/*
 * Assuming that we need a unique ASID per vcpu. This may not be necessary
 * if the TLB entries mapping guest_linear -> host_physical are also tagged
 * as belonging to a particular vcpu (e.g. with the VMCB physical address).
 */

uint32_t max_asid;

struct asid {
	uint32_t	num;		/* 0 is reserved for the host */
	uint64_t	generation;	/* 0 is invalid */
};

static struct asid host_asid[MAXCPU];

struct svm_vcpu {
	/* Cached value of 'pmap->nptgen'. Must be initialized to 0. */
	long nptgen[MAXCPU];

	/* ASID value of this vcpu. Must be initialized to 0. */
	struct asid asid[MAXCPU];
};

asid_init()
{
	foreach host cpu {
		host_asid[cpu].num = 1;
		host_asid[cpu].generation = 1;
	}
}

int
check_asid(struct asid *guest_asid)
{
	uint32_t next;
	int flushall = 0;

	KASSERT(inside_critical_section);

	if (guest_asid->generation != host_asid[curcpu].generation) {
		if (host_asid[curcpu].num >= max_asid) {
			flushall = 1;
			host_asid[curcpu].num = 1;
			host_asid[curcpu].generation++;
		}

		guest_asid->generation = host_asid[curcpu].generation;
		guest_asid->num = host_asid[curcpu].num++;
		assert(guest_asid->num > 0 && guest_asid->num < max_asid);
	}

	return (flushall);
}

void
invalidate_asid(struct asid *guest_asid)
{
	guest_asid->generation = 0;		/* invalid generation */
}

vm_loop()
{
	disable_gintr();

	pmap->pm_active |= (1 << curcpu);

	flush_guest = 0;
	nptgen = pmap->nptgen;

	/* Invalidate stale mappings from when we last ran on this cpu */
	if (vcpustate->lastcpu != curcpu)
		flush_guest = 1;

	/* Invalidate stale mappings because the nested mappings have changed */
	if (vcpustate->nptgen[curcpu] != nptgen) {
		flush_guest = 1;
		vcpustate->nptgen[curcpu] = nptgen;
	}

	if (flush_guest)
		invalidate_asid(&vcpustate->asid[curcpu]);

	flush_all = check_asid(&vcpustate->asid[curcpu]);

	if (flush_all)
		ctrl->tlb_ctrl = TLB_FLUSH_ALL;
	else
		ctrl->tlb_ctrl = TLB_FLUSH_NOTHING;

	pmap->pm_active &= ~(1 << curcpu);

	enable_gintr();
}