x86: make get_cpu_vendor() accessible from Xen code

commit efbcd61d9bebb771c836a3b8bfced8165633db7c upstream.

In order to be able to differentiate between AMD and Intel based
systems for very early hypercalls without having to rely on the Xen
hypercall page, make get_cpu_vendor() non-static.

Refactor early_cpu_init() for the same reason by splitting out the
loop initializing cpu_devs() into an externally callable function.

This is part of XSA-466 / CVE-2024-53241.

Reported-by: Andrew Cooper <andrew.cooper3@citrix.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 5defef9f286e143ca47e3e8ed367e07a7d1d0621..f43c05aa89e12d50d77230890eae977651b12b26 100644 (file)
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -194,6 +194,8 @@ static inline unsigned long long l1tf_pfn_limit(void)
        return BIT_ULL(boot_cpu_data.x86_cache_bits - 1 - PAGE_SHIFT);
 }
 
+void init_cpu_devs(void);
+void get_cpu_vendor(struct cpuinfo_x86 *c);
 extern void early_cpu_init(void);
 extern void identify_boot_cpu(void);
 extern void identify_secondary_cpu(struct cpuinfo_x86 *);

diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 6d86585f6d24ef4fe9ecbfa4873ade4131d2aa8f..840fdffec850b5f3c67e6e5b69a0eb0e1169f2c7 100644 (file)
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -792,7 +792,7 @@ void detect_ht(struct cpuinfo_x86 *c)
 #endif
 }
 
-static void get_cpu_vendor(struct cpuinfo_x86 *c)
+void get_cpu_vendor(struct cpuinfo_x86 *c)
 {
        char *v = c->x86_vendor_id;
        int i;
@@ -1505,15 +1505,11 @@ static void __init early_identify_cpu(struct cpuinfo_x86 *c)
        detect_nopl();
 }
 
-void __init early_cpu_init(void)
+void __init init_cpu_devs(void)
 {
        const struct cpu_dev *const *cdev;
        int count = 0;
 
-#ifdef CONFIG_PROCESSOR_SELECT
-       pr_info("KERNEL supported cpus:\n");
-#endif
-
        for (cdev = __x86_cpu_dev_start; cdev < __x86_cpu_dev_end; cdev++) {
                const struct cpu_dev *cpudev = *cdev;
 
@@ -1521,20 +1517,30 @@ void __init early_cpu_init(void)
                        break;
                cpu_devs[count] = cpudev;
                count++;
+       }
+}
 
+void __init early_cpu_init(void)
+{
 #ifdef CONFIG_PROCESSOR_SELECT
-               {
-                       unsigned int j;
-
-                       for (j = 0; j < 2; j++) {
-                               if (!cpudev->c_ident[j])
-                                       continue;
-                               pr_info("  %s %s\n", cpudev->c_vendor,
-                                       cpudev->c_ident[j]);
-                       }
-               }
+       unsigned int i, j;
+
+       pr_info("KERNEL supported cpus:\n");
 #endif
+
+       init_cpu_devs();
+
+#ifdef CONFIG_PROCESSOR_SELECT
+       for (i = 0; i < X86_VENDOR_NUM && cpu_devs[i]; i++) {
+               for (j = 0; j < 2; j++) {
+                       if (!cpu_devs[i]->c_ident[j])
+                               continue;
+                       pr_info("  %s %s\n", cpu_devs[i]->c_vendor,
+                               cpu_devs[i]->c_ident[j]);
+               }
        }
+#endif
+
        early_identify_cpu(&boot_cpu_data);
 }