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Re: [PATCH] spapr: Handle pending hot plug/unplug requests at CAS
From: |
David Gibson |
Subject: |
Re: [PATCH] spapr: Handle pending hot plug/unplug requests at CAS |
Date: |
Tue, 25 Feb 2020 11:55:54 +1100 |
On Mon, Feb 24, 2020 at 08:23:43PM +0100, Greg Kurz wrote:
> If a hot plug or unplug request is pending at CAS, we currently trigger
> a CAS reboot, which severely increases the guest boot time. This is
> because SLOF doesn't handle hot plug events and we had no way to fix
> the FDT that gets presented to the guest.
>
> We can do better thanks to recent changes in QEMU and SLOF:
>
> - we now return a full FDT to SLOF during CAS
>
> - SLOF was fixed to correctly detect any device that was either added or
> removed since boot time and to update its internal DT accordingly.
>
> The right solution is to process all pending hot plug/unplug requests
> during CAS: convert hot plugged devices to cold plugged devices and
> remove the hot unplugged ones, which is exactly what spapr_drc_reset()
> does. Also clear all hot plug events that are currently queued since
> they're no longer relevant.
>
> Note that SLOF cannot currently populate hot plugged PCI bridges or PHBs
> at CAS. Until this limitation is lifted, SLOF will reset the machine when
> this scenario occurs : this will allow the FDT to be fully processed when
> SLOF is started again (ie. the same effect as the CAS reboot that would
> occur anyway without this patch).
>
> Signed-off-by: Greg Kurz <address@hidden>
LGTM, applied to ppc-for-5.0.
> ---
> hw/ppc/spapr_events.c | 13 +++++++++++++
> hw/ppc/spapr_hcall.c | 11 +++++------
> include/hw/ppc/spapr.h | 1 +
> 3 files changed, 19 insertions(+), 6 deletions(-)
>
> diff --git a/hw/ppc/spapr_events.c b/hw/ppc/spapr_events.c
> index 8b32b7eea526..2afd1844e4d4 100644
> --- a/hw/ppc/spapr_events.c
> +++ b/hw/ppc/spapr_events.c
> @@ -983,6 +983,19 @@ void spapr_clear_pending_events(SpaprMachineState *spapr)
> }
> }
>
> +void spapr_clear_pending_hotplug_events(SpaprMachineState *spapr)
> +{
> + SpaprEventLogEntry *entry = NULL, *next_entry;
> +
> + QTAILQ_FOREACH_SAFE(entry, &spapr->pending_events, next, next_entry) {
> + if (spapr_event_log_entry_type(entry) == RTAS_LOG_TYPE_HOTPLUG) {
> + QTAILQ_REMOVE(&spapr->pending_events, entry, next);
> + g_free(entry->extended_log);
> + g_free(entry);
> + }
> + }
> +}
> +
> void spapr_events_init(SpaprMachineState *spapr)
> {
> int epow_irq = SPAPR_IRQ_EPOW;
> diff --git a/hw/ppc/spapr_hcall.c b/hw/ppc/spapr_hcall.c
> index 6db3dbde9c92..5992849c1664 100644
> --- a/hw/ppc/spapr_hcall.c
> +++ b/hw/ppc/spapr_hcall.c
> @@ -1640,7 +1640,7 @@ static uint32_t cas_check_pvr(SpaprMachineState *spapr,
> PowerPCCPU *cpu,
> return best_compat;
> }
>
> -static bool spapr_transient_dev_before_cas(void)
> +static void spapr_handle_transient_dev_before_cas(SpaprMachineState *spapr)
> {
> Object *drc_container;
> ObjectProperty *prop;
> @@ -1658,10 +1658,11 @@ static bool spapr_transient_dev_before_cas(void)
> prop->name, NULL));
>
> if (spapr_drc_transient(drc)) {
> - return true;
> + spapr_drc_reset(drc);
> }
> }
> - return false;
> +
> + spapr_clear_pending_hotplug_events(spapr);
> }
>
> static target_ulong h_client_architecture_support(PowerPCCPU *cpu,
> @@ -1834,9 +1835,7 @@ static target_ulong
> h_client_architecture_support(PowerPCCPU *cpu,
>
> spapr_irq_update_active_intc(spapr);
>
> - if (spapr_transient_dev_before_cas()) {
> - spapr->cas_reboot = true;
> - }
> + spapr_handle_transient_dev_before_cas(spapr);
>
> if (!spapr->cas_reboot) {
> void *fdt;
> diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
> index 09110961a589..a4216935a148 100644
> --- a/include/hw/ppc/spapr.h
> +++ b/include/hw/ppc/spapr.h
> @@ -824,6 +824,7 @@ int spapr_hpt_shift_for_ramsize(uint64_t ramsize);
> void spapr_reallocate_hpt(SpaprMachineState *spapr, int shift,
> Error **errp);
> void spapr_clear_pending_events(SpaprMachineState *spapr);
> +void spapr_clear_pending_hotplug_events(SpaprMachineState *spapr);
> int spapr_max_server_number(SpaprMachineState *spapr);
> void spapr_store_hpte(PowerPCCPU *cpu, hwaddr ptex,
> uint64_t pte0, uint64_t pte1);
>
--
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
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