Commit ada68a66 authored by Mahesh Salgaonkar's avatar Mahesh Salgaonkar Committed by Michael Ellerman
Browse files

powerpc/64s: Move HMI IRQ stat from percpu variable to paca. 

With the proposed change in percpu bootmem allocator to use page
mapping [1], the percpu first chunk memory area can come from vmalloc
ranges. This makes the HMI (Hypervisor Maintenance Interrupt) handler
crash the kernel whenever percpu variable is accessed in real mode.
This patch fixes this issue by moving the HMI IRQ stat inside paca for
safe access in realmode.

[1] https://lore.kernel.org/linuxppc-dev/20200608070904.387440-1-aneesh.kumar@linux.ibm.com/



Suggested-by: default avatarAneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: default avatarMahesh Salgaonkar <mahesh@linux.ibm.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/159290806973.3642154.5244613424529764050.stgit@jupiter
parent d3c61954

arch/powerpc/include/asm/hardirq.h

+0 −1
Original line number Diff line number Diff line
@@ -13,7 +13,6 @@ typedef struct { 
	unsigned int pmu_irqs;

	unsigned int mce_exceptions;

	unsigned int spurious_irqs;

	unsigned int hmi_exceptions;

	unsigned int sreset_irqs;

#ifdef CONFIG_PPC_WATCHDOG

	unsigned int soft_nmi_irqs;

arch/powerpc/include/asm/paca.h

+1 −0
Original line number Diff line number Diff line
@@ -225,6 +225,7 @@ struct paca_struct { 
	u16 in_mce;

	u8 hmi_event_available;		/* HMI event is available */

	u8 hmi_p9_special_emu;		/* HMI P9 special emulation */

	u32 hmi_irqs;			/* HMI irq stat */

#endif

	u8 ftrace_enabled;		/* Hard disable ftrace */

arch/powerpc/kernel/irq.c

+6 −3
Original line number Diff line number Diff line
@@ -621,13 +621,14 @@ int arch_show_interrupts(struct seq_file *p, int prec) 
		seq_printf(p, "%10u ", per_cpu(irq_stat, j).mce_exceptions);

	seq_printf(p, "  Machine check exceptions\n");



#ifdef CONFIG_PPC_BOOK3S_64

	if (cpu_has_feature(CPU_FTR_HVMODE)) {

		seq_printf(p, "%*s: ", prec, "HMI");

		for_each_online_cpu(j)

			seq_printf(p, "%10u ",

					per_cpu(irq_stat, j).hmi_exceptions);

			seq_printf(p, "%10u ", paca_ptrs[j]->hmi_irqs);

		seq_printf(p, "  Hypervisor Maintenance Interrupts\n");

	}

#endif



	seq_printf(p, "%*s: ", prec, "NMI");

	for_each_online_cpu(j)
@@ -665,7 +666,9 @@ u64 arch_irq_stat_cpu(unsigned int cpu) 
	sum += per_cpu(irq_stat, cpu).mce_exceptions;

	sum += per_cpu(irq_stat, cpu).spurious_irqs;

	sum += per_cpu(irq_stat, cpu).timer_irqs_others;

	sum += per_cpu(irq_stat, cpu).hmi_exceptions;

#ifdef CONFIG_PPC_BOOK3S_64

	sum += paca_ptrs[cpu]->hmi_irqs;

#endif

	sum += per_cpu(irq_stat, cpu).sreset_irqs;

#ifdef CONFIG_PPC_WATCHDOG

	sum += per_cpu(irq_stat, cpu).soft_nmi_irqs;

arch/powerpc/kernel/mce.c

+1 −1
Original line number Diff line number Diff line
@@ -727,7 +727,7 @@ long hmi_exception_realmode(struct pt_regs *regs) 
{	

	int ret;



	__this_cpu_inc(irq_stat.hmi_exceptions);

	local_paca->hmi_irqs++;



	ret = hmi_handle_debugtrig(regs);

	if (ret >= 0)

arch/powerpc/kvm/book3s_hv_ras.c

+1 −1
Original line number Diff line number Diff line
@@ -244,7 +244,7 @@ long kvmppc_realmode_hmi_handler(void) 
{

	bool resync_req;



	__this_cpu_inc(irq_stat.hmi_exceptions);

	local_paca->hmi_irqs++;



	if (hmi_handle_debugtrig(NULL) >= 0)

		return 1;

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