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
arm_smccc_do_one_page(u32 func_id,phys_addr_t phys)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
__set_memory_range(u32 func_id,unsigned long start,int numpages)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
pkvm_set_memory_encrypted(unsigned long addr,int numpages)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
pkvm_set_memory_decrypted(unsigned long addr,int numpages)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
mmio_guard_ioremap_hook(phys_addr_t phys,size_t size,pgprot_t * prot)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
pkvm_init_hyp_services(void)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