149 lines
3.8 KiB
C
Executable File
149 lines
3.8 KiB
C
Executable File
/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* Implementation of the memory encryption/decryption API.
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*
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* Amusingly, no crypto is actually performed. Rather, we call into the
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* hypervisor component of KVM to expose pages selectively to the host
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* for virtio "DMA" operations. In other words, "encrypted" pages are
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* not accessible to the host, whereas "decrypted" pages are.
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*
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* Author: Will Deacon <will@kernel.org>
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*/
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#include <linux/arm-smccc.h>
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#include <linux/mem_encrypt.h>
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#include <linux/memory.h>
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#include <linux/mm.h>
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#include <linux/set_memory.h>
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#include <linux/types.h>
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#include <asm/hypervisor.h>
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#ifndef ARM_SMCCC_KVM_FUNC_HYP_MEMINFO
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#define ARM_SMCCC_KVM_FUNC_HYP_MEMINFO 2
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#define ARM_SMCCC_VENDOR_HYP_KVM_HYP_MEMINFO_FUNC_ID \
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ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, \
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ARM_SMCCC_SMC_64, \
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ARM_SMCCC_OWNER_VENDOR_HYP, \
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ARM_SMCCC_KVM_FUNC_HYP_MEMINFO)
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#endif /* ARM_SMCCC_KVM_FUNC_HYP_MEMINFO */
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#ifndef ARM_SMCCC_KVM_FUNC_MEM_SHARE
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#define ARM_SMCCC_KVM_FUNC_MEM_SHARE 3
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#define ARM_SMCCC_VENDOR_HYP_KVM_MEM_SHARE_FUNC_ID \
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ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, \
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ARM_SMCCC_SMC_64, \
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ARM_SMCCC_OWNER_VENDOR_HYP, \
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ARM_SMCCC_KVM_FUNC_MEM_SHARE)
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#endif /* ARM_SMCCC_KVM_FUNC_MEM_SHARE */
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#ifndef ARM_SMCCC_KVM_FUNC_MEM_UNSHARE
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#define ARM_SMCCC_KVM_FUNC_MEM_UNSHARE 4
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#define ARM_SMCCC_VENDOR_HYP_KVM_MEM_UNSHARE_FUNC_ID \
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ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, \
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ARM_SMCCC_SMC_64, \
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ARM_SMCCC_OWNER_VENDOR_HYP, \
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ARM_SMCCC_KVM_FUNC_MEM_UNSHARE)
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#endif /* ARM_SMCCC_KVM_FUNC_MEM_UNSHARE */
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static unsigned long memshare_granule_sz;
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static bool memshare_has_range;
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bool mem_encrypt_active(void)
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{
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return memshare_granule_sz;
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}
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EXPORT_SYMBOL(mem_encrypt_active);
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void kvm_init_memshare_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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long ret;
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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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ret = (long)res.a0;
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if (ret < 0)
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return;
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memshare_has_range = res.a1 & KVM_FUNC_HAS_RANGE;
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memshare_granule_sz = ret;
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}
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static int __invoke_memshare(unsigned long addr, int nr_granules, int func_id,
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u64 *nr_xcrypted)
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{
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u64 nr_granules_arg = memshare_has_range ? nr_granules : 0;
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struct arm_smccc_res res;
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arm_smccc_1_1_invoke(func_id, virt_to_phys((void *)addr),
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nr_granules_arg, 0, &res);
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if (WARN_ON(res.a0 != SMCCC_RET_SUCCESS))
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return -EPERM;
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*nr_xcrypted = memshare_has_range ? res.a1 : 1;
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return 0;
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}
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static int set_memory_xcrypted(u32 func_id, unsigned long start, int numpages)
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{
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int nr_granules;
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if (!memshare_granule_sz)
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return 0;
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if (WARN_ON(!PAGE_ALIGNED(start)))
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return -EINVAL;
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/* Prevent over-sharing when memshare_granule_sz > PAGE_SIZE */
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if (!IS_ALIGNED(start, memshare_granule_sz) ||
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(PAGE_SIZE * numpages) % memshare_granule_sz)
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return -ERANGE;
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nr_granules = (numpages * PAGE_SIZE) / memshare_granule_sz;
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while (nr_granules > 0) {
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u64 nr_xcrypted;
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int ret;
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ret = __invoke_memshare(start, nr_granules, func_id, &nr_xcrypted);
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if (ret)
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return ret;
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WARN_ON(nr_xcrypted > nr_granules);
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nr_granules -= nr_xcrypted;
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start += nr_xcrypted * memshare_granule_sz;
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}
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return 0;
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}
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int set_memory_encrypted(unsigned long addr, int numpages)
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{
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return set_memory_xcrypted(ARM_SMCCC_VENDOR_HYP_KVM_MEM_UNSHARE_FUNC_ID,
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addr, numpages);
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}
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EXPORT_SYMBOL_GPL(set_memory_encrypted);
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int set_memory_decrypted(unsigned long addr, int numpages)
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{
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return set_memory_xcrypted(ARM_SMCCC_VENDOR_HYP_KVM_MEM_SHARE_FUNC_ID,
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addr, numpages);
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}
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EXPORT_SYMBOL_GPL(set_memory_decrypted);
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