124 lines
2.7 KiB
C
124 lines
2.7 KiB
C
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// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Support for the hypercall interface exposed to protected guests by
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* pKVM.
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*
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* Author: Will Deacon <will@kernel.org>
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* Copyright (C) 2024 Google LLC
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*/
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#include <linux/arm-smccc.h>
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#include <linux/array_size.h>
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#include <linux/io.h>
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#include <linux/mem_encrypt.h>
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#include <linux/mm.h>
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#include <linux/pgtable.h>
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#include <asm/hypervisor.h>
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static size_t pkvm_granule;
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static int arm_smccc_do_one_page(u32 func_id, phys_addr_t phys)
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{
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phys_addr_t end = phys + PAGE_SIZE;
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while (phys < end) {
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struct arm_smccc_res res;
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arm_smccc_1_1_invoke(func_id, phys, 0, 0, &res);
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if (res.a0 != SMCCC_RET_SUCCESS)
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return -EPERM;
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phys += pkvm_granule;
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}
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return 0;
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}
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static int __set_memory_range(u32 func_id, unsigned long start, int numpages)
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{
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void *addr = (void *)start, *end = addr + numpages * PAGE_SIZE;
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while (addr < end) {
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int err;
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err = arm_smccc_do_one_page(func_id, virt_to_phys(addr));
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if (err)
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return err;
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addr += PAGE_SIZE;
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}
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return 0;
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}
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static int pkvm_set_memory_encrypted(unsigned long addr, int numpages)
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{
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return __set_memory_range(ARM_SMCCC_VENDOR_HYP_KVM_MEM_UNSHARE_FUNC_ID,
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addr, numpages);
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}
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static int pkvm_set_memory_decrypted(unsigned long addr, int numpages)
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{
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return __set_memory_range(ARM_SMCCC_VENDOR_HYP_KVM_MEM_SHARE_FUNC_ID,
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addr, numpages);
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}
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static const struct arm64_mem_crypt_ops pkvm_crypt_ops = {
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.encrypt = pkvm_set_memory_encrypted,
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.decrypt = pkvm_set_memory_decrypted,
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};
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static int mmio_guard_ioremap_hook(phys_addr_t phys, size_t size,
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pgprot_t *prot)
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{
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phys_addr_t end;
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pteval_t protval = pgprot_val(*prot);
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/*
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* We only expect MMIO emulation for regions mapped with device
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* attributes.
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*/
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if (protval != PROT_DEVICE_nGnRE && protval != PROT_DEVICE_nGnRnE)
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return 0;
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phys = PAGE_ALIGN_DOWN(phys);
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end = phys + PAGE_ALIGN(size);
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while (phys < end) {
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const int func_id = ARM_SMCCC_VENDOR_HYP_KVM_MMIO_GUARD_FUNC_ID;
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WARN_ON_ONCE(arm_smccc_do_one_page(func_id, phys));
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phys += PAGE_SIZE;
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}
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return 0;
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}
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void pkvm_init_hyp_services(void)
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{
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int i;
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struct arm_smccc_res res;
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const u32 funcs[] = {
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ARM_SMCCC_KVM_FUNC_HYP_MEMINFO,
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ARM_SMCCC_KVM_FUNC_MEM_SHARE,
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ARM_SMCCC_KVM_FUNC_MEM_UNSHARE,
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};
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for (i = 0; i < ARRAY_SIZE(funcs); ++i) {
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if (!kvm_arm_hyp_service_available(funcs[i]))
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return;
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}
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arm_smccc_1_1_invoke(ARM_SMCCC_VENDOR_HYP_KVM_HYP_MEMINFO_FUNC_ID,
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0, 0, 0, &res);
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if (res.a0 > PAGE_SIZE) /* Includes error codes */
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return;
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pkvm_granule = res.a0;
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arm64_mem_crypt_ops_register(&pkvm_crypt_ops);
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if (kvm_arm_hyp_service_available(ARM_SMCCC_KVM_FUNC_MMIO_GUARD))
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arm64_ioremap_prot_hook_register(&mmio_guard_ioremap_hook);
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}
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