diff options
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.txt | 3 | ||||
| -rw-r--r-- | arch/x86/boot/compressed/cmdline.c | 2 | ||||
| -rw-r--r-- | arch/x86/boot/compressed/head_64.S | 1 | ||||
| -rw-r--r-- | arch/x86/boot/compressed/pgtable_64.c | 12 | ||||
| -rw-r--r-- | arch/x86/kernel/cpu/common.c | 15 | ||||
| -rw-r--r-- | arch/x86/kernel/head64.c | 9 |
6 files changed, 35 insertions, 7 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 11fc28ecdb6d..364a33c1534d 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -2600,6 +2600,9 @@ emulation library even if a 387 maths coprocessor is present. + no5lvl [X86-64] Disable 5-level paging mode. Forces + kernel to use 4-level paging instead. + no_console_suspend [HW] Never suspend the console Disable suspending of consoles during suspend and diff --git a/arch/x86/boot/compressed/cmdline.c b/arch/x86/boot/compressed/cmdline.c index 0cb325734cfb..af6cda0b7900 100644 --- a/arch/x86/boot/compressed/cmdline.c +++ b/arch/x86/boot/compressed/cmdline.c @@ -1,7 +1,7 @@ // SPDX-License-Identifier: GPL-2.0 #include "misc.h" -#if CONFIG_EARLY_PRINTK || CONFIG_RANDOMIZE_BASE +#if CONFIG_EARLY_PRINTK || CONFIG_RANDOMIZE_BASE || CONFIG_X86_5LEVEL static unsigned long fs; static inline void set_fs(unsigned long seg) diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S index 8169e8b7a4dc..64037895b085 100644 --- a/arch/x86/boot/compressed/head_64.S +++ b/arch/x86/boot/compressed/head_64.S @@ -365,6 +365,7 @@ ENTRY(startup_64) * this function call. */ pushq %rsi + movq %rsi, %rdi /* real mode address */ call paging_prepare popq %rsi diff --git a/arch/x86/boot/compressed/pgtable_64.c b/arch/x86/boot/compressed/pgtable_64.c index 23707e1da1ff..8c5107545251 100644 --- a/arch/x86/boot/compressed/pgtable_64.c +++ b/arch/x86/boot/compressed/pgtable_64.c @@ -31,16 +31,23 @@ static char trampoline_save[TRAMPOLINE_32BIT_SIZE]; */ unsigned long *trampoline_32bit __section(.data); -struct paging_config paging_prepare(void) +extern struct boot_params *boot_params; +int cmdline_find_option_bool(const char *option); + +struct paging_config paging_prepare(void *rmode) { struct paging_config paging_config = {}; unsigned long bios_start, ebda_start; + /* Initialize boot_params. Required for cmdline_find_option_bool(). */ + boot_params = rmode; + /* * Check if LA57 is desired and supported. * - * There are two parts to the check: + * There are several parts to the check: * - if the kernel supports 5-level paging: CONFIG_X86_5LEVEL=y + * - if user asked to disable 5-level paging: no5lvl in cmdline * - if the machine supports 5-level paging: * + CPUID leaf 7 is supported * + the leaf has the feature bit set @@ -48,6 +55,7 @@ struct paging_config paging_prepare(void) * That's substitute for boot_cpu_has() in early boot code. */ if (IS_ENABLED(CONFIG_X86_5LEVEL) && + !cmdline_find_option_bool("no5lvl") && native_cpuid_eax(0) >= 7 && (native_cpuid_ecx(7) & (1 << (X86_FEATURE_LA57 & 31)))) { paging_config.l5_required = 1; diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index 39ed2e6ff8a0..27f68d14c962 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -1028,6 +1028,21 @@ static void __init early_identify_cpu(struct cpuinfo_x86 *c) */ setup_clear_cpu_cap(X86_FEATURE_PCID); #endif + + /* + * Later in the boot process pgtable_l5_enabled() relies on + * cpu_feature_enabled(X86_FEATURE_LA57). If 5-level paging is not + * enabled by this point we need to clear the feature bit to avoid + * false-positives at the later stage. + * + * pgtable_l5_enabled() can be false here for several reasons: + * - 5-level paging is disabled compile-time; + * - it's 32-bit kernel; + * - machine doesn't support 5-level paging; + * - user specified 'no5lvl' in kernel command line. + */ + if (!pgtable_l5_enabled()) + setup_clear_cpu_cap(X86_FEATURE_LA57); } void __init early_cpu_init(void) diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c index 8d372d1c266d..8047379e575a 100644 --- a/arch/x86/kernel/head64.c +++ b/arch/x86/kernel/head64.c @@ -80,10 +80,11 @@ static unsigned int __head *fixup_int(void *ptr, unsigned long physaddr) static bool __head check_la57_support(unsigned long physaddr) { - if (native_cpuid_eax(0) < 7) - return false; - - if (!(native_cpuid_ecx(7) & (1 << (X86_FEATURE_LA57 & 31)))) + /* + * 5-level paging is detected and enabled at kernel decomression + * stage. Only check if it has been enabled there. + */ + if (!(native_read_cr4() & X86_CR4_LA57)) return false; *fixup_int(&__pgtable_l5_enabled, physaddr) = 1; |