[RFC PATCH for-4.22 2/2] tools: Introduce xen-inteltemp tool

["Teddy Astie" <teddy.astie@xxxxxxxxxx>]

Introduce a new tool to fetch Intel CPU temperatures through the
Intel DTS interface using XENPF_resource_op hypercall.

Signed-off-by: Teddy Astie <teddy.astie@xxxxxxxxxx>
---
 tools/misc/.gitignore      |  1 +
 tools/misc/Makefile        |  4 ++
 tools/misc/xen-inteltemp.c | 98 ++++++++++++++++++++++++++++++++++++++
 3 files changed, 103 insertions(+)
 create mode 100644 tools/misc/xen-inteltemp.c

diff --git a/tools/misc/.gitignore b/tools/misc/.gitignore
index 28af46280f..65048eb901 100644
--- a/tools/misc/.gitignore
+++ b/tools/misc/.gitignore
@@ -5,6 +5,7 @@ xen-diag
 xen-hptool
 xen-hvmcrash
 xen-hvmctx
+xen-inteltemp
 xen-livepatch
 xen-lowmemd
 xen-mceinj
diff --git a/tools/misc/Makefile b/tools/misc/Makefile
index c26e544e83..6498b47ec0 100644
--- a/tools/misc/Makefile
+++ b/tools/misc/Makefile
@@ -25,6 +25,7 @@ INSTALL_SBIN-$(CONFIG_X86)     += xen-memshare
 INSTALL_SBIN-$(CONFIG_X86)     += xen-mfndump
 INSTALL_SBIN-$(CONFIG_X86)     += xen-ucode
 INSTALL_SBIN-$(CONFIG_X86)     += xen-vmtrace
+INSTALL_SBIN-$(CONFIG_X86)     += xen-inteltemp
 INSTALL_SBIN                   += xencov
 INSTALL_SBIN                   += xenhypfs
 INSTALL_SBIN                   += xenlockprof
@@ -89,6 +90,9 @@ xen-memshare: xen-memshare.o
 xen-vmtrace: xen-vmtrace.o
        $(CC) $(LDFLAGS) -o $@ $< $(LDLIBS_libxenctrl) 
$(LDLIBS_libxenforeignmemory) $(APPEND_LDFLAGS)

+xen-inteltemp: xen-inteltemp.o
+       $(CC) $(LDFLAGS) -o $@ $< $(LDLIBS_libxenctrl) $(APPEND_LDFLAGS)
+
 xen-mceinj: xen-mceinj.o
        $(CC) $(LDFLAGS) -o $@ $< $(LDLIBS_libxenctrl) $(LDLIBS_libxenguest) 
$(LDLIBS_libxenstore) $(APPEND_LDFLAGS)

diff --git a/tools/misc/xen-inteltemp.c b/tools/misc/xen-inteltemp.c
new file mode 100644
index 0000000000..624c74ca7f
--- /dev/null
+++ b/tools/misc/xen-inteltemp.c
@@ -0,0 +1,98 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * xen-inteltemp.c
+ *
+ * Get the CPU temperature of Intel processors.
+ *
+ * Copyright 2025 Teddy Astie <teddy.astie@xxxxxxxxxx>
+ */
+
+#include <stdio.h>
+#include <errno.h>
+#include <xenctrl.h>
+
+#define MSR_IA32_THERM_STATUS         0x0000019c
+#define MSR_IA32_TEMPERATURE_TARGET   0x000001a2
+#define MSR_IA32_PACKAGE_THERM_STATUS 0x000001b1
+
+int fetch_dts_temp(xc_interface *xch, uint32_t cpu, bool package, int *temp)
+{
+    xc_resource_entry_t entries[2] = {
+        (xc_resource_entry_t){
+            .idx = package ? MSR_IA32_PACKAGE_THERM_STATUS : 
MSR_IA32_THERM_STATUS
+        },
+        (xc_resource_entry_t){ .idx = MSR_IA32_TEMPERATURE_TARGET },
+    };
+    struct xc_resource_op ops = {
+        .cpu = cpu,
+        .entries = entries,
+        .nr_entries = 2,
+    };
+    int tjmax;
+
+    int ret = xc_resource_op(xch, 1, &ops);
+
+    if ( ret <= 0 )
+        /* This CPU isn't online or can't query this MSR */
+        return ret ?: -EOPNOTSUPP;
+
+    if ( ret == 2 )
+        tjmax = (entries[1].val >> 16) & 0xff;
+    else
+    {
+        /*
+         * The CPU doesn't support MSR_IA32_TEMPERATURE_TARGET, we assume it's 
100 which
+         * is correct aside a few selected Atom CPUs. Check coretemp source 
code for more
+         * information.
+         */
+        fprintf(stderr, "CPU%d doesn't support MSR_IA32_TEMPERATURE_TARGET, 
assume "
+               "tjmax=100°C, readings may be incorrect\n", cpu);
+        tjmax = 100;
+    }
+
+    *temp = tjmax - ((entries[0].val >> 16) & 0xff);
+    return 0;
+}
+
+int main(void)
+{
+    int rc = 0, temp, cpu, socket;
+    bool has_data = false;
+    xc_interface *xch = xc_interface_open(0, 0, 0);
+    xc_physinfo_t info;
+
+    if ( (rc = xc_physinfo(xch, &info)) < 0 )
+    {
+        perror("Getting physinfo failed");
+        return rc;
+    }
+
+    /* Per socket measurement */
+    for ( socket = 0, cpu = 0;
+          cpu < (info.max_cpu_id + 1);
+          socket++, cpu += info.cores_per_socket * info.threads_per_core )
+    {
+        if ( !fetch_dts_temp(xch, cpu, true, &temp) )
+        {
+            has_data = true;
+            printf("Package%d: %d°C\n", socket, temp);
+        }
+    }
+
+    printf("\n");
+
+    for ( cpu = 0; cpu < (info.max_cpu_id + 1); cpu += info.threads_per_core )
+    {
+        if ( fetch_dts_temp(xch, cpu, false, &temp) )
+            continue;
+
+        has_data = true;
+        printf("CPU%d: %d°C\n", cpu, temp);
+    }
+
+    if ( !has_data )
+        printf("No data\n");
+
+    xc_interface_close(xch);
+    return 0;
+}
\ No newline at end of file
--
2.51.1



--
Teddy Astie | Vates XCP-ng Developer

XCP-ng & Xen Orchestra - Vates solutions

web: https://vates.tech