[Qemu-devel] [PATCH v2 1/2] spapr: Add support for hwrng when available

[Thomas Huth <thuth@redhat.com>]

From: Michael Ellerman <michael@ellerman.id.au>

Some powerpc systems have support for a hardware random number generator
(hwrng). If such a hwrng is present the host kernel can provide access
to it via the H_RANDOM hcall.

The kernel advertises the presence of a hwrng with the KVM_CAP_PPC_HWRNG
capability. If this is detected we add the appropriate device tree bits
to advertise the presence of the hwrng to the guest kernel.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
[thuth: Refreshed patch so it applies to QEMU master branch]
Signed-off-by: Thomas Huth <thuth@redhat.com>
---
 hw/ppc/spapr.c         | 16 ++++++++++++++++
 include/hw/ppc/spapr.h |  1 +
 target-ppc/kvm.c       |  5 +++++
 target-ppc/kvm_ppc.h   |  5 +++++
 4 files changed, 27 insertions(+)

diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index bf0c64f..bc3a112 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -466,6 +466,22 @@ static void *spapr_create_fdt_skel(hwaddr initrd_base,
 
     _FDT((fdt_end_node(fdt)));
 
+    if (kvmppc_hwrng_present()) {
+        _FDT(fdt_begin_node(fdt, "ibm,platform-facilities"));
+
+        _FDT(fdt_property_string(fdt, "name", "ibm,platform-facilities"));
+        _FDT(fdt_property_string(fdt, "device_type",
+                                 "ibm,platform-facilities"));
+        _FDT(fdt_property_cell(fdt, "#address-cells", 0x1));
+        _FDT(fdt_property_cell(fdt, "#size-cells", 0x0));
+        _FDT(fdt_begin_node(fdt, "ibm,random-v1"));
+        _FDT(fdt_property_string(fdt, "name", "ibm,random-v1"));
+        _FDT(fdt_property_string(fdt, "compatible", "ibm,random"));
+        _FDT((fdt_end_node(fdt)));
+    }
+
+    _FDT((fdt_end_node(fdt)));
+
     /* event-sources */
     spapr_events_fdt_skel(fdt, epow_irq);
 
diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
index 91a61ab..ab8906f 100644
--- a/include/hw/ppc/spapr.h
+++ b/include/hw/ppc/spapr.h
@@ -331,6 +331,7 @@ struct sPAPRMachineState {
 #define H_SET_MPP               0x2D0
 #define H_GET_MPP               0x2D4
 #define H_XIRR_X                0x2FC
+#define H_RANDOM                0x300
 #define H_SET_MODE              0x31C
 #define MAX_HCALL_OPCODE        H_SET_MODE
 
diff --git a/target-ppc/kvm.c b/target-ppc/kvm.c
index 110436d..7317f8f 100644
--- a/target-ppc/kvm.c
+++ b/target-ppc/kvm.c
@@ -2484,3 +2484,8 @@ int kvm_arch_msi_data_to_gsi(uint32_t data)
 {
     return data & 0xffff;
 }
+
+bool kvmppc_hwrng_present(void)
+{
+    return kvm_enabled() && kvm_check_extension(kvm_state, KVM_CAP_PPC_HWRNG);
+}
diff --git a/target-ppc/kvm_ppc.h b/target-ppc/kvm_ppc.h
index 4d30e27..62ff601 100644
--- a/target-ppc/kvm_ppc.h
+++ b/target-ppc/kvm_ppc.h
@@ -55,6 +55,7 @@ void kvmppc_hash64_free_pteg(uint64_t token);
 void kvmppc_hash64_write_pte(CPUPPCState *env, target_ulong pte_index,
                              target_ulong pte0, target_ulong pte1);
 bool kvmppc_has_cap_fixup_hcalls(void);
+bool kvmppc_hwrng_present(void);
 
 #else
 
@@ -248,6 +249,10 @@ static inline bool kvmppc_has_cap_fixup_hcalls(void)
     abort();
 }
 
+static inline bool kvmppc_hwrng_present(void)
+{
+    return false;
+}
 #endif
 
 #ifndef CONFIG_KVM
-- 
1.8.3.1