Commit 5214a9f6 authored by Borislav Petkov (AMD)'s avatar Borislav Petkov (AMD)
Browse files

x86/microcode: Consolidate the loader enablement checking 



Consolidate the whole logic which determines whether the microcode loader
should be enabled or not into a single function and call it everywhere.

Well, almost everywhere - not in mk_early_pgtbl_32() because there the kernel
is running without paging enabled and checking dis_ucode_ldr et al would
require physical addresses and uglification of the code.

But since this is 32-bit, the easier thing to do is to simply map the initrd
unconditionally especially since that mapping is getting removed later anyway
by zap_early_initrd_mapping() and avoid the uglification.

In doing so, address the issue of old 486er machines without CPUID
support, not booting current kernels.

  [ mingo: Fix no previous prototype for ‘microcode_loader_disabled’ [-Wmissing-prototypes] ]

Fixes: 4c585af7 ("x86/boot/32: Temporarily map initrd for microcode loading")
Signed-off-by: default avatarBorislav Petkov (AMD) <bp@alien8.de>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Signed-off-by: default avatarBorislav Petkov (AMD) <bp@alien8.de>
Cc: <stable@kernel.org>
Link: https://lore.kernel.org/r/CANpbe9Wm3z8fy9HbgS8cuhoj0TREYEEkBipDuhgkWFvqX0UoVQ@mail.gmail.com
parent 92a09c47

arch/x86/include/asm/microcode.h

+2 −0
Original line number Diff line number Diff line
@@ -17,10 +17,12 @@ struct ucode_cpu_info { 
void load_ucode_bsp(void);

void load_ucode_ap(void);

void microcode_bsp_resume(void);

bool __init microcode_loader_disabled(void);

#else

static inline void load_ucode_bsp(void)	{ }

static inline void load_ucode_ap(void) { }

static inline void microcode_bsp_resume(void) { }

static inline bool __init microcode_loader_disabled(void) { return false; }

#endif



extern unsigned long initrd_start_early;

arch/x86/kernel/cpu/microcode/amd.c

+4 −2
Original line number Diff line number Diff line
@@ -1098,15 +1098,17 @@ static enum ucode_state load_microcode_amd(u8 family, const u8 *data, size_t siz 


static int __init save_microcode_in_initrd(void)

{

	unsigned int cpuid_1_eax = native_cpuid_eax(1);

	struct cpuinfo_x86 *c = &boot_cpu_data;

	struct cont_desc desc = { 0 };

	unsigned int cpuid_1_eax;

	enum ucode_state ret;

	struct cpio_data cp;



	if (dis_ucode_ldr || c->x86_vendor != X86_VENDOR_AMD || c->x86 < 0x10)

	if (microcode_loader_disabled() || c->x86_vendor != X86_VENDOR_AMD || c->x86 < 0x10)

		return 0;



	cpuid_1_eax = native_cpuid_eax(1);



	if (!find_blobs_in_containers(&cp))

		return -EINVAL;

arch/x86/kernel/cpu/microcode/core.c

+34 −24
Original line number Diff line number Diff line
@@ -42,7 +42,7 @@ 
#include "internal.h"



static struct microcode_ops *microcode_ops;

bool dis_ucode_ldr = true;

static bool dis_ucode_ldr = false;



bool force_minrev = IS_ENABLED(CONFIG_MICROCODE_LATE_FORCE_MINREV);

module_param(force_minrev, bool, S_IRUSR | S_IWUSR);
@@ -84,6 +84,9 @@ static bool amd_check_current_patch_level(void) 
	u32 lvl, dummy, i;

	u32 *levels;



	if (x86_cpuid_vendor() != X86_VENDOR_AMD)

		return false;



	native_rdmsr(MSR_AMD64_PATCH_LEVEL, lvl, dummy);



	levels = final_levels;
@@ -95,27 +98,29 @@ static bool amd_check_current_patch_level(void) 
	return false;

}



static bool __init check_loader_disabled_bsp(void)

bool __init microcode_loader_disabled(void)

{

	static const char *__dis_opt_str = "dis_ucode_ldr";

	const char *cmdline = boot_command_line;

	const char *option  = __dis_opt_str;

	if (dis_ucode_ldr)

		return true;



	/*

	 * CPUID(1).ECX[31]: reserved for hypervisor use. This is still not

	 * completely accurate as xen pv guests don't see that CPUID bit set but

	 * that's good enough as they don't land on the BSP path anyway.

	 * Disable when:

	 *

	 * 1) The CPU does not support CPUID.

	 *

	 * 2) Bit 31 in CPUID[1]:ECX is clear

	 *    The bit is reserved for hypervisor use. This is still not

	 *    completely accurate as XEN PV guests don't see that CPUID bit

	 *    set, but that's good enough as they don't land on the BSP

	 *    path anyway.

	 *

	 * 3) Certain AMD patch levels are not allowed to be

	 *    overwritten.

	 */

	if (native_cpuid_ecx(1) & BIT(31))

		return true;



	if (x86_cpuid_vendor() == X86_VENDOR_AMD) {

		if (amd_check_current_patch_level())

			return true;

	}



	if (cmdline_find_option_bool(cmdline, option) <= 0)

		dis_ucode_ldr = false;

	if (!have_cpuid_p() ||

	    native_cpuid_ecx(1) & BIT(31) ||

	    amd_check_current_patch_level())

		dis_ucode_ldr = true;



	return dis_ucode_ldr;

}
@@ -125,7 +130,10 @@ void __init load_ucode_bsp(void) 
	unsigned int cpuid_1_eax;

	bool intel = true;



	if (!have_cpuid_p())

	if (cmdline_find_option_bool(boot_command_line, "dis_ucode_ldr") > 0)

		dis_ucode_ldr = true;



	if (microcode_loader_disabled())

		return;



	cpuid_1_eax = native_cpuid_eax(1);
@@ -146,9 +154,6 @@ void __init load_ucode_bsp(void) 
		return;

	}



	if (check_loader_disabled_bsp())

		return;



	if (intel)

		load_ucode_intel_bsp(&early_data);

	else
@@ -159,6 +164,11 @@ void load_ucode_ap(void) 
{

	unsigned int cpuid_1_eax;



	/*

	 * Can't use microcode_loader_disabled() here - .init section

	 * hell. It doesn't have to either - the BSP variant must've

	 * parsed cmdline already anyway.

	 */

	if (dis_ucode_ldr)

		return;
@@ -810,7 +820,7 @@ static int __init microcode_init(void) 
	struct cpuinfo_x86 *c = &boot_cpu_data;

	int error;



	if (dis_ucode_ldr)

	if (microcode_loader_disabled())

		return -EINVAL;



	if (c->x86_vendor == X86_VENDOR_INTEL)

arch/x86/kernel/cpu/microcode/intel.c

+1 −1
Original line number Diff line number Diff line
@@ -389,7 +389,7 @@ static int __init save_builtin_microcode(void) 
	if (xchg(&ucode_patch_va, NULL) != UCODE_BSP_LOADED)

		return 0;



	if (dis_ucode_ldr || boot_cpu_data.x86_vendor != X86_VENDOR_INTEL)

	if (microcode_loader_disabled() || boot_cpu_data.x86_vendor != X86_VENDOR_INTEL)

		return 0;



	uci.mc = get_microcode_blob(&uci, true);

arch/x86/kernel/cpu/microcode/internal.h

+0 −1
Original line number Diff line number Diff line
@@ -94,7 +94,6 @@ static inline unsigned int x86_cpuid_family(void) 
	return x86_family(eax);

}



extern bool dis_ucode_ldr;

extern bool force_minrev;



#ifdef CONFIG_CPU_SUP_AMD