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Re: [PATCH] powerpc: fix 32-bit KVM-PR lockup and panic with MacOS guest






Le 08/02/2019 à 15:33, Mark Cave-Ayland a écrit :
Commit 8792468da5e1 "powerpc: Add the ability to save FPU without giving it up"

Expected format for the above is:

Commit 123456789abc ("text")

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@xxxxxxxxxxxx>

Should include a Fixes: and a Cc to stable ?

Fixes: 8792468da5e1 ("powerpc: Add the ability to save FPU without giving it up")
Cc: stable@xxxxxxxxxxxxxxx

Christophe

---
  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;