioctls, for example because they inject interrupts.

We repeat the separate checks for these specifics in the architecture
code for MIPS, S390 and PPC, and avoid taking the vcpu->mutex and
calling vcpu_load for these ioctls.

Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 7 insertions, 6 deletions

diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
index 4e2167a7ae19..ba8134a989c1 100644
--- a/arch/powerpc/kvm/powerpc.c
+++ b/arch/powerpc/kvm/powerpc.c
@@ -1614,16 +1614,16 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
 	void __user *argp = (void __user *)arg;
 	long r;
 
-	switch (ioctl) {
-	case KVM_INTERRUPT: {
+	if (ioctl == KVM_INTERRUPT) {
 		struct kvm_interrupt irq;
-		r = -EFAULT;
 		if (copy_from_user(&irq, argp, sizeof(irq)))
-			goto out;
-		r = kvm_vcpu_ioctl_interrupt(vcpu, &irq);
-		goto out;
+			return -EFAULT;
+		return kvm_vcpu_ioctl_interrupt(vcpu, &irq);
 	}
 
+	vcpu_load(vcpu);
+
+	switch (ioctl) {
 	case KVM_ENABLE_CAP:
 	{
 		struct kvm_enable_cap cap;
@@ -1663,6 +1663,7 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
 	}
 
 out:
+	vcpu_put(vcpu);
 	return r;
 }