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