[PATCH 6.14 128/197] x86/microcode: Consolidate the loader enablement checking

6.14-stable review patch. If anyone has any objections, please let me know.

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From: Borislav Petkov (AMD) bp@alien8.de

commit 5214a9f6c0f56644acb9d2cbb58facf1856d322b upstream.

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: 4c585af7180c1 ("x86/boot/32: Temporarily map initrd for microcode loading") Signed-off-by: Borislav Petkov (AMD) bp@alien8.de Signed-off-by: Ingo Molnar mingo@kernel.org Signed-off-by: Borislav Petkov (AMD) bp@alien8.de Cc: stable@kernel.org Link: https://lore.kernel.org/r/CANpbe9Wm3z8fy9HbgS8cuhoj0TREYEEkBipDuhgkWFvqX0UoV... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/x86/include/asm/microcode.h | 2 + arch/x86/kernel/cpu/microcode/amd.c | 6 ++- arch/x86/kernel/cpu/microcode/core.c | 58 ++++++++++++++++++------------- arch/x86/kernel/cpu/microcode/intel.c | 2 - arch/x86/kernel/cpu/microcode/internal.h | 1 arch/x86/kernel/head32.c | 4 -- 6 files changed, 41 insertions(+), 32 deletions(-)

--- a/arch/x86/include/asm/microcode.h +++ b/arch/x86/include/asm/microcode.h @@ -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; --- a/arch/x86/kernel/cpu/microcode/amd.c +++ b/arch/x86/kernel/cpu/microcode/amd.c @@ -1098,15 +1098,17 @@ static enum ucode_state load_microcode_a

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;

--- a/arch/x86/kernel/cpu/microcode/core.c +++ b/arch/x86/kernel/cpu/microcode/core.c @@ -41,8 +41,8 @@

#include "internal.h"

-static struct microcode_ops *microcode_ops; -bool dis_ucode_ldr = true; +static struct microcode_ops *microcode_ops; +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_leve 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_leve 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) --- a/arch/x86/kernel/cpu/microcode/intel.c +++ b/arch/x86/kernel/cpu/microcode/intel.c @@ -389,7 +389,7 @@ static int __init save_builtin_microcode 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); --- a/arch/x86/kernel/cpu/microcode/internal.h +++ b/arch/x86/kernel/cpu/microcode/internal.h @@ -94,7 +94,6 @@ static inline unsigned int x86_cpuid_fam return x86_family(eax); }

-extern bool dis_ucode_ldr; extern bool force_minrev;

#ifdef CONFIG_CPU_SUP_AMD --- a/arch/x86/kernel/head32.c +++ b/arch/x86/kernel/head32.c @@ -145,10 +145,6 @@ void __init __no_stack_protector mk_earl *ptr = (unsigned long)ptep + PAGE_OFFSET;

#ifdef CONFIG_MICROCODE_INITRD32 - /* Running on a hypervisor? */ - if (native_cpuid_ecx(1) & BIT(31)) - return; - params = (struct boot_params *)__pa_nodebug(&boot_params); if (!params->hdr.ramdisk_size || !params->hdr.ramdisk_image) return;