diff options
Diffstat (limited to 'arch/x86/kernel/head64.c')
| -rw-r--r-- | arch/x86/kernel/head64.c | 236 |
1 files changed, 191 insertions, 45 deletions
diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c index 206a4b6144c2..6a3cfaf6b72a 100644 --- a/arch/x86/kernel/head64.c +++ b/arch/x86/kernel/head64.c @@ -19,14 +19,14 @@ #include <linux/start_kernel.h> #include <linux/io.h> #include <linux/memblock.h> -#include <linux/mem_encrypt.h> +#include <linux/cc_platform.h> +#include <linux/pgtable.h> #include <asm/processor.h> #include <asm/proto.h> #include <asm/smp.h> #include <asm/setup.h> #include <asm/desc.h> -#include <asm/pgtable.h> #include <asm/tlbflush.h> #include <asm/sections.h> #include <asm/kdebug.h> @@ -36,6 +36,11 @@ #include <asm/microcode.h> #include <asm/kasan.h> #include <asm/fixmap.h> +#include <asm/realmode.h> +#include <asm/extable.h> +#include <asm/trapnr.h> +#include <asm/sev.h> +#include <asm/tdx.h> /* * Manage page tables very early on. @@ -61,7 +66,25 @@ unsigned long vmemmap_base __ro_after_init = __VMEMMAP_BASE_L4; EXPORT_SYMBOL(vmemmap_base); #endif -#define __head __section(.head.text) +/* + * GDT used on the boot CPU before switching to virtual addresses. + */ +static struct desc_struct startup_gdt[GDT_ENTRIES] = { + [GDT_ENTRY_KERNEL32_CS] = GDT_ENTRY_INIT(0xc09b, 0, 0xfffff), + [GDT_ENTRY_KERNEL_CS] = GDT_ENTRY_INIT(0xa09b, 0, 0xfffff), + [GDT_ENTRY_KERNEL_DS] = GDT_ENTRY_INIT(0xc093, 0, 0xfffff), +}; + +/* + * Address needs to be set at runtime because it references the startup_gdt + * while the kernel still uses a direct mapping. + */ +static struct desc_ptr startup_gdt_descr = { + .size = sizeof(startup_gdt), + .address = 0, +}; + +#define __head __section(".head.text") static void __head *fixup_pointer(void *ptr, unsigned long physaddr) { @@ -82,7 +105,7 @@ static unsigned int __head *fixup_int(void *ptr, unsigned long physaddr) static bool __head check_la57_support(unsigned long physaddr) { /* - * 5-level paging is detected and enabled at kernel decomression + * 5-level paging is detected and enabled at kernel decompression * stage. Only check if it has been enabled there. */ if (!(native_read_cr4() & X86_CR4_LA57)) @@ -104,6 +127,49 @@ static bool __head check_la57_support(unsigned long physaddr) } #endif +static unsigned long __head sme_postprocess_startup(struct boot_params *bp, pmdval_t *pmd) +{ + unsigned long vaddr, vaddr_end; + int i; + + /* Encrypt the kernel and related (if SME is active) */ + sme_encrypt_kernel(bp); + + /* + * Clear the memory encryption mask from the .bss..decrypted section. + * The bss section will be memset to zero later in the initialization so + * there is no need to zero it after changing the memory encryption + * attribute. + */ + if (sme_get_me_mask()) { + vaddr = (unsigned long)__start_bss_decrypted; + vaddr_end = (unsigned long)__end_bss_decrypted; + + for (; vaddr < vaddr_end; vaddr += PMD_SIZE) { + /* + * On SNP, transition the page to shared in the RMP table so that + * it is consistent with the page table attribute change. + * + * __start_bss_decrypted has a virtual address in the high range + * mapping (kernel .text). PVALIDATE, by way of + * early_snp_set_memory_shared(), requires a valid virtual + * address but the kernel is currently running off of the identity + * mapping so use __pa() to get a *currently* valid virtual address. + */ + early_snp_set_memory_shared(__pa(vaddr), __pa(vaddr), PTRS_PER_PMD); + + i = pmd_index(vaddr); + pmd[i] -= sme_get_me_mask(); + } + } + + /* + * Return the SME encryption mask (if SME is active) to be used as a + * modifier for the initial pgdir entry programmed into CR3. + */ + return sme_get_me_mask(); +} + /* Code in __startup_64() can be relocated during execution, but the compiler * doesn't have to generate PC-relative relocations when accessing globals from * that function. Clang actually does not generate them, which leads to @@ -113,7 +179,6 @@ static bool __head check_la57_support(unsigned long physaddr) unsigned long __head __startup_64(unsigned long physaddr, struct boot_params *bp) { - unsigned long vaddr, vaddr_end; unsigned long load_delta, *p; unsigned long pgtable_flags; pgdval_t *pgd; @@ -141,9 +206,6 @@ unsigned long __head __startup_64(unsigned long physaddr, if (load_delta & ~PMD_PAGE_MASK) for (;;); - /* Activate Secure Memory Encryption (SME) if supported and enabled */ - sme_enable(bp); - /* Include the SME encryption mask in the fixup value */ load_delta += sme_get_me_mask(); @@ -254,38 +316,7 @@ unsigned long __head __startup_64(unsigned long physaddr, */ *fixup_long(&phys_base, physaddr) += load_delta - sme_get_me_mask(); - /* Encrypt the kernel and related (if SME is active) */ - sme_encrypt_kernel(bp); - - /* - * Clear the memory encryption mask from the .bss..decrypted section. - * The bss section will be memset to zero later in the initialization so - * there is no need to zero it after changing the memory encryption - * attribute. - */ - if (mem_encrypt_active()) { - vaddr = (unsigned long)__start_bss_decrypted; - vaddr_end = (unsigned long)__end_bss_decrypted; - for (; vaddr < vaddr_end; vaddr += PMD_SIZE) { - i = pmd_index(vaddr); - pmd[i] -= sme_get_me_mask(); - } - } - - /* - * Return the SME encryption mask (if SME is active) to be used as a - * modifier for the initial pgdir entry programmed into CR3. - */ - return sme_get_me_mask(); -} - -unsigned long __startup_secondary_64(void) -{ - /* - * Return the SME encryption mask (if SME is active) to be used as a - * modifier for the initial pgdir entry programmed into CR3. - */ - return sme_get_me_mask(); + return sme_postprocess_startup(bp, pmd); } /* Wipe all early page tables except for the kernel symbol map */ @@ -297,7 +328,7 @@ static void __init reset_early_page_tables(void) } /* Create a new PMD entry */ -int __init __early_make_pgtable(unsigned long address, pmdval_t pmd) +bool __init __early_make_pgtable(unsigned long address, pmdval_t pmd) { unsigned long physaddr = address - __PAGE_OFFSET; pgdval_t pgd, *pgd_p; @@ -307,7 +338,7 @@ int __init __early_make_pgtable(unsigned long address, pmdval_t pmd) /* Invalid address or early pgt is done ? */ if (physaddr >= MAXMEM || read_cr3_pa() != __pa_nodebug(early_top_pgt)) - return -1; + return false; again: pgd_p = &early_top_pgt[pgd_index(address)].pgd; @@ -364,10 +395,10 @@ again: } pmd_p[pmd_index(address)] = pmd; - return 0; + return true; } -int __init early_make_pgtable(unsigned long address) +static bool __init early_make_pgtable(unsigned long address) { unsigned long physaddr = address - __PAGE_OFFSET; pmdval_t pmd; @@ -377,12 +408,30 @@ int __init early_make_pgtable(unsigned long address) return __early_make_pgtable(address, pmd); } +void __init do_early_exception(struct pt_regs *regs, int trapnr) +{ + if (trapnr == X86_TRAP_PF && + early_make_pgtable(native_read_cr2())) + return; + + if (IS_ENABLED(CONFIG_AMD_MEM_ENCRYPT) && + trapnr == X86_TRAP_VC && handle_vc_boot_ghcb(regs)) + return; + + if (trapnr == X86_TRAP_VE && tdx_early_handle_ve(regs)) + return; + + early_fixup_exception(regs, trapnr); +} + /* Don't add a printk in there. printk relies on the PDA which is not initialized yet. */ -static void __init clear_bss(void) +void __init clear_bss(void) { memset(__bss_start, 0, (unsigned long) __bss_stop - (unsigned long) __bss_start); + memset(__brk_base, 0, + (unsigned long) __brk_limit - (unsigned long) __brk_base); } static unsigned long get_cmd_line_ptr(void) @@ -445,6 +494,10 @@ asmlinkage __visible void __init x86_64_start_kernel(char * real_mode_data) clear_bss(); + /* + * This needs to happen *before* kasan_early_init() because latter maps stuff + * into that page. + */ clear_page(init_top_pgt); /* @@ -456,8 +509,21 @@ asmlinkage __visible void __init x86_64_start_kernel(char * real_mode_data) kasan_early_init(); + /* + * Flush global TLB entries which could be left over from the trampoline page + * table. + * + * This needs to happen *after* kasan_early_init() as KASAN-enabled .configs + * instrument native_write_cr4() so KASAN must be initialized for that + * instrumentation to work. + */ + __native_tlb_flush_global(this_cpu_read(cpu_tlbstate.cr4)); + idt_setup_early_handler(); + /* Needed before cc_platform_has() can be used for TDX */ + tdx_early_init(); + copy_bootdata(__va(real_mode_data)); /* @@ -489,3 +555,83 @@ void __init x86_64_start_reservations(char *real_mode_data) start_kernel(); } + +/* + * Data structures and code used for IDT setup in head_64.S. The bringup-IDT is + * used until the idt_table takes over. On the boot CPU this happens in + * x86_64_start_kernel(), on secondary CPUs in start_secondary(). In both cases + * this happens in the functions called from head_64.S. + * + * The idt_table can't be used that early because all the code modifying it is + * in idt.c and can be instrumented by tracing or KASAN, which both don't work + * during early CPU bringup. Also the idt_table has the runtime vectors + * configured which require certain CPU state to be setup already (like TSS), + * which also hasn't happened yet in early CPU bringup. + */ +static gate_desc bringup_idt_table[NUM_EXCEPTION_VECTORS] __page_aligned_data; + +static struct desc_ptr bringup_idt_descr = { + .size = (NUM_EXCEPTION_VECTORS * sizeof(gate_desc)) - 1, + .address = 0, /* Set at runtime */ +}; + +static void set_bringup_idt_handler(gate_desc *idt, int n, void *handler) +{ +#ifdef CONFIG_AMD_MEM_ENCRYPT + struct idt_data data; + gate_desc desc; + + init_idt_data(&data, n, handler); + idt_init_desc(&desc, &data); + native_write_idt_entry(idt, n, &desc); +#endif +} + +/* This runs while still in the direct mapping */ +static void startup_64_load_idt(unsigned long physbase) +{ + struct desc_ptr *desc = fixup_pointer(&bringup_idt_descr, physbase); + gate_desc *idt = fixup_pointer(bringup_idt_table, physbase); + + + if (IS_ENABLED(CONFIG_AMD_MEM_ENCRYPT)) { + void *handler; + + /* VMM Communication Exception */ + handler = fixup_pointer(vc_no_ghcb, physbase); + set_bringup_idt_handler(idt, X86_TRAP_VC, handler); + } + + desc->address = (unsigned long)idt; + native_load_idt(desc); +} + +/* This is used when running on kernel addresses */ +void early_setup_idt(void) +{ + /* VMM Communication Exception */ + if (IS_ENABLED(CONFIG_AMD_MEM_ENCRYPT)) { + setup_ghcb(); + set_bringup_idt_handler(bringup_idt_table, X86_TRAP_VC, vc_boot_ghcb); + } + + bringup_idt_descr.address = (unsigned long)bringup_idt_table; + native_load_idt(&bringup_idt_descr); +} + +/* + * Setup boot CPU state needed before kernel switches to virtual addresses. + */ +void __head startup_64_setup_env(unsigned long physbase) +{ + /* Load GDT */ + startup_gdt_descr.address = (unsigned long)fixup_pointer(startup_gdt, physbase); + native_load_gdt(&startup_gdt_descr); + + /* New GDT is live - reload data segment registers */ + asm volatile("movl %%eax, %%ds\n" + "movl %%eax, %%ss\n" + "movl %%eax, %%es\n" : : "a"(__KERNEL_DS) : "memory"); + + startup_64_load_idt(physbase); +} |