From 439a5ef2cfd08ce45e8aab1bd8381fe1c7c184e5 Mon Sep 17 00:00:00 2001 From: Juergen Gross Date: Thu, 13 Mar 2025 13:21:44 +0900 Subject: [PATCH] x86: make get_cpu_vendor() accessible from Xen code BugLink: https://bugs.launchpad.net/bugs/2102181 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 Signed-off-by: Juergen Gross Signed-off-by: Greg Kroah-Hartman Signed-off-by: Koichiro Den Signed-off-by: Mehmet Basaran --- arch/x86/include/asm/processor.h | 2 ++ arch/x86/kernel/cpu/common.c | 38 ++++++++++++++++++-------------- 2 files changed, 24 insertions(+), 16 deletions(-) diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h index 297391414418..f17993ace111 100644 --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -219,6 +219,8 @@ 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_secondary_cpu(struct cpuinfo_x86 *); extern void print_cpu_info(struct cpuinfo_x86 *); diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index f816f44f2a63..804693483472 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -909,7 +909,7 @@ 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; @@ -1682,15 +1682,11 @@ 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; @@ -1698,20 +1694,30 @@ void __init early_cpu_init(void) break; cpu_devs[count] = cpudev; count++; + } +} + +void __init early_cpu_init(void) +{ +#ifdef CONFIG_PROCESSOR_SELECT + unsigned int i, j; + + pr_info("KERNEL supported cpus:\n"); +#endif + + init_cpu_devs(); #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]); - } + 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 } +#endif + early_identify_cpu(&boot_cpu_data); }