KVM: PPC: Book3S: Controls for in-kernel sPAPR hypercall handling
This provides a way for userspace controls which sPAPR hcalls get
handled in the kernel. Each hcall can be individually enabled or
disabled for in-kernel handling, except for H_RTAS. The exception
for H_RTAS is because userspace can already control whether
individual RTAS functions are handled in-kernel or not via the
KVM_PPC_RTAS_DEFINE_TOKEN ioctl, and because the numeric value for
H_RTAS is out of the normal sequence of hcall numbers.
Hcalls are enabled or disabled using the KVM_ENABLE_CAP ioctl for the
KVM_CAP_PPC_ENABLE_HCALL capability on the file descriptor for the VM.
The args field of the struct kvm_enable_cap specifies the hcall number
in args[0] and the enable/disable flag in args[1]; 0 means disable
in-kernel handling (so that the hcall will always cause an exit to
userspace) and 1 means enable. Enabling or disabling in-kernel
handling of an hcall is effective across the whole VM.
The ability for KVM_ENABLE_CAP to be used on a VM file descriptor
on PowerPC is new, added by this commit. The KVM_CAP_ENABLE_CAP_VM
capability advertises that this ability exists.
When a VM is created, an initial set of hcalls are enabled for
in-kernel handling. The set that is enabled is the set that have
an in-kernel implementation at this point. Any new hcall
implementations from this point onwards should not be added to the
default set without a good reason.
No distinction is made between real-mode and virtual-mode hcall
implementations; the one setting controls them both.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Alexander Graf <agraf@suse.de>
diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
index 61c738a..3222a4d 100644
--- a/arch/powerpc/kvm/powerpc.c
+++ b/arch/powerpc/kvm/powerpc.c
@@ -387,6 +387,7 @@
case KVM_CAP_PPC_UNSET_IRQ:
case KVM_CAP_PPC_IRQ_LEVEL:
case KVM_CAP_ENABLE_CAP:
+ case KVM_CAP_ENABLE_CAP_VM:
case KVM_CAP_ONE_REG:
case KVM_CAP_IOEVENTFD:
case KVM_CAP_DEVICE_CTRL:
@@ -417,6 +418,7 @@
case KVM_CAP_PPC_ALLOC_HTAB:
case KVM_CAP_PPC_RTAS:
case KVM_CAP_PPC_FIXUP_HCALL:
+ case KVM_CAP_PPC_ENABLE_HCALL:
#ifdef CONFIG_KVM_XICS
case KVM_CAP_IRQ_XICS:
#endif
@@ -1099,6 +1101,40 @@
return 0;
}
+
+static int kvm_vm_ioctl_enable_cap(struct kvm *kvm,
+ struct kvm_enable_cap *cap)
+{
+ int r;
+
+ if (cap->flags)
+ return -EINVAL;
+
+ switch (cap->cap) {
+#ifdef CONFIG_KVM_BOOK3S_64_HANDLER
+ case KVM_CAP_PPC_ENABLE_HCALL: {
+ unsigned long hcall = cap->args[0];
+
+ r = -EINVAL;
+ if (hcall > MAX_HCALL_OPCODE || (hcall & 3) ||
+ cap->args[1] > 1)
+ break;
+ if (cap->args[1])
+ set_bit(hcall / 4, kvm->arch.enabled_hcalls);
+ else
+ clear_bit(hcall / 4, kvm->arch.enabled_hcalls);
+ r = 0;
+ break;
+ }
+#endif
+ default:
+ r = -EINVAL;
+ break;
+ }
+
+ return r;
+}
+
long kvm_arch_vm_ioctl(struct file *filp,
unsigned int ioctl, unsigned long arg)
{
@@ -1118,6 +1154,15 @@
break;
}
+ case KVM_ENABLE_CAP:
+ {
+ struct kvm_enable_cap cap;
+ r = -EFAULT;
+ if (copy_from_user(&cap, argp, sizeof(cap)))
+ goto out;
+ r = kvm_vm_ioctl_enable_cap(kvm, &cap);
+ break;
+ }
#ifdef CONFIG_PPC_BOOK3S_64
case KVM_CREATE_SPAPR_TCE: {
struct kvm_create_spapr_tce create_tce;