1 // SPDX-License-Identifier: GPL-2.0-only 2 #include <asm/trap_pf.h> 3 #include <asm/segment.h> 4 #include <asm/trapnr.h> 5 #include "misc.h" 6 7 static void set_idt_entry(int vector, void (*handler)(void)) 8 { 9 unsigned long address = (unsigned long)handler; 10 gate_desc entry; 11 12 memset(&entry, 0, sizeof(entry)); 13 14 entry.offset_low = (u16)(address & 0xffff); 15 entry.segment = __KERNEL_CS; 16 entry.bits.type = GATE_TRAP; 17 entry.bits.p = 1; 18 entry.offset_middle = (u16)((address >> 16) & 0xffff); 19 entry.offset_high = (u32)(address >> 32); 20 21 memcpy(&boot_idt[vector], &entry, sizeof(entry)); 22 } 23 24 /* Have this here so we don't need to include <asm/desc.h> */ 25 static void load_boot_idt(const struct desc_ptr *dtr) 26 { 27 asm volatile("lidt %0"::"m" (*dtr)); 28 } 29 30 /* Setup IDT before kernel jumping to .Lrelocated */ 31 void load_stage1_idt(void) 32 { 33 boot_idt_desc.address = (unsigned long)boot_idt; 34 35 36 if (IS_ENABLED(CONFIG_AMD_MEM_ENCRYPT)) 37 set_idt_entry(X86_TRAP_VC, boot_stage1_vc); 38 39 load_boot_idt(&boot_idt_desc); 40 } 41 42 /* 43 * Setup IDT after kernel jumping to .Lrelocated. 44 * 45 * initialize_identity_maps() needs a #PF handler to be setup 46 * in order to be able to fault-in identity mapping ranges; see 47 * do_boot_page_fault(). 48 * 49 * This #PF handler setup needs to happen in load_stage2_idt() where the 50 * IDT is loaded and there the #VC IDT entry gets setup too. 51 * 52 * In order to be able to handle #VCs, one needs a GHCB which 53 * gets setup with an already set up pagetable, which is done in 54 * initialize_identity_maps(). And there's the catch 22: the boot #VC 55 * handler do_boot_stage2_vc() needs to call early_setup_ghcb() itself 56 * (and, especially set_page_decrypted()) because the SEV-ES setup code 57 * cannot initialize a GHCB as there's no #PF handler yet... 58 */ 59 void load_stage2_idt(void) 60 { 61 boot_idt_desc.address = (unsigned long)boot_idt; 62 63 set_idt_entry(X86_TRAP_PF, boot_page_fault); 64 65 #ifdef CONFIG_AMD_MEM_ENCRYPT 66 set_idt_entry(X86_TRAP_VC, boot_stage2_vc); 67 #endif 68 69 load_boot_idt(&boot_idt_desc); 70 } 71 72 void cleanup_exception_handling(void) 73 { 74 /* 75 * Flush GHCB from cache and map it encrypted again when running as 76 * SEV-ES guest. 77 */ 78 sev_es_shutdown_ghcb(); 79 80 /* Set a null-idt, disabling #PF and #VC handling */ 81 boot_idt_desc.size = 0; 82 boot_idt_desc.address = 0; 83 load_boot_idt(&boot_idt_desc); 84 } 85