KVM: PPC: Add get_pvinfo interface to query hypercall instructions

We need to tell the guest the opcodes that make up a hypercall through
interfaces that are controlled by userspace. So we need to add a call
for userspace to allow it to query those opcodes so it can pass them
on.

This is required because the hypercall opcodes can change based on
the hypervisor conditions. If we're running in hardware accelerated
hypervisor mode, a hypercall looks different from when we're running
without hardware acceleration.

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

1 files changed, 38 insertions, 0 deletions

diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
index fecfe043458d..6a53a3f86dae 100644
--- a/arch/powerpc/kvm/powerpc.c
+++ b/arch/powerpc/kvm/powerpc.c
@@ -191,6 +191,7 @@ int kvm_dev_ioctl_check_extension(long ext)
 	case KVM_CAP_PPC_UNSET_IRQ:
 	case KVM_CAP_ENABLE_CAP:
 	case KVM_CAP_PPC_OSI:
+	case KVM_CAP_PPC_GET_PVINFO:
 		r = 1;
 		break;
 	case KVM_CAP_COALESCED_MMIO:
@@ -578,16 +579,53 @@ out:
 	return r;
 }
 
+static int kvm_vm_ioctl_get_pvinfo(struct kvm_ppc_pvinfo *pvinfo)
+{
+	u32 inst_lis = 0x3c000000;
+	u32 inst_ori = 0x60000000;
+	u32 inst_nop = 0x60000000;
+	u32 inst_sc = 0x44000002;
+	u32 inst_imm_mask = 0xffff;
+
+	/*
+	 * The hypercall to get into KVM from within guest context is as
+	 * follows:
+	 *
+	 *    lis r0, r0, KVM_SC_MAGIC_R0@h
+	 *    ori r0, KVM_SC_MAGIC_R0@l
+	 *    sc
+	 *    nop
+	 */
+	pvinfo->hcall[0] = inst_lis | ((KVM_SC_MAGIC_R0 >> 16) & inst_imm_mask);
+	pvinfo->hcall[1] = inst_ori | (KVM_SC_MAGIC_R0 & inst_imm_mask);
+	pvinfo->hcall[2] = inst_sc;
+	pvinfo->hcall[3] = inst_nop;
+
+	return 0;
+}
+
 long kvm_arch_vm_ioctl(struct file *filp,
                        unsigned int ioctl, unsigned long arg)
 {
+	void __user *argp = (void __user *)arg;
 	long r;
 
 	switch (ioctl) {
+	case KVM_PPC_GET_PVINFO: {
+		struct kvm_ppc_pvinfo pvinfo;
+		r = kvm_vm_ioctl_get_pvinfo(&pvinfo);
+		if (copy_to_user(argp, &pvinfo, sizeof(pvinfo))) {
+			r = -EFAULT;
+			goto out;
+		}
+
+		break;
+	}
 	default:
 		r = -ENOTTY;
 	}
 
+out:
 	return r;
 }