KVM: Add compat ioctl for KVM_SET_SIGNAL_MASK

KVM has an ioctl to define which signal mask should be used while running
inside VCPU_RUN. At least for big endian systems, this mask is different
on 32-bit and 64-bit systems (though the size is identical).

Add a compat wrapper that converts the mask to whatever the kernel accepts,
allowing 32-bit kvm user space to set signal masks.

This patch fixes qemu with --enable-io-thread on ppc64 hosts when running
32-bit user land.

Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Avi Kivity <avi@redhat.com>

1 files changed, 51 insertions, 1 deletions

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index fa2321ac77cc..11d2783eb9df 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -84,6 +84,10 @@ struct dentry *kvm_debugfs_dir;
 
 static long kvm_vcpu_ioctl(struct file *file, unsigned int ioctl,
                            unsigned long arg);
+#ifdef CONFIG_COMPAT
+static long kvm_vcpu_compat_ioctl(struct file *file, unsigned int ioctl,
+                                  unsigned long arg);
+#endif
 static int hardware_enable_all(void);
 static void hardware_disable_all(void);
 
@@ -1586,7 +1590,9 @@ static int kvm_vcpu_release(struct inode *inode, struct file *filp)
 static struct file_operations kvm_vcpu_fops = {
         .release        = kvm_vcpu_release,
         .unlocked_ioctl = kvm_vcpu_ioctl,
-        .compat_ioctl   = kvm_vcpu_ioctl,
+#ifdef CONFIG_COMPAT
+        .compat_ioctl   = kvm_vcpu_compat_ioctl,
+#endif
         .mmap           = kvm_vcpu_mmap,
         .llseek         = noop_llseek,
 };
@@ -1875,6 +1881,50 @@ out:
         return r;
 }
 
+#ifdef CONFIG_COMPAT
+static long kvm_vcpu_compat_ioctl(struct file *filp,
+                                  unsigned int ioctl, unsigned long arg)
+{
+        struct kvm_vcpu *vcpu = filp->private_data;
+        void __user *argp = compat_ptr(arg);
+        int r;
+
+        if (vcpu->kvm->mm != current->mm)
+                return -EIO;
+
+        switch (ioctl) {
+        case KVM_SET_SIGNAL_MASK: {
+                struct kvm_signal_mask __user *sigmask_arg = argp;
+                struct kvm_signal_mask kvm_sigmask;
+                compat_sigset_t csigset;
+                sigset_t sigset;
+
+                if (argp) {
+                        r = -EFAULT;
+                        if (copy_from_user(&kvm_sigmask, argp,
+                                           sizeof kvm_sigmask))
+                                goto out;
+                        r = -EINVAL;
+                        if (kvm_sigmask.len != sizeof csigset)
+                                goto out;
+                        r = -EFAULT;
+                        if (copy_from_user(&csigset, sigmask_arg->sigset,
+                                           sizeof csigset))
+                                goto out;
+                }
+                sigset_from_compat(&sigset, &csigset);
+                r = kvm_vcpu_ioctl_set_sigmask(vcpu, &sigset);
+                break;
+        }
+        default:
+                r = kvm_vcpu_ioctl(filp, ioctl, arg);
+        }
+
+out:
+        return r;
+}
+#endif
+
 static long kvm_vm_ioctl(struct file *filp,
                            unsigned int ioctl, unsigned long arg)
 {