| // SPDX-License-Identifier: GPL-2.0-only |
| /* |
| * AMD Memory Encryption Support |
| * |
| * Copyright (C) 2016 Advanced Micro Devices, Inc. |
| * |
| * Author: Tom Lendacky <thomas.lendacky@amd.com> |
| */ |
| |
| #define DISABLE_BRANCH_PROFILING |
| |
| #include <linux/linkage.h> |
| #include <linux/init.h> |
| #include <linux/mm.h> |
| #include <linux/dma-direct.h> |
| #include <linux/swiotlb.h> |
| #include <linux/mem_encrypt.h> |
| #include <linux/device.h> |
| #include <linux/kernel.h> |
| #include <linux/bitops.h> |
| #include <linux/dma-mapping.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/processor-flags.h> |
| #include <asm/msr.h> |
| #include <asm/cmdline.h> |
| |
| #include "mm_internal.h" |
| |
| /* |
| * 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(sme_me_mask); |
| DEFINE_STATIC_KEY_FALSE(sev_enable_key); |
| EXPORT_SYMBOL_GPL(sev_enable_key); |
| |
| bool sev_enabled __section(.data); |
| |
| /* Buffer used for early in-place encryption by BSP, no locking needed */ |
| static char sme_early_buffer[PAGE_SIZE] __initdata __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; |
| |
| 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]); |
| |
| if (sev_active()) |
| swiotlb_force = SWIOTLB_FORCE; |
| } |
| |
| static void __init __set_clr_pte_enc(pte_t *kpte, int level, bool enc) |
| { |
| pgprot_t old_prot, new_prot; |
| unsigned long pfn, pa, size; |
| pte_t new_pte; |
| |
| switch (level) { |
| case PG_LEVEL_4K: |
| pfn = pte_pfn(*kpte); |
| old_prot = pte_pgprot(*kpte); |
| break; |
| case PG_LEVEL_2M: |
| pfn = pmd_pfn(*(pmd_t *)kpte); |
| old_prot = pmd_pgprot(*(pmd_t *)kpte); |
| break; |
| case PG_LEVEL_1G: |
| pfn = pud_pfn(*(pud_t *)kpte); |
| old_prot = pud_pgprot(*(pud_t *)kpte); |
| break; |
| default: |
| return; |
| } |
| |
| new_prot = old_prot; |
| if (enc) |
| pgprot_val(new_prot) |= _PAGE_ENC; |
| else |
| pgprot_val(new_prot) &= ~_PAGE_ENC; |
| |
| /* If prot is same then do nothing. */ |
| if (pgprot_val(old_prot) == pgprot_val(new_prot)) |
| return; |
| |
| pa = pfn << PAGE_SHIFT; |
| size = page_level_size(level); |
| |
| /* |
| * We are going to perform in-place en-/decryption and change the |
| * physical page attribute from C=1 to C=0 or vice versa. Flush the |
| * caches to ensure that data gets accessed with the correct C-bit. |
| */ |
| clflush_cache_range(__va(pa), size); |
| |
| /* Encrypt/decrypt the contents in-place */ |
| if (enc) |
| sme_early_encrypt(pa, size); |
| else |
| sme_early_decrypt(pa, size); |
| |
| /* Change the page encryption mask. */ |
| new_pte = pfn_pte(pfn, new_prot); |
| set_pte_atomic(kpte, new_pte); |
| } |
| |
| static int __init early_set_memory_enc_dec(unsigned long vaddr, |
| unsigned long size, bool enc) |
| { |
| unsigned long vaddr_end, vaddr_next; |
| unsigned long psize, pmask; |
| int split_page_size_mask; |
| int level, ret; |
| pte_t *kpte; |
| |
| vaddr_next = vaddr; |
| vaddr_end = vaddr + size; |
| |
| for (; vaddr < vaddr_end; vaddr = vaddr_next) { |
| kpte = lookup_address(vaddr, &level); |
| if (!kpte || pte_none(*kpte)) { |
| ret = 1; |
| goto out; |
| } |
| |
| if (level == PG_LEVEL_4K) { |
| __set_clr_pte_enc(kpte, level, enc); |
| vaddr_next = (vaddr & PAGE_MASK) + PAGE_SIZE; |
| continue; |
| } |
| |
| psize = page_level_size(level); |
| pmask = page_level_mask(level); |
| |
| /* |
| * Check whether we can change the large page in one go. |
| * We request a split when the address is not aligned and |
| * the number of pages to set/clear encryption bit is smaller |
| * than the number of pages in the large page. |
| */ |
| if (vaddr == (vaddr & pmask) && |
| ((vaddr_end - vaddr) >= psize)) { |
| __set_clr_pte_enc(kpte, level, enc); |
| vaddr_next = (vaddr & pmask) + psize; |
| continue; |
| } |
| |
| /* |
| * The virtual address is part of a larger page, create the next |
| * level page table mapping (4K or 2M). If it is part of a 2M |
| * page then we request a split of the large page into 4K |
| * chunks. A 1GB large page is split into 2M pages, resp. |
| */ |
| if (level == PG_LEVEL_2M) |
| split_page_size_mask = 0; |
| else |
| split_page_size_mask = 1 << PG_LEVEL_2M; |
| |
| /* |
| * kernel_physical_mapping_change() does not flush the TLBs, so |
| * a TLB flush is required after we exit from the for loop. |
| */ |
| kernel_physical_mapping_change(__pa(vaddr & pmask), |
| __pa((vaddr_end & pmask) + psize), |
| split_page_size_mask); |
| } |
| |
| ret = 0; |
| |
| out: |
| __flush_tlb_all(); |
| return ret; |
| } |
| |
| int __init early_set_memory_decrypted(unsigned long vaddr, unsigned long size) |
| { |
| return early_set_memory_enc_dec(vaddr, size, false); |
| } |
| |
| int __init early_set_memory_encrypted(unsigned long vaddr, unsigned long size) |
| { |
| return early_set_memory_enc_dec(vaddr, size, true); |
| } |
| |
| /* |
| * 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; |
| } |
| |
| bool sev_active(void) |
| { |
| return sme_me_mask && sev_enabled; |
| } |
| |
| /* Override for DMA direct allocation check - ARCH_HAS_FORCE_DMA_UNENCRYPTED */ |
| bool force_dma_unencrypted(struct device *dev) |
| { |
| /* |
| * For SEV, all DMA must be to unencrypted addresses. |
| */ |
| if (sev_active()) |
| return true; |
| |
| /* |
| * For SME, all DMA must be to unencrypted addresses if the |
| * device does not support DMA to addresses that include the |
| * encryption mask. |
| */ |
| if (sme_active()) { |
| u64 dma_enc_mask = DMA_BIT_MASK(__ffs64(sme_me_mask)); |
| u64 dma_dev_mask = min_not_zero(dev->coherent_dma_mask, |
| dev->bus_dma_mask); |
| |
| if (dma_dev_mask <= dma_enc_mask) |
| return true; |
| } |
| |
| return false; |
| } |
| EXPORT_SYMBOL_GPL(sev_active); |
| |
| /* Architecture __weak replacement functions */ |
| void __init mem_encrypt_free_decrypted_mem(void) |
| { |
| unsigned long vaddr, vaddr_end, npages; |
| int r; |
| |
| vaddr = (unsigned long)__start_bss_decrypted_unused; |
| vaddr_end = (unsigned long)__end_bss_decrypted; |
| npages = (vaddr_end - vaddr) >> PAGE_SHIFT; |
| |
| /* |
| * The unused memory range was mapped decrypted, change the encryption |
| * attribute from decrypted to encrypted before freeing it. |
| */ |
| if (mem_encrypt_active()) { |
| r = set_memory_encrypted(vaddr, npages); |
| if (r) { |
| pr_warn("failed to free unused decrypted pages\n"); |
| return; |
| } |
| } |
| |
| free_init_pages("unused decrypted", vaddr, vaddr_end); |
| } |
| |
| void __init mem_encrypt_init(void) |
| { |
| if (!sme_me_mask) |
| return; |
| |
| /* Call into SWIOTLB to update the SWIOTLB DMA buffers */ |
| swiotlb_update_mem_attributes(); |
| |
| /* |
| * With SEV, we need to unroll the rep string I/O instructions. |
| */ |
| if (sev_active()) |
| static_branch_enable(&sev_enable_key); |
| |
| pr_info("AMD %s active\n", |
| sev_active() ? "Secure Encrypted Virtualization (SEV)" |
| : "Secure Memory Encryption (SME)"); |
| } |
| |