[Qemu-devel] [PATCH for-2.2] spapr: add host Linux version information to device tree

[cyrilbur@gmail.com]

It may prove useful know which Linux distribution version the host machine
is running when an issue in the guest arises but a user cannot access
the host.

Signed-off-by: Cyril Bur <cyril.bur@au1.ibm.com>
---
 hw/ppc/spapr.c       |  8 +++++++
 target-ppc/kvm.c     | 62 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 target-ppc/kvm_ppc.h |  6 +++++
 3 files changed, 76 insertions(+)

diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index 6b48a26..391d47a 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -375,6 +375,14 @@ static void *spapr_create_fdt_skel(hwaddr initrd_base,
     _FDT((fdt_property_string(fdt, "vm,uuid", buf)));
     g_free(buf);
 
+    /*
+     * Add info to the guest FDT to tell it what linux the host is
+     */
+    if (kvmppc_get_linux_host(&buf)) {
+        _FDT((fdt_property_string(fdt, "linux,host", buf)));
+        g_free(buf);
+    }
+
     _FDT((fdt_property_cell(fdt, "#address-cells", 0x2)));
     _FDT((fdt_property_cell(fdt, "#size-cells", 0x2)));
 
diff --git a/target-ppc/kvm.c b/target-ppc/kvm.c
index 8c9e79c..95e0970 100644
--- a/target-ppc/kvm.c
+++ b/target-ppc/kvm.c
@@ -1415,6 +1415,68 @@ bool kvmppc_get_host_model(char **value)
     return g_file_get_contents("/proc/device-tree/model", value, NULL, NULL);
 }
 
+bool kvmppc_get_linux_host(char **value)
+{
+    FILE *f;
+    int i;
+    char line[512];
+    const char *names[] = {"NAME", "VERSION", "BUILD_ID"};
+    bool names_found[ARRAY_SIZE(names)] = { 0 };
+    GString *output = NULL;
+    f = fopen("/etc/os-release", "r");
+    if (f) {
+        output = g_string_new(NULL);
+        while (fgets(line, sizeof(line), f) && output) {
+            if (!strchr(line, '=')) {
+                continue;
+            }
+
+            for (i = 0; i < ARRAY_SIZE(names); i++) {
+                char *start;
+                int name_len = strlen(names[i]);
+
+                if (strncmp(line, names[i], name_len)) {
+                    continue;
+                }
+                if (names_found[i]) {
+                    break;
+                }
+
+                names_found[i] = true;
+                start = line + name_len + 1;
+                if (*start == '"') {
+                    start++;
+                }
+
+                char *end = start + strlen(start) - 1;
+                while (end >= start && strchr("\"\n\t ", *end)) {
+                    end--;
+                }
+                end[1] = '\0';
+
+                g_string_append(output, start);
+            }
+        }
+        fclose(f);
+    } else {
+        f = fopen("/etc/issue", "r");
+        if (!f) {
+            return false;
+        }
+
+        fgets(line, sizeof(line), f);
+        fclose(f);
+        output = g_string_new(line);
+    }
+
+    if (output) {
+        *value = g_string_free(output, false);
+        return true;
+    }
+
+    return false;
+}
+
 /* Try to find a device tree node for a CPU with clock-frequency property */
 static int kvmppc_find_cpu_dt(char *buf, int buf_len)
 {
diff --git a/target-ppc/kvm_ppc.h b/target-ppc/kvm_ppc.h
index 2e0224c..92a71f7 100644
--- a/target-ppc/kvm_ppc.h
+++ b/target-ppc/kvm_ppc.h
@@ -21,6 +21,7 @@ uint32_t kvmppc_get_vmx(void);
 uint32_t kvmppc_get_dfp(void);
 bool kvmppc_get_host_model(char **buf);
 bool kvmppc_get_host_serial(char **buf);
+bool kvmppc_get_linux_host(char **buf);
 int kvmppc_get_hasidle(CPUPPCState *env);
 int kvmppc_get_hypercall(CPUPPCState *env, uint8_t *buf, int buf_len);
 int kvmppc_set_interrupt(PowerPCCPU *cpu, int irq, int level);
@@ -72,6 +73,11 @@ static inline bool kvmppc_get_host_serial(char **buf)
     return false;
 }
 
+static inline bool kvmppc_get_linux_host(char **buf)
+{
+    return false;
+}
+
 static inline uint64_t kvmppc_get_clockfreq(void)
 {
     return 0;
-- 
1.9.1