3 files changed, 72 insertions, 0 deletions

diff --git a/Documentation/kvm/api.txt b/Documentation/kvm/api.txt
index 5f5b64982b1a..44d9893f9db1 100644
--- a/Documentation/kvm/api.txt
+++ b/Documentation/kvm/api.txt
@@ -1032,6 +1032,29 @@ are defined as follows:
    eax, ebx, ecx, edx: the values returned by the cpuid instruction for
          this function/index combination
 
+4.46 KVM_PPC_GET_PVINFO
+
+Capability: KVM_CAP_PPC_GET_PVINFO
+Architectures: ppc
+Type: vm ioctl
+Parameters: struct kvm_ppc_pvinfo (out)
+Returns: 0 on success, !0 on error
+
+struct kvm_ppc_pvinfo {
+        __u32 flags;
+        __u32 hcall[4];
+        __u8  pad[108];
+};
+
+This ioctl fetches PV specific information that need to be passed to the guest
+using the device tree or other means from vm context.
+
+For now the only implemented piece of information distributed here is an array
+of 4 instructions that make up a hypercall.
+
+If any additional field gets added to this structure later on, a bit for that
+additional piece of information will be set in the flags bitmap.
+
 5. The kvm_run structure
 
 Application code obtains a pointer to the kvm_run structure by
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;
 }
 
diff --git a/include/linux/kvm.h b/include/linux/kvm.h
index 636fc381c897..37077045970b 100644
--- a/include/linux/kvm.h
+++ b/include/linux/kvm.h
@@ -414,6 +414,14 @@ struct kvm_enable_cap {
         __u8  pad[64];
 };
 
+/* for KVM_PPC_GET_PVINFO */
+struct kvm_ppc_pvinfo {
+        /* out */
+        __u32 flags;
+        __u32 hcall[4];
+        __u8  pad[108];
+};
+
 #define KVMIO 0xAE
 
 /*
@@ -530,6 +538,7 @@ struct kvm_enable_cap {
 #ifdef __KVM_HAVE_XCRS
 #define KVM_CAP_XCRS 56
 #endif
+#define KVM_CAP_PPC_GET_PVINFO 57
 
 #ifdef KVM_CAP_IRQ_ROUTING
 
@@ -664,6 +673,8 @@ struct kvm_clock_data {
 /* Available with KVM_CAP_PIT_STATE2 */
 #define KVM_GET_PIT2              _IOR(KVMIO,  0x9f, struct kvm_pit_state2)
 #define KVM_SET_PIT2              _IOW(KVMIO,  0xa0, struct kvm_pit_state2)
+/* Available with KVM_CAP_PPC_GET_PVINFO */
+#define KVM_PPC_GET_PVINFO        _IOW(KVMIO,  0xa1, struct kvm_ppc_pvinfo)
 
 /*
  * ioctls for vcpu fds