Commit efbcd61d authored by Juergen Gross's avatar Juergen Gross
Browse files

x86: make get_cpu_vendor() accessible from Xen code 



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: default avatarAndrew Cooper <andrew.cooper3@citrix.com>
Signed-off-by: default avatarJuergen Gross <jgross@suse.com>
parent f9244fb5

arch/x86/include/asm/processor.h

+2 −0
Original line number Diff line number Diff line
@@ -230,6 +230,8 @@ 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 *);

arch/x86/kernel/cpu/common.c

+22 −16
Original line number Diff line number Diff line
@@ -867,7 +867,7 @@ static void cpu_detect_tlb(struct cpuinfo_x86 *c) 
		tlb_lld_4m[ENTRIES], tlb_lld_1g[ENTRIES]);

}



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;
@@ -1649,15 +1649,11 @@ 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;
@@ -1665,20 +1661,30 @@ void __init early_cpu_init(void) 
			break;

		cpu_devs[count] = cpudev;

		count++;

	}

}



#ifdef CONFIG_PROCESSOR_SELECT

void __init early_cpu_init(void)

{

			unsigned int j;

#ifdef CONFIG_PROCESSOR_SELECT

	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 (!cpudev->c_ident[j])

			if (!cpu_devs[i]->c_ident[j])

				continue;

				pr_info("  %s %s\n", cpudev->c_vendor,

					cpudev->c_ident[j]);

			pr_info("  %s %s\n", cpu_devs[i]->c_vendor,

				cpu_devs[i]->c_ident[j]);

		}

	}

#endif

	}



	early_identify_cpu(&boot_cpu_data);

}