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powerpc: Don't try to set LPCR unless we're in hypervisor mode

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Commit 8f619b5429 ("powerpc/ppc64: Do not turn AIL (reloc-on
interrupts) too early") added code to set the AIL bit in the LPCR
without checking whether the kernel is running in hypervisor mode.  The
result is that when the kernel is running as a guest (i.e., under
PowerKVM or PowerVM), the processor takes a privileged instruction
interrupt at that point, causing a panic.  The visible result is that
the kernel hangs after printing "returning from prom_init".

This fixes it by checking for hypervisor mode being available before
setting LPCR.  If we are not in hypervisor mode, we enable relocation-on
interrupts later in pSeries_setup_arch using the H_SET_MODE hcall.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Paul Mackerras 2014-04-11 16:43:35 +10:00 committed by Linus Torvalds
parent d7e8af1afe
commit 18aa0da33e
1 changed files with 2 additions and 1 deletions
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arch/powerpc/kernel/setup_64.c
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@ -201,7 +201,8 @@ static void cpu_ready_for_interrupts(void)
get_paca()->kernel_msr = MSR_KERNEL;
/* Enable AIL if supported */
if (cpu_has_feature(CPU_FTR_ARCH_207S)) {
if (cpu_has_feature(CPU_FTR_HVMODE) &&
cpu_has_feature(CPU_FTR_ARCH_207S)) {
unsigned long lpcr = mfspr(SPRN_LPCR);
mtspr(SPRN_LPCR, lpcr | LPCR_AIL_3);
}