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// SPDX-License-Identifier: GPL-2.0
#include <linux/io.h>
#include <linux/slab.h>
#include <linux/memblock.h>
#include <linux/cc_platform.h>
#include <linux/pgtable.h>
#include <asm/set_memory.h>
#include <asm/realmode.h>
#include <asm/tlbflush.h>
#include <asm/crash.h>
#include <asm/sev.h>
struct real_mode_header *real_mode_header;
u32 *trampoline_cr4_features;
/* Hold the pgd entry used on booting additional CPUs */
pgd_t trampoline_pgd_entry;
void load_trampoline_pgtable(void)
{
#ifdef CONFIG_X86_32
load_cr3(initial_page_table);
#else
/*
* This function is called before exiting to real-mode and that will
* fail with CR4.PCIDE still set.
*/
if (boot_cpu_has(X86_FEATURE_PCID))
cr4_clear_bits(X86_CR4_PCIDE);
write_cr3(real_mode_header->trampoline_pgd);
#endif
/*
* The CR3 write above will not flush global TLB entries.
* Stale, global entries from previous page tables may still be
* present. Flush those stale entries.
*
* This ensures that memory accessed while running with
* trampoline_pgd is *actually* mapped into trampoline_pgd.
*/
__flush_tlb_all();
}
void __init reserve_real_mode(void)
{
phys_addr_t mem;
size_t size = real_mode_size_needed();
if (!size)
return;
WARN_ON(slab_is_available());
/* Has to be under 1M so we can execute real-mode AP code. */
mem = memblock_phys_alloc_range(size, PAGE_SIZE, 0, 1<<20);
if (!mem)
pr_info("No sub-1M memory is available for the trampoline\n");
else
set_real_mode_mem(mem);
/*
* Unconditionally reserve the entire fisrt 1M, see comment in
* setup_arch().
*/
memblock_reserve(0, SZ_1M);
}
static void __init sme_sev_setup_real_mode(struct trampoline_header *th)
{
#ifdef CONFIG_AMD_MEM_ENCRYPT
if (cc_platform_has(CC_ATTR_HOST_MEM_ENCRYPT))
th->flags |= TH_FLAGS_SME_ACTIVE;
if (cc_platform_has(CC_ATTR_GUEST_STATE_ENCRYPT)) {
/*
* Skip the call to verify_cpu() in secondary_startup_64 as it
* will cause #VC exceptions when the AP can't handle them yet.
*/
th->start = (u64) secondary_startup_64_no_verify;
if (sev_es_setup_ap_jump_table(real_mode_header))
panic("Failed to get/update SEV-ES AP Jump Table");
}
#endif
}
static void __init setup_real_mode(void)
{
u16 real_mode_seg;
const u32 *rel;
u32 count;
unsigned char *base;
unsigned long phys_base;
struct trampoline_header *trampoline_header;
size_t size = PAGE_ALIGN(real_mode_blob_end - real_mode_blob);
#ifdef CONFIG_X86_64
u64 *trampoline_pgd;
u64 efer;
int i;
#endif
base = (unsigned char *)real_mode_header;
/*
* If SME is active, the trampoline area will need to be in
* decrypted memory in order to bring up other processors
* successfully. This is not needed for SEV.
*/
if (cc_platform_has(CC_ATTR_HOST_MEM_ENCRYPT))
set_memory_decrypted((unsigned long)base, size >> PAGE_SHIFT);
memcpy(base, real_mode_blob, size);
phys_base = __pa(base);
real_mode_seg = phys_base >> 4;
rel = (u32 *) real_mode_relocs;
/* 16-bit segment relocations. */
count = *rel++;
while (count--) {
u16 *seg = (u16 *) (base + *rel++);
*seg = real_mode_seg;
}
/* 32-bit linear relocations. */
count = *rel++;
while (count--) {
u32 *ptr = (u32 *) (base + *rel++);
*ptr += phys_base;
}
/* Must be performed *after* relocation. */
trampoline_header = (struct trampoline_header *)
__va(real_mode_header->trampoline_header);
#ifdef CONFIG_X86_32
trampoline_header->start = __pa_symbol(startup_32_smp);
trampoline_header->gdt_limit = __BOOT_DS + 7;
trampoline_header->gdt_base = __pa_symbol(boot_gdt);
#else
/*
* Some AMD processors will #GP(0) if EFER.LMA is set in WRMSR
* so we need to mask it out.
*/
rdmsrl(MSR_EFER, efer);
trampoline_header->efer = efer & ~EFER_LMA;
trampoline_header->start = (u64) secondary_startup_64;
trampoline_cr4_features = &trampoline_header->cr4;
*trampoline_cr4_features = mmu_cr4_features;
trampoline_header->flags = 0;
trampoline_lock = &trampoline_header->lock;
*trampoline_lock = 0;
trampoline_pgd = (u64 *) __va(real_mode_header->trampoline_pgd);
/* Map the real mode stub as virtual == physical */
trampoline_pgd[0] = trampoline_pgd_entry.pgd;
/*
* Include the entirety of the kernel mapping into the trampoline
* PGD. This way, all mappings present in the normal kernel page
* tables are usable while running on trampoline_pgd.
*/
for (i = pgd_index(__PAGE_OFFSET); i < PTRS_PER_PGD; i++)
trampoline_pgd[i] = init_top_pgt[i].pgd;
#endif
sme_sev_setup_real_mode(trampoline_header);
}
/*
* reserve_real_mode() gets called very early, to guarantee the
* availability of low memory. This is before the proper kernel page
* tables are set up, so we cannot set page permissions in that
* function. Also trampoline code will be executed by APs so we
* need to mark it executable at do_pre_smp_initcalls() at least,
* thus run it as a early_initcall().
*/
static void __init set_real_mode_permissions(void)
{
unsigned char *base = (unsigned char *) real_mode_header;
size_t size = PAGE_ALIGN(real_mode_blob_end - real_mode_blob);
size_t ro_size =
PAGE_ALIGN(real_mode_header->ro_end) -
__pa(base);
size_t text_size =
PAGE_ALIGN(real_mode_header->ro_end) -
real_mode_header->text_start;
unsigned long text_start =
(unsigned long) __va(real_mode_header->text_start);
set_memory_nx((unsigned long) base, size >> PAGE_SHIFT);
set_memory_ro((unsigned long) base, ro_size >> PAGE_SHIFT);
set_memory_x((unsigned long) text_start, text_size >> PAGE_SHIFT);
}
void __init init_real_mode(void)
{
if (!real_mode_header)
panic("Real mode trampoline was not allocated");
setup_real_mode();
set_real_mode_permissions();
}
static int __init do_init_real_mode(void)
{
x86_platform.realmode_init();
return 0;
}
early_initcall(do_init_real_mode);
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