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powerpc/time: Fix clockevent_decrementer initalisation for PR KVM

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[ Upstream commit b4d16ab58c41ff0125822464bdff074cebd0fe47 ]

In the recent commit 8b78fdb045de ("powerpc/time: Use
clockevents_register_device(), fixing an issue with large
decrementer") we changed the way we initialise the decrementer
clockevent(s).

We no longer initialise the mult & shift values of
decrementer_clockevent itself.

This has the effect of breaking PR KVM, because it uses those values
in kvmppc_emulate_dec(). The symptom is guest kernels spin forever
mid-way through boot.

For now fix it by assigning back to decrementer_clockevent the mult
and shift values.

Fixes: 8b78fdb045de ("powerpc/time: Use clockevents_register_device(), fixing an issue with large decrementer")
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Michael Ellerman
2018-10-17 23:39:41 +11:00
committed by Greg Kroah-Hartman
parent ff36ace6c1
commit e2a37708cf
1 changed files with 4 additions and 0 deletions
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4
arch/powerpc/kernel/time.c
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@ -988,6 +988,10 @@ static void register_decrementer_clockevent(int cpu)
printk_once(KERN_DEBUG "clockevent: %s mult[%x] shift[%d] cpu[%d]\n",
dec->name, dec->mult, dec->shift, cpu);
/* Set values for KVM, see kvm_emulate_dec() */
decrementer_clockevent.mult = dec->mult;
decrementer_clockevent.shift = dec->shift;
}
static void enable_large_decrementer(void)