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libsel4vm: guest cpu requests to vcpus from pcpus #85

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libsel4vm: guest cpu requests to vcpus from pcpus #85

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23 changes: 23 additions & 0 deletions libsel4vm/include/sel4vm/guest_vm_util.h
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Original file line number Diff line number Diff line change
Expand Up @@ -72,6 +72,29 @@ static inline vm_vcpu_t *vm_find_free_unassigned_vcpu(vm_t *vm)
return NULL;
}

/***
* @function vm_find_free_unassigned_cpu(vm)
* Find an unallocated physical cpu
* @param {vm_t *} vm A handle to the vm owning the vcpu
* @return -1 if no pcpu can be found, otherwise the available pcpu
*/
static inline int vm_find_free_unassigned_cpu(vm_t *vm)
{
for (int core = 0; core < CONFIG_MAX_NUM_NODES; core++) {
int core_allocated = 0;
for (int i = 0; i < vm->num_vcpus; i++) {
if (vm->vcpus[i]->target_cpu == core) {
core_allocated = 1;
break;
}
}
if (!core_allocated) {
return core;
}
}
return -1;
}

/***
* @function is_vcpu_online(vcpu)
* Find if a given VCPU is online
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19 changes: 14 additions & 5 deletions libsel4vmmplatsupport/src/arch/arm/psci.c
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Expand Up @@ -50,15 +50,24 @@ int handle_psci(vm_vcpu_t *vcpu, seL4_Word fn_number, bool convention)
smc_set_return_value(&regs, 0x00010000); /* version 1 */
break;
case PSCI_CPU_ON: {
uintptr_t target_cpu = smc_get_arg(&regs, 1);
uintptr_t requested_cpu = smc_get_arg(&regs, 1);
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so, my question holds - we get a (v)MPIDR here from the guest and not a linear (seL4 affinity) ID?

uintptr_t entry_point_address = smc_get_arg(&regs, 2);
uintptr_t context_id = smc_get_arg(&regs, 3);
vm_vcpu_t *target_vcpu = vm_vcpu_for_target_cpu(vcpu->vm, target_cpu);
if (target_vcpu == NULL) {
target_vcpu = vm_find_free_unassigned_vcpu(vcpu->vm);
if (target_vcpu && start_new_vcpu(target_vcpu, entry_point_address, context_id, target_cpu) == 0) {
vm_vcpu_t *target_vcpu = NULL;
if ((requested_cpu >= 0) && (requested_cpu < vcpu->vm->num_vcpus)) {
target_vcpu = vcpu->vm->vcpus[requested_cpu];
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This will not work, because requested_cpu is a MPID value now - because that is what a caller passed into the SMC according to the spec. So we need to do a lookup over all our vCPUs.

} else {
smc_set_return_value(&regs, PSCI_INTERNAL_FAILURE);
break;
}

/* Automatically assign vcpu to an unassigned physical cpu */
if (target_vcpu->target_cpu == -1) {
int selected_cpu = vm_find_free_unassigned_cpu(vcpu->vm);
if ((selected_cpu >= 0) && start_new_vcpu(target_vcpu, entry_point_address, context_id, selected_cpu) == 0) {
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Don't we have to set the MPIDR of the vCPU here also now, so this is in sync with what the caller requested? Can the caller actually starts arbitrary cored here - shouldn't we have prepared the vCPU list in advance, about what cores the caller can start, ie. what cores the VM has.

smc_set_return_value(&regs, PSCI_SUCCESS);
} else {
ZF_LOGE("[vCPU %u] no unused physical core left", vcpu->vcpu_id);
smc_set_return_value(&regs, PSCI_INTERNAL_FAILURE);
}
} else {
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