From: David Woodhouse <dwmw@xxxxxxxxxxxx> A previous implementation of this stuff used a 64-bit field for all of the port information (vcpu/type/type_val) and did atomic exchanges on them. When I implemented that in Qemu I regretted my life choices and just kept it simple with locking instead. So there's no need for the XenEvtchnPort to be so simplistic. We can use a union for the pirq/virq/interdomain information, which lets us keep a separate bit for the 'remote domain' in interdomain ports. A single bit is enough since the only possible targets are loopback or qemu itself. So now we can ditch PORT_INFO_TYPEVAL_REMOTE_QEMU and the horrid manual masking, although the in-memory representation is identical so there's no change in the saved state ABI. Signed-off-by: David Woodhouse <dwmw@xxxxxxxxxxxx> Reviewed-by: Paul Durrant <paul@xxxxxxx> --- hw/i386/kvm/xen_evtchn.c | 151 ++++++++++++++++++--------------------- 1 file changed, 70 insertions(+), 81 deletions(-) diff --git a/hw/i386/kvm/xen_evtchn.c b/hw/i386/kvm/xen_evtchn.c index 3d6f4b4a0a..d72dca6591 100644 --- a/hw/i386/kvm/xen_evtchn.c +++ b/hw/i386/kvm/xen_evtchn.c @@ -58,7 +58,15 @@ OBJECT_DECLARE_SIMPLE_TYPE(XenEvtchnState, XEN_EVTCHN) typedef struct XenEvtchnPort { uint32_t vcpu; /* Xen/ACPI vcpu_id */ uint16_t type; /* EVTCHNSTAT_xxxx */ - uint16_t type_val; /* pirq# / virq# / remote port according to type */ + union { + uint16_t val; /* raw value for serialization etc. */ + uint16_t pirq; + uint16_t virq; + struct { + uint16_t port:15; + uint16_t to_qemu:1; /* Only two targets; qemu or loopback */ + } interdomain; + } u; } XenEvtchnPort; /* 32-bit compatibility definitions, also used natively in 32-bit build */ @@ -105,14 +113,6 @@ struct xenevtchn_handle { int fd; }; -/* - * For unbound/interdomain ports there are only two possible remote - * domains; self and QEMU. Use a single high bit in type_val for that, - * and the low bits for the remote port number (or 0 for unbound). - */ -#define PORT_INFO_TYPEVAL_REMOTE_QEMU 0x8000 -#define PORT_INFO_TYPEVAL_REMOTE_PORT_MASK 0x7FFF - /* * These 'emuirq' values are used by Xen in the LM stream... and yes, I am * insane enough to think about guest-transparent live migration from actual @@ -210,16 +210,16 @@ static int xen_evtchn_post_load(void *opaque, int version_id) XenEvtchnPort *p = &s->port_table[i]; if (p->type == EVTCHNSTAT_pirq) { - assert(p->type_val); - assert(p->type_val < s->nr_pirqs); + assert(p->u.pirq); + assert(p->u.pirq < s->nr_pirqs); /* * Set the gsi to IRQ_UNBOUND; it may be changed to an actual * GSI# below, or to IRQ_MSI_EMU when the MSI table snooping * catches up with it. */ - s->pirq[p->type_val].gsi = IRQ_UNBOUND; - s->pirq[p->type_val].port = i; + s->pirq[p->u.pirq].gsi = IRQ_UNBOUND; + s->pirq[p->u.pirq].port = i; } } /* Rebuild s->pirq[].gsi mapping */ @@ -243,7 +243,7 @@ static const VMStateDescription xen_evtchn_port_vmstate = { .fields = (VMStateField[]) { VMSTATE_UINT32(vcpu, XenEvtchnPort), VMSTATE_UINT16(type, XenEvtchnPort), - VMSTATE_UINT16(type_val, XenEvtchnPort), + VMSTATE_UINT16(u.val, XenEvtchnPort), VMSTATE_END_OF_LIST() } }; @@ -605,14 +605,13 @@ static void unbind_backend_ports(XenEvtchnState *s) for (i = 1; i < s->nr_ports; i++) { p = &s->port_table[i]; - if (p->type == EVTCHNSTAT_interdomain && - (p->type_val & PORT_INFO_TYPEVAL_REMOTE_QEMU)) { - evtchn_port_t be_port = p->type_val & PORT_INFO_TYPEVAL_REMOTE_PORT_MASK; + if (p->type == EVTCHNSTAT_interdomain && p->u.interdomain.to_qemu) { + evtchn_port_t be_port = p->u.interdomain.port; if (s->be_handles[be_port]) { /* This part will be overwritten on the load anyway. */ p->type = EVTCHNSTAT_unbound; - p->type_val = PORT_INFO_TYPEVAL_REMOTE_QEMU; + p->u.interdomain.port = 0; /* Leave the backend port open and unbound too. */ if (kvm_xen_has_cap(EVTCHN_SEND)) { @@ -650,30 +649,22 @@ int xen_evtchn_status_op(struct evtchn_status *status) switch (p->type) { case EVTCHNSTAT_unbound: - if (p->type_val & PORT_INFO_TYPEVAL_REMOTE_QEMU) { - status->u.unbound.dom = DOMID_QEMU; - } else { - status->u.unbound.dom = xen_domid; - } + status->u.unbound.dom = p->u.interdomain.to_qemu ? DOMID_QEMU + : xen_domid; break; case EVTCHNSTAT_interdomain: - if (p->type_val & PORT_INFO_TYPEVAL_REMOTE_QEMU) { - status->u.interdomain.dom = DOMID_QEMU; - } else { - status->u.interdomain.dom = xen_domid; - } - - status->u.interdomain.port = p->type_val & - PORT_INFO_TYPEVAL_REMOTE_PORT_MASK; + status->u.interdomain.dom = p->u.interdomain.to_qemu ? DOMID_QEMU + : xen_domid; + status->u.interdomain.port = p->u.interdomain.port; break; case EVTCHNSTAT_pirq: - status->u.pirq = p->type_val; + status->u.pirq = p->u.pirq; break; case EVTCHNSTAT_virq: - status->u.virq = p->type_val; + status->u.virq = p->u.virq; break; } @@ -989,7 +980,7 @@ static int clear_port_pending(XenEvtchnState *s, evtchn_port_t port) static void free_port(XenEvtchnState *s, evtchn_port_t port) { s->port_table[port].type = EVTCHNSTAT_closed; - s->port_table[port].type_val = 0; + s->port_table[port].u.val = 0; s->port_table[port].vcpu = 0; if (s->nr_ports == port + 1) { @@ -1012,7 +1003,7 @@ static int allocate_port(XenEvtchnState *s, uint32_t vcpu, uint16_t type, if (s->port_table[p].type == EVTCHNSTAT_closed) { s->port_table[p].vcpu = vcpu; s->port_table[p].type = type; - s->port_table[p].type_val = val; + s->port_table[p].u.val = val; *port = p; @@ -1053,15 +1044,15 @@ static int close_port(XenEvtchnState *s, evtchn_port_t port, return -ENOENT; case EVTCHNSTAT_pirq: - s->pirq[p->type_val].port = 0; - if (s->pirq[p->type_val].is_translated) { + s->pirq[p->u.pirq].port = 0; + if (s->pirq[p->u.pirq].is_translated) { *flush_kvm_routes = true; } break; case EVTCHNSTAT_virq: - kvm_xen_set_vcpu_virq(virq_is_global(p->type_val) ? 0 : p->vcpu, - p->type_val, 0); + kvm_xen_set_vcpu_virq(virq_is_global(p->u.virq) ? 0 : p->vcpu, + p->u.virq, 0); break; case EVTCHNSTAT_ipi: @@ -1071,8 +1062,8 @@ static int close_port(XenEvtchnState *s, evtchn_port_t port, break; case EVTCHNSTAT_interdomain: - if (p->type_val & PORT_INFO_TYPEVAL_REMOTE_QEMU) { - uint16_t be_port = p->type_val & ~PORT_INFO_TYPEVAL_REMOTE_QEMU; + if (p->u.interdomain.to_qemu) { + uint16_t be_port = p->u.interdomain.port; struct xenevtchn_handle *xc = s->be_handles[be_port]; if (xc) { if (kvm_xen_has_cap(EVTCHN_SEND)) { @@ -1082,14 +1073,15 @@ static int close_port(XenEvtchnState *s, evtchn_port_t port, } } else { /* Loopback interdomain */ - XenEvtchnPort *rp = &s->port_table[p->type_val]; - if (!valid_port(p->type_val) || rp->type_val != port || + XenEvtchnPort *rp = &s->port_table[p->u.interdomain.port]; + if (!valid_port(p->u.interdomain.port) || + rp->u.interdomain.port != port || rp->type != EVTCHNSTAT_interdomain) { error_report("Inconsistent state for interdomain unbind"); } else { /* Set the other end back to unbound */ rp->type = EVTCHNSTAT_unbound; - rp->type_val = 0; + rp->u.interdomain.port = 0; } } break; @@ -1213,7 +1205,7 @@ int xen_evtchn_bind_vcpu_op(struct evtchn_bind_vcpu *vcpu) if (p->type == EVTCHNSTAT_interdomain || p->type == EVTCHNSTAT_unbound || p->type == EVTCHNSTAT_pirq || - (p->type == EVTCHNSTAT_virq && virq_is_global(p->type_val))) { + (p->type == EVTCHNSTAT_virq && virq_is_global(p->u.virq))) { /* * unmask_port() with do_unmask==false will just raise the event * on the new vCPU if the port was already pending. @@ -1358,19 +1350,15 @@ int xen_evtchn_bind_ipi_op(struct evtchn_bind_ipi *ipi) int xen_evtchn_bind_interdomain_op(struct evtchn_bind_interdomain *interdomain) { XenEvtchnState *s = xen_evtchn_singleton; - uint16_t type_val; int ret; if (!s) { return -ENOTSUP; } - if (interdomain->remote_dom == DOMID_QEMU) { - type_val = PORT_INFO_TYPEVAL_REMOTE_QEMU; - } else if (interdomain->remote_dom == DOMID_SELF || - interdomain->remote_dom == xen_domid) { - type_val = 0; - } else { + if (interdomain->remote_dom != DOMID_QEMU && + interdomain->remote_dom != DOMID_SELF && + interdomain->remote_dom != xen_domid) { return -ESRCH; } @@ -1381,8 +1369,8 @@ int xen_evtchn_bind_interdomain_op(struct evtchn_bind_interdomain *interdomain) qemu_mutex_lock(&s->port_lock); /* The newly allocated port starts out as unbound */ - ret = allocate_port(s, 0, EVTCHNSTAT_unbound, type_val, - &interdomain->local_port); + ret = allocate_port(s, 0, EVTCHNSTAT_unbound, 0, &interdomain->local_port); + if (ret) { goto out; } @@ -1407,7 +1395,8 @@ int xen_evtchn_bind_interdomain_op(struct evtchn_bind_interdomain *interdomain) assign_kernel_eventfd(lp->type, xc->guest_port, xc->fd); } lp->type = EVTCHNSTAT_interdomain; - lp->type_val = PORT_INFO_TYPEVAL_REMOTE_QEMU | interdomain->remote_port; + lp->u.interdomain.to_qemu = 1; + lp->u.interdomain.port = interdomain->remote_port; ret = 0; } else { /* Loopback */ @@ -1415,19 +1404,18 @@ int xen_evtchn_bind_interdomain_op(struct evtchn_bind_interdomain *interdomain) XenEvtchnPort *lp = &s->port_table[interdomain->local_port]; /* - * The 'remote' port for loopback must be an unbound port allocated for - * communication with the local domain (as indicated by rp->type_val - * being zero, not PORT_INFO_TYPEVAL_REMOTE_QEMU), and must *not* be - * the port that was just allocated for the local end. + * The 'remote' port for loopback must be an unbound port allocated + * for communication with the local domain, and must *not* be the + * port that was just allocated for the local end. */ if (interdomain->local_port != interdomain->remote_port && - rp->type == EVTCHNSTAT_unbound && rp->type_val == 0) { + rp->type == EVTCHNSTAT_unbound && !rp->u.interdomain.to_qemu) { rp->type = EVTCHNSTAT_interdomain; - rp->type_val = interdomain->local_port; + rp->u.interdomain.port = interdomain->local_port; lp->type = EVTCHNSTAT_interdomain; - lp->type_val = interdomain->remote_port; + lp->u.interdomain.port = interdomain->remote_port; } else { ret = -EINVAL; } @@ -1446,7 +1434,6 @@ int xen_evtchn_bind_interdomain_op(struct evtchn_bind_interdomain *interdomain) int xen_evtchn_alloc_unbound_op(struct evtchn_alloc_unbound *alloc) { XenEvtchnState *s = xen_evtchn_singleton; - uint16_t type_val; int ret; if (!s) { @@ -1457,18 +1444,20 @@ int xen_evtchn_alloc_unbound_op(struct evtchn_alloc_unbound *alloc) return -ESRCH; } - if (alloc->remote_dom == DOMID_QEMU) { - type_val = PORT_INFO_TYPEVAL_REMOTE_QEMU; - } else if (alloc->remote_dom == DOMID_SELF || - alloc->remote_dom == xen_domid) { - type_val = 0; - } else { + if (alloc->remote_dom != DOMID_QEMU && + alloc->remote_dom != DOMID_SELF && + alloc->remote_dom != xen_domid) { return -EPERM; } qemu_mutex_lock(&s->port_lock); - ret = allocate_port(s, 0, EVTCHNSTAT_unbound, type_val, &alloc->port); + ret = allocate_port(s, 0, EVTCHNSTAT_unbound, 0, &alloc->port); + + if (!ret && alloc->remote_dom == DOMID_QEMU) { + XenEvtchnPort *p = &s->port_table[alloc->port]; + p->u.interdomain.to_qemu = 1; + } qemu_mutex_unlock(&s->port_lock); @@ -1495,12 +1484,12 @@ int xen_evtchn_send_op(struct evtchn_send *send) switch (p->type) { case EVTCHNSTAT_interdomain: - if (p->type_val & PORT_INFO_TYPEVAL_REMOTE_QEMU) { + if (p->u.interdomain.to_qemu) { /* * This is an event from the guest to qemu itself, which is * serving as the driver domain. */ - uint16_t be_port = p->type_val & ~PORT_INFO_TYPEVAL_REMOTE_QEMU; + uint16_t be_port = p->u.interdomain.port; struct xenevtchn_handle *xc = s->be_handles[be_port]; if (xc) { eventfd_write(xc->fd, 1); @@ -1510,7 +1499,7 @@ int xen_evtchn_send_op(struct evtchn_send *send) } } else { /* Loopback interdomain ports; just a complex IPI */ - set_port_pending(s, p->type_val); + set_port_pending(s, p->u.interdomain.port); } break; @@ -1552,8 +1541,7 @@ int xen_evtchn_set_port(uint16_t port) /* QEMU has no business sending to anything but these */ if (p->type == EVTCHNSTAT_virq || - (p->type == EVTCHNSTAT_interdomain && - (p->type_val & PORT_INFO_TYPEVAL_REMOTE_QEMU))) { + (p->type == EVTCHNSTAT_interdomain && p->u.interdomain.to_qemu)) { set_port_pending(s, port); ret = 0; } @@ -2063,7 +2051,7 @@ int xen_be_evtchn_bind_interdomain(struct xenevtchn_handle *xc, uint32_t domid, switch (gp->type) { case EVTCHNSTAT_interdomain: /* Allow rebinding after migration, preserve port # if possible */ - be_port = gp->type_val & ~PORT_INFO_TYPEVAL_REMOTE_QEMU; + be_port = gp->u.interdomain.port; assert(be_port != 0); if (!s->be_handles[be_port]) { s->be_handles[be_port] = xc; @@ -2084,7 +2072,8 @@ int xen_be_evtchn_bind_interdomain(struct xenevtchn_handle *xc, uint32_t domid, } gp->type = EVTCHNSTAT_interdomain; - gp->type_val = be_port | PORT_INFO_TYPEVAL_REMOTE_QEMU; + gp->u.interdomain.to_qemu = 1; + gp->u.interdomain.port = be_port; xc->guest_port = guest_port; if (kvm_xen_has_cap(EVTCHN_SEND)) { assign_kernel_eventfd(gp->type, guest_port, xc->fd); @@ -2129,7 +2118,7 @@ int xen_be_evtchn_unbind(struct xenevtchn_handle *xc, evtchn_port_t port) /* This should never *not* be true */ if (gp->type == EVTCHNSTAT_interdomain) { gp->type = EVTCHNSTAT_unbound; - gp->type_val = PORT_INFO_TYPEVAL_REMOTE_QEMU; + gp->u.interdomain.port = 0; } if (kvm_xen_has_cap(EVTCHN_SEND)) { @@ -2283,11 +2272,11 @@ EvtchnInfoList *qmp_xen_event_list(Error **errp) info->type = p->type; if (p->type == EVTCHNSTAT_interdomain) { - info->remote_domain = g_strdup((p->type_val & PORT_INFO_TYPEVAL_REMOTE_QEMU) ? + info->remote_domain = g_strdup(p->u.interdomain.to_qemu ? "qemu" : "loopback"); - info->target = p->type_val & PORT_INFO_TYPEVAL_REMOTE_PORT_MASK; + info->target = p->u.interdomain.port; } else { - info->target = p->type_val; + info->target = p->u.val; /* pirq# or virq# */ } info->vcpu = p->vcpu; info->pending = test_bit(i, pending); -- 2.40.1