164 lines · c
1// SPDX-License-Identifier: GPL-2.0-only2#include "linux/types.h"3#include "linux/bitmap.h"4#include "linux/atomic.h"5 6#include "kvm_util.h"7#include "ucall_common.h"8 9 10#define GUEST_UCALL_FAILED -111 12struct ucall_header {13 DECLARE_BITMAP(in_use, KVM_MAX_VCPUS);14 struct ucall ucalls[KVM_MAX_VCPUS];15};16 17int ucall_nr_pages_required(uint64_t page_size)18{19 return align_up(sizeof(struct ucall_header), page_size) / page_size;20}21 22/*23 * ucall_pool holds per-VM values (global data is duplicated by each VM), it24 * must not be accessed from host code.25 */26static struct ucall_header *ucall_pool;27 28void ucall_init(struct kvm_vm *vm, vm_paddr_t mmio_gpa)29{30 struct ucall_header *hdr;31 struct ucall *uc;32 vm_vaddr_t vaddr;33 int i;34 35 vaddr = vm_vaddr_alloc_shared(vm, sizeof(*hdr), KVM_UTIL_MIN_VADDR,36 MEM_REGION_DATA);37 hdr = (struct ucall_header *)addr_gva2hva(vm, vaddr);38 memset(hdr, 0, sizeof(*hdr));39 40 for (i = 0; i < KVM_MAX_VCPUS; ++i) {41 uc = &hdr->ucalls[i];42 uc->hva = uc;43 }44 45 write_guest_global(vm, ucall_pool, (struct ucall_header *)vaddr);46 47 ucall_arch_init(vm, mmio_gpa);48}49 50static struct ucall *ucall_alloc(void)51{52 struct ucall *uc;53 int i;54 55 if (!ucall_pool)56 goto ucall_failed;57 58 for (i = 0; i < KVM_MAX_VCPUS; ++i) {59 if (!test_and_set_bit(i, ucall_pool->in_use)) {60 uc = &ucall_pool->ucalls[i];61 memset(uc->args, 0, sizeof(uc->args));62 return uc;63 }64 }65 66ucall_failed:67 /*68 * If the vCPU cannot grab a ucall structure, make a bare ucall with a69 * magic value to signal to get_ucall() that things went sideways.70 * GUEST_ASSERT() depends on ucall_alloc() and so cannot be used here.71 */72 ucall_arch_do_ucall(GUEST_UCALL_FAILED);73 return NULL;74}75 76static void ucall_free(struct ucall *uc)77{78 /* Beware, here be pointer arithmetic. */79 clear_bit(uc - ucall_pool->ucalls, ucall_pool->in_use);80}81 82void ucall_assert(uint64_t cmd, const char *exp, const char *file,83 unsigned int line, const char *fmt, ...)84{85 struct ucall *uc;86 va_list va;87 88 uc = ucall_alloc();89 uc->cmd = cmd;90 91 WRITE_ONCE(uc->args[GUEST_ERROR_STRING], (uint64_t)(exp));92 WRITE_ONCE(uc->args[GUEST_FILE], (uint64_t)(file));93 WRITE_ONCE(uc->args[GUEST_LINE], line);94 95 va_start(va, fmt);96 guest_vsnprintf(uc->buffer, UCALL_BUFFER_LEN, fmt, va);97 va_end(va);98 99 ucall_arch_do_ucall((vm_vaddr_t)uc->hva);100 101 ucall_free(uc);102}103 104void ucall_fmt(uint64_t cmd, const char *fmt, ...)105{106 struct ucall *uc;107 va_list va;108 109 uc = ucall_alloc();110 uc->cmd = cmd;111 112 va_start(va, fmt);113 guest_vsnprintf(uc->buffer, UCALL_BUFFER_LEN, fmt, va);114 va_end(va);115 116 ucall_arch_do_ucall((vm_vaddr_t)uc->hva);117 118 ucall_free(uc);119}120 121void ucall(uint64_t cmd, int nargs, ...)122{123 struct ucall *uc;124 va_list va;125 int i;126 127 uc = ucall_alloc();128 129 WRITE_ONCE(uc->cmd, cmd);130 131 nargs = min(nargs, UCALL_MAX_ARGS);132 133 va_start(va, nargs);134 for (i = 0; i < nargs; ++i)135 WRITE_ONCE(uc->args[i], va_arg(va, uint64_t));136 va_end(va);137 138 ucall_arch_do_ucall((vm_vaddr_t)uc->hva);139 140 ucall_free(uc);141}142 143uint64_t get_ucall(struct kvm_vcpu *vcpu, struct ucall *uc)144{145 struct ucall ucall;146 void *addr;147 148 if (!uc)149 uc = &ucall;150 151 addr = ucall_arch_get_ucall(vcpu);152 if (addr) {153 TEST_ASSERT(addr != (void *)GUEST_UCALL_FAILED,154 "Guest failed to allocate ucall struct");155 156 memcpy(uc, addr, sizeof(*uc));157 vcpu_run_complete_io(vcpu);158 } else {159 memset(uc, 0, sizeof(*uc));160 }161 162 return uc->cmd;163}164