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Blame SOURCES/kvm-ppc-Deassert-the-external-interrupt-pin-in-KVM-on-re.patch

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From 22fc9bd7e7ae0b72c6f6e483eb66cf996f519766 Mon Sep 17 00:00:00 2001
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From: David Gibson <dgibson@redhat.com>
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Date: Tue, 21 Jan 2020 05:16:11 +0000
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Subject: [PATCH 01/15] ppc: Deassert the external interrupt pin in KVM on
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 reset
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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RH-Author: David Gibson <dgibson@redhat.com>
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Message-id: <20200121051613.388295-2-dgibson@redhat.com>
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Patchwork-id: 93429
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O-Subject: [RHEL-AV-8.2 qemu-kvm PATCH 1/3] ppc: Deassert the external interrupt pin in KVM on reset
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Bugzilla: 1776638
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RH-Acked-by: Philippe Mathieu-Daudé <philmd@redhat.com>
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RH-Acked-by: Laurent Vivier <lvivier@redhat.com>
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RH-Acked-by: Thomas Huth <thuth@redhat.com>
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From: Greg Kurz <groug@kaod.org>
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When a CPU is reset, QEMU makes sure no interrupt is pending by clearing
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CPUPPCstate::pending_interrupts in ppc_cpu_reset(). In the case of a
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complete machine emulation, eg. a sPAPR machine, an external interrupt
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request could still be pending in KVM though, eg. an IPI. It will be
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eventually presented to the guest, which is supposed to acknowledge it at
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the interrupt controller. If the interrupt controller is emulated in QEMU,
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either XICS or XIVE, ppc_set_irq() won't deassert the external interrupt
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pin in KVM since it isn't pending anymore for QEMU. When the vCPU re-enters
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the guest, the interrupt request is still pending and the vCPU will try
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again to acknowledge it. This causes an infinite loop and eventually hangs
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the guest.
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The code has been broken since the beginning. The issue wasn't hit before
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because accel=kvm,kernel-irqchip=off is an awkward setup that never got
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used until recently with the LC92x IBM systems (aka, Boston).
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Add a ppc_irq_reset() function to do the necessary cleanup, ie. deassert
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the IRQ pins of the CPU in QEMU and most importantly the external interrupt
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pin for this vCPU in KVM.
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Reported-by: Satheesh Rajendran <sathnaga@linux.vnet.ibm.com>
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Signed-off-by: Greg Kurz <groug@kaod.org>
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Message-Id: <157548861740.3650476.16879693165328764758.stgit@bahia.lan>
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Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
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(cherry picked from commit 401774387aeb37f2ada9bb18f7c7e307b21a3e93)
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Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1776638
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Signed-off-by: David Gibson <dgibson@redhat.com>
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Signed-off-by: Danilo C. L. de Paula <ddepaula@redhat.com>
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---
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 hw/ppc/ppc.c                    | 8 ++++++++
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 include/hw/ppc/ppc.h            | 2 ++
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 target/ppc/translate_init.inc.c | 1 +
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 3 files changed, 11 insertions(+)
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diff --git a/hw/ppc/ppc.c b/hw/ppc/ppc.c
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index 52a18eb..d554b64 100644
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--- a/hw/ppc/ppc.c
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+++ b/hw/ppc/ppc.c
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@@ -1510,3 +1510,11 @@ PowerPCCPU *ppc_get_vcpu_by_pir(int pir)
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     return NULL;
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 }
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+
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+void ppc_irq_reset(PowerPCCPU *cpu)
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+{
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+    CPUPPCState *env = &cpu->env;
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+
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+    env->irq_input_state = 0;
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+    kvmppc_set_interrupt(cpu, PPC_INTERRUPT_EXT, 0);
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+}
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diff --git a/include/hw/ppc/ppc.h b/include/hw/ppc/ppc.h
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index 4bdcb8b..5dd7531 100644
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--- a/include/hw/ppc/ppc.h
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+++ b/include/hw/ppc/ppc.h
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@@ -76,6 +76,7 @@ static inline void ppc970_irq_init(PowerPCCPU *cpu) {}
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 static inline void ppcPOWER7_irq_init(PowerPCCPU *cpu) {}
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 static inline void ppcPOWER9_irq_init(PowerPCCPU *cpu) {}
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 static inline void ppce500_irq_init(PowerPCCPU *cpu) {}
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+static inline void ppc_irq_reset(PowerPCCPU *cpu) {}
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 #else
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 void ppc40x_irq_init(PowerPCCPU *cpu);
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 void ppce500_irq_init(PowerPCCPU *cpu);
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@@ -83,6 +84,7 @@ void ppc6xx_irq_init(PowerPCCPU *cpu);
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 void ppc970_irq_init(PowerPCCPU *cpu);
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 void ppcPOWER7_irq_init(PowerPCCPU *cpu);
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 void ppcPOWER9_irq_init(PowerPCCPU *cpu);
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+void ppc_irq_reset(PowerPCCPU *cpu);
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 #endif
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 /* PPC machines for OpenBIOS */
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diff --git a/target/ppc/translate_init.inc.c b/target/ppc/translate_init.inc.c
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index ba726de..64a8380 100644
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--- a/target/ppc/translate_init.inc.c
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+++ b/target/ppc/translate_init.inc.c
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@@ -10461,6 +10461,7 @@ static void ppc_cpu_reset(CPUState *s)
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     env->pending_interrupts = 0;
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     s->exception_index = POWERPC_EXCP_NONE;
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     env->error_code = 0;
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+    ppc_irq_reset(cpu);
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     /* tininess for underflow is detected before rounding */
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     set_float_detect_tininess(float_tininess_before_rounding,
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-- 
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1.8.3.1
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