116 lines
2.4 KiB
C
116 lines
2.4 KiB
C
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// SPDX-License-Identifier: GPL-2.0-only
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#include "kvm_util.h"
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#include "linux/types.h"
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#include "linux/bitmap.h"
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#include "linux/atomic.h"
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#define GUEST_UCALL_FAILED -1
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struct ucall_header {
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DECLARE_BITMAP(in_use, KVM_MAX_VCPUS);
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struct ucall ucalls[KVM_MAX_VCPUS];
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};
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/*
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* ucall_pool holds per-VM values (global data is duplicated by each VM), it
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* must not be accessed from host code.
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*/
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static struct ucall_header *ucall_pool;
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void ucall_init(struct kvm_vm *vm, vm_paddr_t mmio_gpa)
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{
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struct ucall_header *hdr;
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struct ucall *uc;
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vm_vaddr_t vaddr;
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int i;
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vaddr = __vm_vaddr_alloc(vm, sizeof(*hdr), KVM_UTIL_MIN_VADDR, MEM_REGION_DATA);
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hdr = (struct ucall_header *)addr_gva2hva(vm, vaddr);
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memset(hdr, 0, sizeof(*hdr));
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for (i = 0; i < KVM_MAX_VCPUS; ++i) {
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uc = &hdr->ucalls[i];
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uc->hva = uc;
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}
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write_guest_global(vm, ucall_pool, (struct ucall_header *)vaddr);
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ucall_arch_init(vm, mmio_gpa);
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}
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static struct ucall *ucall_alloc(void)
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{
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struct ucall *uc;
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int i;
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if (!ucall_pool)
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goto ucall_failed;
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for (i = 0; i < KVM_MAX_VCPUS; ++i) {
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if (!test_and_set_bit(i, ucall_pool->in_use)) {
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uc = &ucall_pool->ucalls[i];
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memset(uc->args, 0, sizeof(uc->args));
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return uc;
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}
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}
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ucall_failed:
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/*
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* If the vCPU cannot grab a ucall structure, make a bare ucall with a
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* magic value to signal to get_ucall() that things went sideways.
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* GUEST_ASSERT() depends on ucall_alloc() and so cannot be used here.
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*/
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ucall_arch_do_ucall(GUEST_UCALL_FAILED);
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return NULL;
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}
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static void ucall_free(struct ucall *uc)
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{
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/* Beware, here be pointer arithmetic. */
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clear_bit(uc - ucall_pool->ucalls, ucall_pool->in_use);
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}
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void ucall(uint64_t cmd, int nargs, ...)
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{
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struct ucall *uc;
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va_list va;
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int i;
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uc = ucall_alloc();
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WRITE_ONCE(uc->cmd, cmd);
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nargs = min(nargs, UCALL_MAX_ARGS);
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va_start(va, nargs);
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for (i = 0; i < nargs; ++i)
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WRITE_ONCE(uc->args[i], va_arg(va, uint64_t));
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va_end(va);
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ucall_arch_do_ucall((vm_vaddr_t)uc->hva);
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ucall_free(uc);
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}
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uint64_t get_ucall(struct kvm_vcpu *vcpu, struct ucall *uc)
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{
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struct ucall ucall;
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void *addr;
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if (!uc)
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uc = &ucall;
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addr = ucall_arch_get_ucall(vcpu);
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if (addr) {
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TEST_ASSERT(addr != (void *)GUEST_UCALL_FAILED,
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"Guest failed to allocate ucall struct");
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memcpy(uc, addr, sizeof(*uc));
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vcpu_run_complete_io(vcpu);
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} else {
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memset(uc, 0, sizeof(*uc));
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}
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return uc->cmd;
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}
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