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authorMichael Ellerman <mpe@ellerman.id.au>2018-10-17 23:39:41 +1100
committerMichael Ellerman <mpe@ellerman.id.au>2018-10-19 15:09:04 +1100
commitb4d16ab58c41ff0125822464bdff074cebd0fe47 (patch)
tree7db5b7b66ed3375723eb5647ada4f91b94f3fd5d /arch/powerpc/kernel/time.c
parent6ce7bff045f6a0eaa94c63617d73ad0bc66ce40c (diff)
downloadlinux-b4d16ab58c41ff0125822464bdff074cebd0fe47.tar.gz
powerpc/time: Fix clockevent_decrementer initalisation for PR KVM
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>
Diffstat (limited to 'arch/powerpc/kernel/time.c')
-rw-r--r--arch/powerpc/kernel/time.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c
index 40868f3ee113..68e8f963d108 100644
--- a/arch/powerpc/kernel/time.c
+++ b/arch/powerpc/kernel/time.c
@@ -989,6 +989,10 @@ 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)