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[Qemu-devel] [PATCH] spapr: Add support for hwrng when available


From: Michael Ellerman
Subject: [Qemu-devel] [PATCH] spapr: Add support for hwrng when available
Date: Thu, 26 Sep 2013 16:37:24 +1000

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 <address@hidden>
---
 hw/ppc/spapr.c            | 16 ++++++++++++++++
 include/hw/ppc/spapr.h    |  1 +
 linux-headers/linux/kvm.h |  1 +
 target-ppc/kvm.c          |  5 +++++
 target-ppc/kvm_ppc.h      |  5 +++++
 5 files changed, 28 insertions(+)

diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index 004184d..5909df1 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -497,6 +497,22 @@ static void *spapr_create_fdt_skel(const char *cpu_model,
 
     _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 e37b419..c509500 100644
--- a/include/hw/ppc/spapr.h
+++ b/include/hw/ppc/spapr.h
@@ -283,6 +283,7 @@ typedef struct sPAPREnvironment {
 #define H_GET_EM_PARMS          0x2B8
 #define H_SET_MPP               0x2D0
 #define H_GET_MPP               0x2D4
+#define H_RANDOM                0x300
 #define H_SET_MODE              0x31C
 #define MAX_HCALL_OPCODE        H_SET_MODE
 
diff --git a/linux-headers/linux/kvm.h b/linux-headers/linux/kvm.h
index c614070..7be746c 100644
--- a/linux-headers/linux/kvm.h
+++ b/linux-headers/linux/kvm.h
@@ -666,6 +666,7 @@ struct kvm_ppc_smmu_info {
 #define KVM_CAP_IRQ_MPIC 90
 #define KVM_CAP_PPC_RTAS 91
 #define KVM_CAP_IRQ_XICS 92
+#define KVM_CAP_PPC_HWRNG 95
 
 #ifdef KVM_CAP_IRQ_ROUTING
 
diff --git a/target-ppc/kvm.c b/target-ppc/kvm.c
index 8a196c6..faf5dae 100644
--- a/target-ppc/kvm.c
+++ b/target-ppc/kvm.c
@@ -1875,3 +1875,8 @@ int kvm_arch_on_sigbus(int code, void *addr)
 void kvm_arch_init_irq_routing(KVMState *s)
 {
 }
+
+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 4ae7bf2..b7b898b 100644
--- a/target-ppc/kvm_ppc.h
+++ b/target-ppc/kvm_ppc.h
@@ -42,6 +42,7 @@ int kvmppc_get_htab_fd(bool write);
 int kvmppc_save_htab(QEMUFile *f, int fd, size_t bufsize, int64_t max_ns);
 int kvmppc_load_htab_chunk(QEMUFile *f, int fd, uint32_t index,
                            uint16_t n_valid, uint16_t n_invalid);
+bool kvmppc_hwrng_present(void);
 
 #else
 
@@ -181,6 +182,10 @@ static inline int kvmppc_load_htab_chunk(QEMUFile *f, int 
fd, uint32_t index,
     abort();
 }
 
+static inline bool kvmppc_hwrng_present(void)
+{
+    return false;
+}
 #endif
 
 #ifndef CONFIG_KVM
-- 
1.8.1.2




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