Quoting David Gibson (2016-10-13 23:56:43)
> On Wed, Oct 12, 2016 at 06:13:56PM -0500, Michael Roth wrote:
> > Hotplug events were previously delivered using an EPOW interrupt
> > and were queued by linux guests into a circular buffer. For traditional
> > EPOW events like shutdown/resets, this isn't an issue, but for hotplug
> > events there are cases where this buffer can be exhausted, resulting
> > in the loss of hotplug events, resets, etc.
> >
> > Newer-style hotplug event are delivered using a dedicated event source.
> > We enable this in supported guests by adding standard an additional
> > event source in the guest device-tree via /event-sources, and, if
> > the guest advertises support for the newer-style hotplug events,
> > using the corresponding interrupt to signal the available of
> > hotplug/unplug events.
> >
> > Signed-off-by: Michael Roth <mdr...@linux.vnet.ibm.com>
>
> So.. are you saying that as well as allowing new event types, the new
> special hotplug event souce effectively allows for a bigger queue?
>
> Does that mean that we didn't even necessarily need the base+length
> unplug events, because we could now have sent the many single-LMB
> unplug requests that were necessary? Or does it not increase the
> effective queue enough for that?
I assume there are still some internal limits, but the events
are now processed using a workqueue which should provide a bit more
headroom than the RTAS event buffer used for EPOW events. Maybe
John (on cc:) can provide more insight into what the actual limits
In either case, the possibility for huge memory hotplug/unplug
situations still warrant the use of count+index I think, and since
support for the new event delivery mechanism is negotiated using the
same option bit as count+index, there's not really any reason not to
use it when we can. For situations where we can't (CPU/PCI), it
might give us a bit of breathing room there as well.
>
> > ---
> > hw/ppc/spapr.c | 10 ++--
> > hw/ppc/spapr_events.c | 148
> > ++++++++++++++++++++++++++++++++++++++-----------
> > include/hw/ppc/spapr.h | 3 +-
> > 3 files changed, 120 insertions(+), 41 deletions(-)
> >
> > diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> > index d80a6fa..2037222 100644
> > --- a/hw/ppc/spapr.c
> > +++ b/hw/ppc/spapr.c
> > @@ -275,8 +275,7 @@ static void *spapr_create_fdt_skel(hwaddr initrd_base,
> > hwaddr initrd_size,
> > hwaddr kernel_size,
> > bool little_endian,
> > - const char *kernel_cmdline,
> > - uint32_t epow_irq)
> > + const char *kernel_cmdline)
> > {
> > void *fdt;
> > uint32_t start_prop = cpu_to_be32(initrd_base);
> > @@ -437,7 +436,7 @@ static void *spapr_create_fdt_skel(hwaddr initrd_base,
> > _FDT((fdt_end_node(fdt)));
> >
> > /* event-sources */
> > - spapr_events_fdt_skel(fdt, epow_irq);
> > + spapr_events_fdt_skel(fdt);
> >
> > /* /hypervisor node */
> > if (kvm_enabled()) {
> > @@ -1944,7 +1943,7 @@ static void ppc_spapr_init(MachineState *machine)
> > }
> > g_free(filename);
> >
> > - /* Set up EPOW events infrastructure */
> > + /* Set up RTAS event infrastructure */
> > spapr_events_init(spapr);
> >
> > /* Set up the RTC RTAS interfaces */
> > @@ -2076,8 +2075,7 @@ static void ppc_spapr_init(MachineState *machine)
> > /* Prepare the device tree */
> > spapr->fdt_skel = spapr_create_fdt_skel(initrd_base, initrd_size,
> > kernel_size, kernel_le,
> > - kernel_cmdline,
> > - spapr->check_exception_irq);
> > + kernel_cmdline);
> > assert(spapr->fdt_skel != NULL);
> >
> > /* used by RTAS */
> > diff --git a/hw/ppc/spapr_events.c b/hw/ppc/spapr_events.c
> > index 4c7b6ae..f8bbec6 100644
> > --- a/hw/ppc/spapr_events.c
> > +++ b/hw/ppc/spapr_events.c
> > @@ -40,6 +40,7 @@
> > #include "hw/ppc/spapr_drc.h"
> > #include "qemu/help_option.h"
> > #include "qemu/bcd.h"
> > +#include "hw/ppc/spapr_ovec.h"
> > #include <libfdt.h>
> >
> > struct rtas_error_log {
> > @@ -206,28 +207,104 @@ struct hp_log_full {
> > struct rtas_event_log_v6_hp hp;
> > } QEMU_PACKED;
> >
> > -#define EVENT_MASK_INTERNAL_ERRORS 0x80000000
> > -#define EVENT_MASK_EPOW 0x40000000
> > -#define EVENT_MASK_HOTPLUG 0x10000000
> > -#define EVENT_MASK_IO 0x08000000
> > +typedef enum EventClassIndex {
> > + EVENT_CLASS_INTERNAL_ERRORS = 0,
> > + EVENT_CLASS_EPOW = 1,
> > + EVENT_CLASS_RESERVED = 2,
> > + EVENT_CLASS_HOT_PLUG = 3,
> > + EVENT_CLASS_IO = 4,
> > + EVENT_CLASS_MAX
> > +} EventClassIndex;
> > +
> > +#define EVENT_CLASS_MASK(index) (1 << (31 - index))
> > +
> > +typedef struct EventSource {
> > + const char *name;
> > + int irq;
> > + uint32_t mask;
> > + bool enabled;
> > +} EventSource;
> > +
> > +static EventSource event_source[EVENT_CLASS_MAX] = {
> > + [EVENT_CLASS_INTERNAL_ERRORS] = { .name = "internal-errors", },
> > + [EVENT_CLASS_EPOW] = { .name = "epow-events", },
> > + [EVENT_CLASS_HOT_PLUG] = { .name = "hot-plug-events", },
> > + [EVENT_CLASS_IO] = { .name = "ibm,io-events", },
> > +};
> > +
> > +static void rtas_event_source_register(EventClassIndex index, int irq)
> > +{
> > + /* we only support 1 irq per event class at the moment */
> > + g_assert(!event_source[index].enabled);
> > + event_source[index].irq = irq;
> > + event_source[index].mask = EVENT_CLASS_MASK(index);
> > + event_source[index].enabled = true;
> > +}
>
> I really don't like adding a mutable global table. This should
> probably be under the sPAPRMachineState.
I think I started off going that route. Not sure what steered me in this
direction, but will take another look at that approach.
>
> > -void spapr_events_fdt_skel(void *fdt, uint32_t check_exception_irq)
> > +void spapr_events_fdt_skel(void *fdt)
> > {
> > - uint32_t irq_ranges[] = {cpu_to_be32(check_exception_irq),
> > cpu_to_be32(1)};
> > - uint32_t interrupts[] = {cpu_to_be32(check_exception_irq), 0};
> > + uint32_t irq_ranges[EVENT_CLASS_MAX * 2];
> > + int i, count = 0;
> >
> > _FDT((fdt_begin_node(fdt, "event-sources")));
> >
> > + for (i = 0, count = 0; i < EVENT_CLASS_MAX; i++) {
> > + /* TODO: what does 0 entail? */
>
> It's just part of the interrupt specifier format expected by the
> event-sources binding. It's not really important.
>
> > + uint32_t interrupts[] = { cpu_to_be32(event_source[i].irq), 0 };
> > +
> > + if (!event_source[i].enabled) {
> > + continue;
> > + }
> > +
> > + _FDT((fdt_begin_node(fdt, event_source[i].name)));
> > + _FDT((fdt_property(fdt, "interrupts", interrupts,
> > sizeof(interrupts))));
> > + _FDT((fdt_end_node(fdt)));
> > +
> > + irq_ranges[count++] = interrupts[0];
> > + irq_ranges[count++] = cpu_to_be32(1);
> > + }
> > +
> > + /* TODO: confirm the count is the last expected element */
> > + irq_ranges[count] = cpu_to_be32(count);
> > + count++;
> > +
> > _FDT((fdt_property(fdt, "interrupt-controller", NULL, 0)));
> > _FDT((fdt_property_cell(fdt, "#interrupt-cells", 2)));
> > _FDT((fdt_property(fdt, "interrupt-ranges",
> > - irq_ranges, sizeof(irq_ranges))));
> > + irq_ranges, count * sizeof(uint32_t))));
> >
> > - _FDT((fdt_begin_node(fdt, "epow-events")));
> > - _FDT((fdt_property(fdt, "interrupts", interrupts,
> > sizeof(interrupts))));
> > _FDT((fdt_end_node(fdt)));
> > +}
> >
> > - _FDT((fdt_end_node(fdt)));
> > +static const EventSource *rtas_event_log_to_source(int log_type)
> > +{
> > + const EventSource *source;
> > +
> > + switch (log_type) {
> > + case RTAS_LOG_TYPE_HOTPLUG:
> > + source = &event_source[EVENT_CLASS_HOT_PLUG];
> > + if (event_source[EVENT_CLASS_HOT_PLUG].enabled) {
> > + break;
> > + }
>
> This should probably be using the flag you already have in the
> MachineState, rather than a global.
>
> > + /* fall back to epow for legacy hotplug interrupt source */
> > + case RTAS_LOG_TYPE_EPOW:
> > + source = &event_source[EVENT_CLASS_EPOW];
> > + break;
> > + default:
> > + source = NULL;
> > + }
> > +
> > + return source;
> > +}
> > +
> > +static int rtas_event_log_to_irq(int log_type)
> > +{
> > + const EventSource *source = rtas_event_log_to_source(log_type);
> > +
> > + g_assert(source);
> > + g_assert(source->enabled);
> > +
> > + return source->irq;
> > }
> >
> > static void rtas_event_log_queue(int log_type, void *data, bool exception)
> > @@ -248,19 +325,14 @@ static sPAPREventLogEntry
> > *rtas_event_log_dequeue(uint32_t event_mask,
> > sPAPRMachineState *spapr = SPAPR_MACHINE(qdev_get_machine());
> > sPAPREventLogEntry *entry = NULL;
> >
> > - /* we only queue EPOW events atm. */
> > - if ((event_mask & EVENT_MASK_EPOW) == 0) {
> > - return NULL;
> > - }
> > -
> > QTAILQ_FOREACH(entry, &spapr->pending_events, next) {
> > + const EventSource *source =
> > rtas_event_log_to_source(entry->log_type);
> > +
> > if (entry->exception != exception) {
> > continue;
> > }
> >
> > - /* EPOW and hotplug events are surfaced in the same manner */
> > - if (entry->log_type == RTAS_LOG_TYPE_EPOW ||
> > - entry->log_type == RTAS_LOG_TYPE_HOTPLUG) {
> > + if (source->mask & event_mask) {
> > break;
> > }
> > }
> > @@ -277,19 +349,14 @@ static bool rtas_event_log_contains(uint32_t
> > event_mask, bool exception)
> > sPAPRMachineState *spapr = SPAPR_MACHINE(qdev_get_machine());
> > sPAPREventLogEntry *entry = NULL;
> >
> > - /* we only queue EPOW events atm. */
> > - if ((event_mask & EVENT_MASK_EPOW) == 0) {
> > - return false;
> > - }
> > -
> > QTAILQ_FOREACH(entry, &spapr->pending_events, next) {
> > + const EventSource *source =
> > rtas_event_log_to_source(entry->log_type);
> > +
> > if (entry->exception != exception) {
> > continue;
> > }
> >
> > - /* EPOW and hotplug events are surfaced in the same manner */
> > - if (entry->log_type == RTAS_LOG_TYPE_EPOW ||
> > - entry->log_type == RTAS_LOG_TYPE_HOTPLUG) {
> > + if (source->mask & event_mask) {
> > return true;
> > }
> > }
> > @@ -377,7 +444,8 @@ static void spapr_powerdown_req(Notifier *n, void
> > *opaque)
> >
> > rtas_event_log_queue(RTAS_LOG_TYPE_EPOW, new_epow, true);
> >
> > - qemu_irq_pulse(xics_get_qirq(spapr->xics, spapr->check_exception_irq));
> > + qemu_irq_pulse(xics_get_qirq(spapr->xics,
> > +
> > rtas_event_log_to_irq(RTAS_LOG_TYPE_EPOW)));
> > }
> >
> > static void spapr_hotplug_set_signalled(uint32_t drc_index)
> > @@ -459,7 +527,8 @@ static void spapr_hotplug_req_event(uint8_t hp_id,
> > uint8_t hp_action,
> >
> > rtas_event_log_queue(RTAS_LOG_TYPE_HOTPLUG, new_hp, true);
> >
> > - qemu_irq_pulse(xics_get_qirq(spapr->xics, spapr->check_exception_irq));
> > + qemu_irq_pulse(xics_get_qirq(spapr->xics,
> > +
> > rtas_event_log_to_irq(RTAS_LOG_TYPE_HOTPLUG)));
> > }
> >
> > void spapr_hotplug_req_add_by_index(sPAPRDRConnector *drc)
> > @@ -505,6 +574,7 @@ static void check_exception(PowerPCCPU *cpu,
> > sPAPRMachineState *spapr,
> > uint64_t xinfo;
> > sPAPREventLogEntry *event;
> > struct rtas_error_log *hdr;
> > + int i;
> >
> > if ((nargs < 6) || (nargs > 7) || nret != 1) {
> > rtas_st(rets, 0, RTAS_OUT_PARAM_ERROR);
> > @@ -541,8 +611,11 @@ static void check_exception(PowerPCCPU *cpu,
> > sPAPRMachineState *spapr,
> > * do the latter here, since our code relies on edge-triggered
> > * interrupts.
> > */
> > - if (rtas_event_log_contains(mask, true)) {
> > - qemu_irq_pulse(xics_get_qirq(spapr->xics,
> > spapr->check_exception_irq));
> > + for (i = 0; i < EVENT_CLASS_MAX; i++) {
> > + if (rtas_event_log_contains(EVENT_CLASS_MASK(i), true)) {
> > + g_assert(event_source[i].enabled);
> > + qemu_irq_pulse(xics_get_qirq(spapr->xics,
> > event_source[i].irq));
> > + }
> > }
> >
> > return;
> > @@ -594,8 +667,17 @@ out_no_events:
> > void spapr_events_init(sPAPRMachineState *spapr)
> > {
> > QTAILQ_INIT(&spapr->pending_events);
> > - spapr->check_exception_irq = xics_spapr_alloc(spapr->xics, 0, 0, false,
> > - &error_fatal);
> > +
> > + rtas_event_source_register(EVENT_CLASS_EPOW,
> > + xics_spapr_alloc(spapr->xics, 0, 0, false,
> > + &error_fatal));
> > +
> > + if (spapr->use_hotplug_event_source) {
> > + rtas_event_source_register(EVENT_CLASS_HOT_PLUG,
> > + xics_spapr_alloc(spapr->xics, 0, 0,
> > false,
> > + &error_fatal));
> > + }
> > +
> > spapr->epow_notifier.notify = spapr_powerdown_req;
> > qemu_register_powerdown_notifier(&spapr->epow_notifier);
> > spapr_rtas_register(RTAS_CHECK_EXCEPTION, "check-exception",
> > diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
> > index d1a4a14..2295ac6 100644
> > --- a/include/hw/ppc/spapr.h
> > +++ b/include/hw/ppc/spapr.h
> > @@ -71,7 +71,6 @@ struct sPAPRMachineState {
> > sPAPROptionVector *ov5_cas;
> > bool cas_reboot;
> >
> > - uint32_t check_exception_irq;
> > Notifier epow_notifier;
> > QTAILQ_HEAD(, sPAPREventLogEntry) pending_events;
> > bool use_hotplug_event_source;
> > @@ -579,7 +578,7 @@ struct sPAPREventLogEntry {
> > };
> >
> > void spapr_events_init(sPAPRMachineState *sm);
> > -void spapr_events_fdt_skel(void *fdt, uint32_t epow_irq);
> > +void spapr_events_fdt_skel(void *fdt);
> > int spapr_h_cas_compose_response(sPAPRMachineState *sm,
> > target_ulong addr, target_ulong size,
> > bool cpu_update,
>
> --
> David Gibson | I'll have my music baroque, and my code
> david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
> | _way_ _around_!
> http://www.ozlabs.org/~dgibson
