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