From f2aeed761d2dad14920fa08c977dc45564886d9b Mon Sep 17 00:00:00 2001 From: David Gibson Date: Fri, 3 Jan 2020 01:15:12 +0000 Subject: [PATCH 1/5] spapr: Don't trigger a CAS reboot for XICS/XIVE mode changeover MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit RH-Author: David Gibson Message-id: <20200103011512.49129-2-dgibson@redhat.com> Patchwork-id: 93261 O-Subject: [RHEL-AV-4.2 qemu-kvm PATCH 1/1] spapr: Don't trigger a CAS reboot for XICS/XIVE mode changeover Bugzilla: 1733893 RH-Acked-by: Laurent Vivier RH-Acked-by: Thomas Huth RH-Acked-by: Philippe Mathieu-Daudé From: David Gibson PAPR allows the interrupt controller used on a POWER9 machine (XICS or XIVE) to be selected by the guest operating system, by using the ibm,client-architecture-support (CAS) feature negotiation call. Currently, if the guest selects an interrupt controller different from the one selected at initial boot, this causes the system to be reset with the new model and the boot starts again. This means we run through the SLOF boot process twice, as well as any other bootloader (e.g. grub) in use before the OS calls CAS. This can be confusing and/or inconvenient for users. Thanks to two fairly recent changes, we no longer need this reboot. 1) we now completely regenerate the device tree when CAS is called (meaning we don't need special case updates for all the device tree changes caused by the interrupt controller mode change), 2) we now have explicit code paths to activate and deactivate the different interrupt controllers, rather than just implicitly calling those at machine reset time. We can therefore eliminate the reboot for changing irq mode, simply by putting a call to spapr_irq_update_active_intc() before we call spapr_h_cas_compose_response() (which gives the updated device tree to the guest firmware and OS). Signed-off-by: David Gibson Reviewed-by: Cedric Le Goater Reviewed-by: Greg Kurz (cherry picked from commit 8deb8019d696c75e6ecaee7545026b62aba2f1bb) Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1733893 Signed-off-by: David Gibson Signed-off-by: Danilo C. L. de Paula --- hw/ppc/spapr_hcall.c | 33 +++++++++++++-------------------- 1 file changed, 13 insertions(+), 20 deletions(-) diff --git a/hw/ppc/spapr_hcall.c b/hw/ppc/spapr_hcall.c index 140f05c..05a7ca2 100644 --- a/hw/ppc/spapr_hcall.c +++ b/hw/ppc/spapr_hcall.c @@ -1767,21 +1767,10 @@ static target_ulong h_client_architecture_support(PowerPCCPU *cpu, } spapr->cas_pre_isa3_guest = !spapr_ovec_test(ov1_guest, OV1_PPC_3_00); spapr_ovec_cleanup(ov1_guest); - if (!spapr->cas_reboot) { - /* If spapr_machine_reset() did not set up a HPT but one is necessary - * (because the guest isn't going to use radix) then set it up here. */ - if ((spapr->patb_entry & PATE1_GR) && !guest_radix) { - /* legacy hash or new hash: */ - spapr_setup_hpt_and_vrma(spapr); - } - spapr->cas_reboot = - (spapr_h_cas_compose_response(spapr, args[1], args[2], - ov5_updates) != 0); - } /* - * Ensure the guest asks for an interrupt mode we support; otherwise - * terminate the boot. + * Ensure the guest asks for an interrupt mode we support; + * otherwise terminate the boot. */ if (guest_xive) { if (!spapr->irq->xive) { @@ -1797,14 +1786,18 @@ static target_ulong h_client_architecture_support(PowerPCCPU *cpu, } } - /* - * Generate a machine reset when we have an update of the - * interrupt mode. Only required when the machine supports both - * modes. - */ + spapr_irq_update_active_intc(spapr); + if (!spapr->cas_reboot) { - spapr->cas_reboot = spapr_ovec_test(ov5_updates, OV5_XIVE_EXPLOIT) - && spapr->irq->xics && spapr->irq->xive; + /* If spapr_machine_reset() did not set up a HPT but one is necessary + * (because the guest isn't going to use radix) then set it up here. */ + if ((spapr->patb_entry & PATE1_GR) && !guest_radix) { + /* legacy hash or new hash: */ + spapr_setup_hpt_and_vrma(spapr); + } + spapr->cas_reboot = + (spapr_h_cas_compose_response(spapr, args[1], args[2], + ov5_updates) != 0); } spapr_ovec_cleanup(ov5_updates); -- 1.8.3.1