/*
* AMD Memory Encryption Support
*
* Copyright (C) 2016 Advanced Micro Devices, Inc.
*
* Author: Tom Lendacky <thomas.lendacky@amd.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#define DISABLE_BRANCH_PROFILING
#include <linux/linkage.h>
#include <linux/init.h>
#include <linux/mm.h>
#include <linux/dma-mapping.h>
#include <linux/swiotlb.h>
#include <linux/mem_encrypt.h>
#include <asm/tlbflush.h>
#include <asm/fixmap.h>
#include <asm/setup.h>
#include <asm/bootparam.h>
#include <asm/set_memory.h>
#include <asm/cacheflush.h>
#include <asm/sections.h>
#include <asm/processor-flags.h>
#include <asm/msr.h>
#include <asm/cmdline.h>
static char sme_cmdline_arg[] __initdata = "mem_encrypt";
static char sme_cmdline_on[] __initdata = "on";
static char sme_cmdline_off[] __initdata = "off";
/*
* Since SME related variables are set early in the boot process they must
* reside in the .data section so as not to be zeroed out when the .bss
* section is later cleared.
*/
u64 sme_me_mask __section(.data) = 0;
EXPORT_SYMBOL_GPL(sme_me_mask);
static bool sev_enabled __section(.data);
/* Buffer used for early in-place encryption by BSP, no locking needed */
static char sme_early_buffer[PAGE_SIZE] __aligned(PAGE_SIZE);
/*
* This routine does not change the underlying encryption setting of the
* page(s) that map this memory. It assumes that eventually the memory is
* meant to be accessed as either encrypted or decrypted but the contents
* are currently not in the desired state.
*
* This routine follows the steps outlined in the AMD64 Architecture
* Programmer's Manual Volume 2, Section 7.10.8 Encrypt-in-Place.
*/
static void __init __sme_early_enc_dec(resource_size_t paddr,
unsigned long size, bool enc)
{
void *src, *dst;
size_t len;
if (!sme_me_mask)
return;
local_flush_tlb();
wbinvd();
/*
* There are limited number of early mapping slots, so map (at most)
* one page at time.
*/
while (size) {
len = min_t(size_t, sizeof(sme_early_buffer), size);
/*
* Create mappings for the current and desired format of
* the memory. Use a write-protected mapping for the source.
*/
src = enc ? early_memremap_decrypted_wp(paddr, len) :
early_memremap_encrypted_wp(paddr, len);
dst = enc ? early_memremap_encrypted(paddr, len) :
early_memremap_decrypted(paddr, len);
/*
* If a mapping can't be obtained to perform the operation,
* then eventual access of that area in the desired mode
* will cause a crash.
*/
BUG_ON(!src || !dst);
/*
* Use a temporary buffer, of cache-line multiple size, to
* avoid data corruption as documented in the APM.
*/
memcpy(sme_early_buffer, src, len);
memcpy(dst, sme_early_buffer, len);
early_memunmap(dst, len);
early_memunmap(src, len);
paddr += len;
size -= len;
}
}
void __init sme_early_encrypt(resource_size_t paddr, unsigned long size)
{
__sme_early_enc_dec(paddr, size, true);
}
void __init sme_early_decrypt(resource_size_t paddr, unsigned long size)
{
__sme_early_enc_dec(paddr, size, false);
}
static void __init __sme_early_map_unmap_mem(void *vaddr, unsigned long size,
bool map)
{
unsigned long paddr = (unsigned long)vaddr - __PAGE_OFFSET;
pmdval_t pmd_flags, pmd;
/* Use early_pmd_flags but remove the encryption mask */
pmd_flags = __sme_clr(early_pmd_flags);
do {
pmd = map ? (paddr & PMD_MASK) + pmd_flags : 0;
__early_make_pgtable((unsigned long)vaddr, pmd);
vaddr += PMD_SIZE;
paddr += PMD_SIZE;
size = (size <= PMD_SIZE) ? 0 : size - PMD_SIZE;
} while (size);
__native_flush_tlb();
}
void __init sme_unmap_bootdata(char *real_mode_data)
{
struct boot_params *boot_data;
unsigned long cmdline_paddr;
if (!sme_active())
return;
/* Get the command line address before unmapping the real_mode_data */
boot_data = (struct boot_params *)real_mode_data;
cmdline_paddr = boot_data->hdr.cmd_line_ptr | ((u64)boot_data->ext_cmd_line_ptr << 32);
__sme_early_map_unmap_mem(real_mode_data, sizeof(boot_params), false);
if (!cmdline_paddr)
return;
__sme_early_map_unmap_mem(__va(cmdline_paddr), COMMAND_LINE_SIZE, false);
}
void __init sme_map_bootdata(char *real_mode_data)
{
struct boot_params *boot_data;
unsigned long cmdline_paddr;
if (!sme_active())
return;
__sme_early_map_unmap_mem(real_mode_data, sizeof(boot_params), true);
/* Get the command line address after mapping the real_mode_data */
boot_data = (struct boot_params *)real_mode_data;
cmdline_paddr = boot_data->hdr.cmd_line_ptr | ((u64)boot_data->ext_cmd_line_ptr << 32);
if (!cmdline_paddr)
return;
__sme_early_map_unmap_mem(__va(cmdline_paddr), COMMAND_LINE_SIZE, true);
}
void __init sme_early_init(void)
{
unsigned int i;
if (!sme_me_mask)
return;
early_pmd_flags = __sme_set(early_pmd_flags);
__supported_pte_mask = __sme_set(__supported_pte_mask);
/* Update the protection map with memory encryption mask */
for (i = 0; i < ARRAY_SIZE(protection_map); i++)
protection_map[i] = pgprot_encrypted(protection_map[i]);
}
/*
* SME and SEV are very similar but they are not the same, so there are
* times that the kernel will need to distinguish between SME and SEV. The
* sme_active() and sev_active() functions are used for this. When a
* distinction isn't needed, the mem_encrypt_active() function can be used.
*
* The trampoline code is a good example for this requirement. Before
* paging is activated, SME will access all memory as decrypted, but SEV
* will access all memory as encrypted. So, when APs are being brought
* up under SME the trampoline area cannot be encrypted, whereas under SEV
* the trampoline area must be encrypted.
*/
bool sme_active(void)
{
return sme_me_mask && !sev_enabled;
}
EXPORT_SYMBOL_GPL(sme_active);
bool sev_active(void)
{
return sme_me_mask && sev_enabled;
}
EXPORT_SYMBOL_GPL(sev_active);
/* Architecture __weak replacement functions */
void __init mem_encrypt_init(void)
{
if (!sme_me_mask)
return;
/* Call into SWIOTLB to update the SWIOTLB DMA buffers */
swiotlb_update_mem_attributes();
pr_info("AMD Secure Memory Encryption (SME) active\n");
}
void swiotlb_set_mem_attributes(void *vaddr, unsigned long size)
{
WARN(PAGE_ALIGN(size) != size,
"size is not page-aligned (%#lx)\n", size);
/* Make the SWIOTLB buffer area decrypted */
set_memory_decrypted((unsigned long)vaddr, size >> PAGE_SHIFT);
}
static void __init sme_clear_pgd(pgd_t *pgd_base, unsigned long start,
unsigned long end)
{
unsigned long pgd_start, pgd_end, pgd_size;
pgd_t *pgd_p;
pgd_start = start & PGDIR_MASK;
pgd_end = end & PGDIR_MASK;
pgd_size = (((pgd_end - pgd_start) / PGDIR_SIZE) + 1);
pgd_size *= sizeof(pgd_t);
pgd_p = pgd_base + pgd_index(start);
memset(pgd_p, 0, pgd_size);
}
#define PGD_FLAGS _KERNPG_TABLE_NOENC
#define P4D_FLAGS _KERNPG_TABLE_NOENC
#define PUD_FLAGS _KERNPG_TABLE_NOENC
#define PMD_FLAGS (__PAGE_KERNEL_LARGE_EXEC & ~_PAGE_GLOBAL)
static void __init *sme_populate_pgd(pgd_t *pgd_base, void *pgtable_area,
unsigned long vaddr, pmdval_t pmd_val)
{
pgd_t *pgd_p;
p4d_t *p4d_p;
pud_t *pud_p;
pmd_t *pmd_p;
pgd_p = pgd_base + pgd_index(vaddr);
if (native_pgd_val(*pgd_p)) {
if (IS_ENABLED(CONFIG_X86_5LEVEL))
p4d_p = (p4d_t *)(native_pgd_val(*pgd_p) & ~PTE_FLAGS_MASK);
else
pud_p = (pud_t *)(native_pgd_val(*pgd_p) & ~PTE_FLAGS_MASK);
} else {
pgd_t pgd;
if (IS_ENABLED(CONFIG_X86_5LEVEL)) {
p4d_p = pgtable_area;
memset(p4d_p, 0, sizeof(*p4d_p) * PTRS_PER_P4D);
pgtable_area += sizeof(*p4d_p) * PTRS_PER_P4D;
pgd = native_make_pgd((pgdval_t)p4d_p + PGD_FLAGS);
} else {
pud_p = pgtable_area;
memset(pud_p, 0, sizeof(*pud_p) * PTRS_PER_PUD);
pgtable_area += sizeof(*pud_p) * PTRS_PER_PUD;
pgd = native_make_pgd((pgdval_t)pud_p + PGD_FLAGS);
}
native_set_pgd(pgd_p, pgd);
}
if (IS_ENABLED(CONFIG_X86_5LEVEL)) {
p4d_p += p4d_index(vaddr);
if (native_p4d_val(*p4d_p)) {
pud_p = (pud_t *)(native_p4d_val(*p4d_p) & ~PTE_FLAGS_MASK);
} else {
p4d_t p4d;
pud_p = pgtable_area;
memset(pud_p, 0, sizeof(*pud_p) * PTRS_PER_PUD);
pgtable_area += sizeof(*pud_p) * PTRS_PER_PUD;
p4d = native_make_p4d((pudval_t)pud_p + P4D_FLAGS);
native_set_p4d(p4d_p, p4d);
}
}
pud_p += pud_index(vaddr);
if (native_pud_val(*pud_p)) {
if (native_pud_val(*pud_p) & _PAGE_PSE)
goto out;
pmd_p = (pmd_t *)(native_pud_val(*pud_p) & ~PTE_FLAGS_MASK);
} else {
pud_t pud;
pmd_p = pgtable_area;
memset(pmd_p, 0, sizeof(*pmd_p) * PTRS_PER_PMD);
pgtable_area += sizeof(*pmd_p) * PTRS_PER_PMD;
pud = native_make_pud((pmdval_t)pmd_p + PUD_FLAGS);
native_set_pud(pud_p, pud);
}
pmd_p += pmd_index(vaddr);
if (!native_pmd_val(*pmd_p) || !(native_pmd_val(*pmd_p) & _PAGE_PSE))
native_set_pmd(pmd_p, native_make_pmd(pmd_val));
out:
return pgtable_area;
}
static unsigned long __init sme_pgtable_calc(unsigned long len)
{
unsigned long p4d_size, pud_size, pmd_size;
unsigned long total;
/*
* Perform a relatively simplistic calculation of the pagetable
* entries that are needed. That mappings will be covered by 2MB
* PMD entries so we can conservatively calculate the required
* number of P4D, PUD and PMD structures needed to perform the
* mappings. Incrementing the count for each covers the case where
* the addresses cross entries.
*/
if (IS_ENABLED(CONFIG_X86_5LEVEL)) {
p4d_size = (ALIGN(len, PGDIR_SIZE) / PGDIR_SIZE) + 1;
p4d_size *= sizeof(p4d_t) * PTRS_PER_P4D;
pud_size = (ALIGN(len, P4D_SIZE) / P4D_SIZE) + 1;
pud_size *= sizeof(pud_t) * PTRS_PER_PUD;
} else {
p4d_size = 0;
pud_size = (ALIGN(len, PGDIR_SIZE) / PGDIR_SIZE) + 1;
pud_size *= sizeof(pud_t) * PTRS_PER_PUD;
}
pmd_size = (ALIGN(len, PUD_SIZE) / PUD_SIZE) + 1;
pmd_size *= sizeof(pmd_t) * PTRS_PER_PMD;
total = p4d_size + pud_size + pmd_size;
/*
* Now calculate the added pagetable structures needed to populate
* the new pagetables.
*/
if (IS_ENABLED(CONFIG_X86_5LEVEL)) {
p4d_size = ALIGN(total, PGDIR_SIZE) / PGDIR_SIZE;
p4d_size *= sizeof(p4d_t) * PTRS_PER_P4D;
pud_size = ALIGN(total, P4D_SIZE) / P4D_SIZE;
pud_size *= sizeof(pud_t) * PTRS_PER_PUD;
} else {
p4d_size = 0;
pud_size = ALIGN(total, PGDIR_SIZE) / PGDIR_SIZE;
pud_size *= sizeof(pud_t) * PTRS_PER_PUD;
}
pmd_size = ALIGN(total, PUD_SIZE) / PUD_SIZE;
pmd_size *= sizeof(pmd_t) * PTRS_PER_PMD;
total += p4d_size + pud_size + pmd_size;
return total;
}
void __init sme_encrypt_kernel(void)
{
unsigned long workarea_start, workarea_end, workarea_len;
unsigned long execute_start, execute_end, execute_len;
unsigned long kernel_start, kernel_end, kernel_len;
unsigned long pgtable_area_len;
unsigned long paddr, pmd_flags;
unsigned long decrypted_base;
void *pgtable_area;
pgd_t *pgd;
if (!sme_active())
return;
/*
* Prepare for encrypting the kernel by building new pagetables with
* the necessary attributes needed to encrypt the kernel in place.
*
* One range of virtual addresses will map the memory occupied
* by the kernel as encrypted.
*
* Another range of virtual addresses will map the memory occupied
* by the kernel as decrypted and write-protected.
*
* The use of write-protect attribute will prevent any of the
* memory from being cached.
*/
/* Physical addresses gives us the identity mapped virtual addresses */
kernel_start = __pa_symbol(_text);
kernel_end = ALIGN(__pa_symbol(_end), PMD_PAGE_SIZE);
kernel_len = kernel_end - kernel_start;
/* Set the encryption workarea to be immediately after the kernel */
workarea_start = kernel_end;
/*
* Calculate required number of workarea bytes needed:
* executable encryption area size:
* stack page (PAGE_SIZE)
* encryption routine page (PAGE_SIZE)
* intermediate copy buffer (PMD_PAGE_SIZE)
* pagetable structures for the encryption of the kernel
* pagetable structures for workarea (in case not currently mapped)
*/
execute_start = workarea_start;
execute_end = execute_start + (PAGE_SIZE * 2) + PMD_PAGE_SIZE;
execute_len = execute_end - execute_start;
/*
* One PGD for both encrypted and decrypted mappings and a set of
* PUDs and PMDs for each of the encrypted and decrypted mappings.
*/
pgtable_area_len = sizeof(pgd_t) * PTRS_PER_PGD;
pgtable_area_len += sme_pgtable_calc(execute_end - kernel_start) * 2;
/* PUDs and PMDs needed in the current pagetables for the workarea */
pgtable_area_len += sme_pgtable_calc(execute_len + pgtable_area_len);
/*
* The total workarea includes the executable encryption area and
* the pagetable area.
*/
workarea_len = execute_len + pgtable_area_len;
workarea_end = workarea_start + workarea_len;
/*
* Set the address to the start of where newly created pagetable
* structures (PGDs, PUDs and PMDs) will be allocated. New pagetable
* structures are created when the workarea is added to the current
* pagetables and when the new encrypted and decrypted kernel
* mappings are populated.
*/
pgtable_area = (void *)execute_end;
/*
* Make sure the current pagetable structure has entries for
* addressing the workarea.
*/
pgd = (pgd_t *)native_read_cr3_pa();
paddr = workarea_start;
while (paddr < workarea_end) {
pgtable_area = sme_populate_pgd(pgd, pgtable_area,
paddr,
paddr + PMD_FLAGS);
paddr += PMD_PAGE_SIZE;
}
/* Flush the TLB - no globals so cr3 is enough */
native_write_cr3(__native_read_cr3());
/*
* A new pagetable structure is being built to allow for the kernel
* to be encrypted. It starts with an empty PGD that will then be
* populated with new PUDs and PMDs as the encrypted and decrypted
* kernel mappings are created.
*/
pgd = pgtable_area;
memset(pgd, 0, sizeof(*pgd) * PTRS_PER_PGD);
pgtable_area += sizeof(*pgd) * PTRS_PER_PGD;
/* Add encrypted kernel (identity) mappings */
pmd_flags = PMD_FLAGS | _PAGE_ENC;
paddr = kernel_start;
while (paddr < kernel_end) {
pgtable_area = sme_populate_pgd(pgd, pgtable_area,
paddr,
paddr + pmd_flags);
paddr += PMD_PAGE_SIZE;
}
/*
* A different PGD index/entry must be used to get different
* pagetable entries for the decrypted mapping. Choose the next
* PGD index and convert it to a virtual address to be used as
* the base of the mapping.
*/
decrypted_base = (pgd_index(workarea_end) + 1) & (PTRS_PER_PGD - 1);
decrypted_base <<= PGDIR_SHIFT;
/* Add decrypted, write-protected kernel (non-identity) mappings */
pmd_flags = (PMD_FLAGS & ~_PAGE_CACHE_MASK) | (_PAGE_PAT | _PAGE_PWT);
paddr = kernel_start;
while (paddr < kernel_end) {
pgtable_area = sme_populate_pgd(pgd, pgtable_area,
paddr + decrypted_base,
paddr + pmd_flags);
paddr += PMD_PAGE_SIZE;
}
/* Add decrypted workarea mappings to both kernel mappings */
paddr = workarea_start;
while (paddr < workarea_end) {
pgtable_area = sme_populate_pgd(pgd, pgtable_area,
paddr,
paddr + PMD_FLAGS);
pgtable_area = sme_populate_pgd(pgd, pgtable_area,
paddr + decrypted_base,
paddr + PMD_FLAGS);
paddr += PMD_PAGE_SIZE;
}
/* Perform the encryption */
sme_encrypt_execute(kernel_start, kernel_start + decrypted_base,
kernel_len, workarea_start, (unsigned long)pgd);
/*
* At this point we are running encrypted. Remove the mappings for
* the decrypted areas - all that is needed for this is to remove
* the PGD entry/entries.
*/
sme_clear_pgd(pgd, kernel_start + decrypted_base,
kernel_end + decrypted_base);
sme_clear_pgd(pgd, workarea_start + decrypted_base,
workarea_end + decrypted_base);
/* Flush the TLB - no globals so cr3 is enough */
native_write_cr3(__native_read_cr3());
}
void __init __nostackprotector sme_enable(struct boot_params *bp)
{
const char *cmdline_ptr, *cmdline_arg, *cmdline_on, *cmdline_off;
unsigned int eax, ebx, ecx, edx;
bool active_by_default;
unsigned long me_mask;
char buffer[16];
u64 msr;
/* Check for the SME support leaf */
eax = 0x80000000;
ecx = 0;
native_cpuid(&eax, &ebx, &ecx, &edx);
if (eax < 0x8000001f)
return;
/*
* Check for the SME feature:
* CPUID Fn8000_001F[EAX] - Bit 0
* Secure Memory Encryption support
* CPUID Fn8000_001F[EBX] - Bits 5:0
* Pagetable bit position used to indicate encryption
*/
eax = 0x8000001f;
ecx = 0;
native_cpuid(&eax, &ebx, &ecx, &edx);
if (!(eax & 1))
return;
me_mask = 1UL << (ebx & 0x3f);
/* Check if SME is enabled */
msr = __rdmsr(MSR_K8_SYSCFG);
if (!(msr & MSR_K8_SYSCFG_MEM_ENCRYPT))
return;
/*
* Fixups have not been applied to phys_base yet and we're running
* identity mapped, so we must obtain the address to the SME command
* line argument data using rip-relative addressing.
*/
asm ("lea sme_cmdline_arg(%%rip), %0"
: "=r" (cmdline_arg)
: "p" (sme_cmdline_arg));
asm ("lea sme_cmdline_on(%%rip), %0"
: "=r" (cmdline_on)
: "p" (sme_cmdline_on));
asm ("lea sme_cmdline_off(%%rip), %0"
: "=r" (cmdline_off)
: "p" (sme_cmdline_off));
if (IS_ENABLED(CONFIG_AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT))
active_by_default = true;
else
active_by_default = false;
cmdline_ptr = (const char *)((u64)bp->hdr.cmd_line_ptr |
((u64)bp->ext_cmd_line_ptr << 32));
cmdline_find_option(cmdline_ptr, cmdline_arg, buffer, sizeof(buffer));
if (!strncmp(buffer, cmdline_on, sizeof(buffer)))
sme_me_mask = me_mask;
else if (!strncmp(buffer, cmdline_off, sizeof(buffer)))
sme_me_mask = 0;
else
sme_me_mask = active_by_default ? me_mask : 0;
}
