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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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d6a4f70909
On PowerNV platforms, when a CPU is offline, we put it into nap mode. It's possible that the CPU wakes up from nap mode while it is still offline due to a stray IPI. A misdirected device interrupt could also potentially cause it to wake up. In that circumstance, we need to clear the interrupt so that the CPU can go back to nap mode. In the past the clearing of the interrupt was accomplished by briefly enabling interrupts and allowing the normal interrupt handling code (do_IRQ() etc.) to handle the interrupt. This has the problem that this code calls irq_enter() and irq_exit(), which call functions such as account_system_vtime() which use RCU internally. Use of RCU is not permitted on offline CPUs and will trigger errors if RCU checking is enabled. To avoid calling into any generic code which might use RCU, we adopt a different method of clearing interrupts on offline CPUs. Since we are on the PowerNV platform, we know that the system interrupt controller is a XICS being driven directly (i.e. not via hcalls) by the kernel. Hence this adds a new icp_native_flush_interrupt() function to the native-mode XICS driver and arranges to call that when an offline CPU is woken from nap. This new function reads the interrupt from the XICS. If it is an IPI, it clears the IPI; if it is a device interrupt, it prints a warning and disables the source. Then it does the end-of-interrupt processing for the interrupt. The other thing that briefly enabling interrupts did was to check and clear the irq_happened flag in this CPU's PACA. Therefore, after flushing the interrupt from the XICS, we also clear all bits except the PACA_IRQ_HARD_DIS (interrupts are hard disabled) bit from the irq_happened flag. The PACA_IRQ_HARD_DIS flag is set by power7_nap() and is left set to indicate that interrupts are hard disabled. This means we then have to ignore that flag in power7_nap(), which is reasonable since it doesn't indicate that any interrupt event needs servicing. Signed-off-by: Paul Mackerras <paulus@samba.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
164 lines
4.0 KiB
C
164 lines
4.0 KiB
C
/*
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* Common definitions accross all variants of ICP and ICS interrupt
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* controllers.
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*/
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#ifndef _XICS_H
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#define _XICS_H
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#include <linux/interrupt.h>
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#define XICS_IPI 2
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#define XICS_IRQ_SPURIOUS 0
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/* Want a priority other than 0. Various HW issues require this. */
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#define DEFAULT_PRIORITY 5
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/*
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* Mark IPIs as higher priority so we can take them inside interrupts
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* FIXME: still true now?
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*/
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#define IPI_PRIORITY 4
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/* The least favored priority */
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#define LOWEST_PRIORITY 0xFF
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/* The number of priorities defined above */
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#define MAX_NUM_PRIORITIES 3
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/* Native ICP */
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#ifdef CONFIG_PPC_ICP_NATIVE
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extern int icp_native_init(void);
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extern void icp_native_flush_interrupt(void);
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#else
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static inline int icp_native_init(void) { return -ENODEV; }
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#endif
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/* PAPR ICP */
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#ifdef CONFIG_PPC_ICP_HV
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extern int icp_hv_init(void);
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#else
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static inline int icp_hv_init(void) { return -ENODEV; }
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#endif
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/* ICP ops */
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struct icp_ops {
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unsigned int (*get_irq)(void);
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void (*eoi)(struct irq_data *d);
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void (*set_priority)(unsigned char prio);
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void (*teardown_cpu)(void);
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void (*flush_ipi)(void);
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#ifdef CONFIG_SMP
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void (*cause_ipi)(int cpu, unsigned long data);
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irq_handler_t ipi_action;
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#endif
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};
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extern const struct icp_ops *icp_ops;
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/* Native ICS */
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extern int ics_native_init(void);
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/* RTAS ICS */
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#ifdef CONFIG_PPC_ICS_RTAS
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extern int ics_rtas_init(void);
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#else
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static inline int ics_rtas_init(void) { return -ENODEV; }
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#endif
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/* HAL ICS */
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#ifdef CONFIG_PPC_POWERNV
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extern int ics_opal_init(void);
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#else
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static inline int ics_opal_init(void) { return -ENODEV; }
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#endif
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/* ICS instance, hooked up to chip_data of an irq */
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struct ics {
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struct list_head link;
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int (*map)(struct ics *ics, unsigned int virq);
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void (*mask_unknown)(struct ics *ics, unsigned long vec);
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long (*get_server)(struct ics *ics, unsigned long vec);
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int (*host_match)(struct ics *ics, struct device_node *node);
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char data[];
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};
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/* Commons */
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extern unsigned int xics_default_server;
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extern unsigned int xics_default_distrib_server;
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extern unsigned int xics_interrupt_server_size;
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extern struct irq_domain *xics_host;
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struct xics_cppr {
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unsigned char stack[MAX_NUM_PRIORITIES];
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int index;
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};
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DECLARE_PER_CPU(struct xics_cppr, xics_cppr);
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static inline void xics_push_cppr(unsigned int vec)
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{
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struct xics_cppr *os_cppr = &__get_cpu_var(xics_cppr);
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if (WARN_ON(os_cppr->index >= MAX_NUM_PRIORITIES - 1))
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return;
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if (vec == XICS_IPI)
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os_cppr->stack[++os_cppr->index] = IPI_PRIORITY;
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else
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os_cppr->stack[++os_cppr->index] = DEFAULT_PRIORITY;
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}
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static inline unsigned char xics_pop_cppr(void)
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{
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struct xics_cppr *os_cppr = &__get_cpu_var(xics_cppr);
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if (WARN_ON(os_cppr->index < 1))
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return LOWEST_PRIORITY;
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return os_cppr->stack[--os_cppr->index];
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}
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static inline void xics_set_base_cppr(unsigned char cppr)
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{
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struct xics_cppr *os_cppr = &__get_cpu_var(xics_cppr);
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/* we only really want to set the priority when there's
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* just one cppr value on the stack
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*/
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WARN_ON(os_cppr->index != 0);
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os_cppr->stack[0] = cppr;
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}
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static inline unsigned char xics_cppr_top(void)
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{
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struct xics_cppr *os_cppr = &__get_cpu_var(xics_cppr);
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return os_cppr->stack[os_cppr->index];
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}
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DECLARE_PER_CPU_SHARED_ALIGNED(unsigned long, xics_ipi_message);
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extern void xics_init(void);
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extern void xics_setup_cpu(void);
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extern void xics_update_irq_servers(void);
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extern void xics_set_cpu_giq(unsigned int gserver, unsigned int join);
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extern void xics_mask_unknown_vec(unsigned int vec);
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extern irqreturn_t xics_ipi_dispatch(int cpu);
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extern int xics_smp_probe(void);
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extern void xics_register_ics(struct ics *ics);
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extern void xics_teardown_cpu(void);
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extern void xics_kexec_teardown_cpu(int secondary);
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extern void xics_migrate_irqs_away(void);
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extern void icp_native_eoi(struct irq_data *d);
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#ifdef CONFIG_SMP
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extern int xics_get_irq_server(unsigned int virq, const struct cpumask *cpumask,
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unsigned int strict_check);
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#else
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#define xics_get_irq_server(virq, cpumask, strict_check) (xics_default_server)
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#endif
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#endif /* _XICS_H */
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