1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Support for the hypercall interface exposed to protected guests by 4 * pKVM. 5 * 6 * Author: Will Deacon <will@kernel.org> 7 * Copyright (C) 2024 Google LLC 8 */ 9 10 #include <linux/arm-smccc.h> 11 #include <linux/array_size.h> 12 #include <linux/io.h> 13 #include <linux/mem_encrypt.h> 14 #include <linux/mm.h> 15 #include <linux/pgtable.h> 16 17 #include <asm/hypervisor.h> 18 19 static size_t pkvm_granule; 20 21 static int arm_smccc_do_one_page(u32 func_id, phys_addr_t phys) 22 { 23 phys_addr_t end = phys + PAGE_SIZE; 24 25 while (phys < end) { 26 struct arm_smccc_res res; 27 28 arm_smccc_1_1_invoke(func_id, phys, 0, 0, &res); 29 if (res.a0 != SMCCC_RET_SUCCESS) 30 return -EPERM; 31 32 phys += pkvm_granule; 33 } 34 35 return 0; 36 } 37 38 static int __set_memory_range(u32 func_id, unsigned long start, int numpages) 39 { 40 void *addr = (void *)start, *end = addr + numpages * PAGE_SIZE; 41 42 while (addr < end) { 43 int err; 44 45 err = arm_smccc_do_one_page(func_id, virt_to_phys(addr)); 46 if (err) 47 return err; 48 49 addr += PAGE_SIZE; 50 } 51 52 return 0; 53 } 54 55 static int pkvm_set_memory_encrypted(unsigned long addr, int numpages) 56 { 57 return __set_memory_range(ARM_SMCCC_VENDOR_HYP_KVM_MEM_UNSHARE_FUNC_ID, 58 addr, numpages); 59 } 60 61 static int pkvm_set_memory_decrypted(unsigned long addr, int numpages) 62 { 63 return __set_memory_range(ARM_SMCCC_VENDOR_HYP_KVM_MEM_SHARE_FUNC_ID, 64 addr, numpages); 65 } 66 67 static const struct arm64_mem_crypt_ops pkvm_crypt_ops = { 68 .encrypt = pkvm_set_memory_encrypted, 69 .decrypt = pkvm_set_memory_decrypted, 70 }; 71 72 static int mmio_guard_ioremap_hook(phys_addr_t phys, size_t size, 73 pgprot_t *prot) 74 { 75 phys_addr_t end; 76 pteval_t protval = pgprot_val(*prot); 77 78 /* 79 * We only expect MMIO emulation for regions mapped with device 80 * attributes. 81 */ 82 if (protval != PROT_DEVICE_nGnRE && protval != PROT_DEVICE_nGnRnE) 83 return 0; 84 85 phys = PAGE_ALIGN_DOWN(phys); 86 end = phys + PAGE_ALIGN(size); 87 88 while (phys < end) { 89 const int func_id = ARM_SMCCC_VENDOR_HYP_KVM_MMIO_GUARD_FUNC_ID; 90 int err; 91 92 err = arm_smccc_do_one_page(func_id, phys); 93 if (err) 94 return err; 95 96 phys += PAGE_SIZE; 97 } 98 99 return 0; 100 } 101 102 void pkvm_init_hyp_services(void) 103 { 104 int i; 105 struct arm_smccc_res res; 106 const u32 funcs[] = { 107 ARM_SMCCC_KVM_FUNC_HYP_MEMINFO, 108 ARM_SMCCC_KVM_FUNC_MEM_SHARE, 109 ARM_SMCCC_KVM_FUNC_MEM_UNSHARE, 110 }; 111 112 for (i = 0; i < ARRAY_SIZE(funcs); ++i) { 113 if (!kvm_arm_hyp_service_available(funcs[i])) 114 return; 115 } 116 117 arm_smccc_1_1_invoke(ARM_SMCCC_VENDOR_HYP_KVM_HYP_MEMINFO_FUNC_ID, 118 0, 0, 0, &res); 119 if (res.a0 > PAGE_SIZE) /* Includes error codes */ 120 return; 121 122 pkvm_granule = res.a0; 123 arm64_mem_crypt_ops_register(&pkvm_crypt_ops); 124 125 if (kvm_arm_hyp_service_available(ARM_SMCCC_KVM_FUNC_MMIO_GUARD)) 126 arm64_ioremap_prot_hook_register(&mmio_guard_ioremap_hook); 127 } 128