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* [PATCH] powerpc: fix 32-bit KVM-PR lockup and panic with MacOS guest
@ 2019-02-08 14:33 Mark Cave-Ayland
  2019-02-08 14:45 ` Christophe Leroy
  2019-02-22  9:47 ` Michael Ellerman
  0 siblings, 2 replies; 11+ messages in thread
From: Mark Cave-Ayland @ 2019-02-08 14:33 UTC (permalink / raw)
  To: benh, paulus, mpe, npiggin, christophe.leroy, linuxppc-dev,
	linux-kernel, kvm-ppc

Commit 8792468da5e1 "powerpc: Add the ability to save FPU without giving it up"
unexpectedly removed the MSR_FE0 and MSR_FE1 bits from the bitmask used to
update the MSR of the previous thread in __giveup_fpu() causing a KVM-PR MacOS
guest to lockup and panic the kernel.

Reinstate these bits to the MSR bitmask to enable MacOS guests to run under
32-bit KVM-PR once again without issue.

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
---
 arch/powerpc/kernel/process.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index ce393df243aa..71bad4b6f80d 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -176,7 +176,7 @@ static void __giveup_fpu(struct task_struct *tsk)
 
 	save_fpu(tsk);
 	msr = tsk->thread.regs->msr;
-	msr &= ~MSR_FP;
+	msr &= ~(MSR_FP|MSR_FE0|MSR_FE1);
 #ifdef CONFIG_VSX
 	if (cpu_has_feature(CPU_FTR_VSX))
 		msr &= ~MSR_VSX;
-- 
2.11.0


^ permalink raw reply	[flat|nested] 11+ messages in thread

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Thread overview: 11+ messages (download: mbox.gz / follow: Atom feed)
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2019-02-08 14:33 [PATCH] powerpc: fix 32-bit KVM-PR lockup and panic with MacOS guest Mark Cave-Ayland
2019-02-08 14:45 ` Christophe Leroy
2019-02-08 14:51   ` Mark Cave-Ayland
2019-02-11  0:30     ` Benjamin Herrenschmidt
2019-02-11 21:39       ` Mark Cave-Ayland
2019-02-19  4:55         ` Michael Ellerman
2019-02-19  8:15           ` Mark Cave-Ayland
2019-02-19  4:20     ` Michael Ellerman
2019-02-19  7:55       ` Mark Cave-Ayland
2019-02-20 12:41         ` Michael Ellerman
2019-02-22  9:47 ` Michael Ellerman

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