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authorPaul Mackerras <paulus@samba.org>2011-12-05 19:47:26 +0000
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>2011-12-08 14:22:53 +1100
commit2fde6d20bb75b53f1ead383b4713f95d0d6d9f59 (patch)
tree7353b02df53c43b21e4f2bd42218fd89ad4769b3 /arch/powerpc/include
parentcba313da5c8ddbe6bba74c9f2b8f6d9e0bc0e723 (diff)
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powerpc: Provide a way for KVM to indicate that NV GPR values are lost
This fixes a problem where a CPU thread coming out of nap mode can think it has valid values in the nonvolatile GPRs (r14 - r31) as saved away in power7_idle, but in fact the values have been trashed because the thread was used for KVM in the mean time. The result is that the thread crashes because code that called power7_idle (e.g., pnv_smp_cpu_kill_self()) goes to use values in registers that have been trashed. The bit field in SRR1 that tells whether state was lost only reflects the most recent nap, which may not have been the nap instruction in power7_idle. So we need an extra PACA field to indicate that state has been lost even if SRR1 indicates that the most recent nap didn't lose state. We clear this field when saving the state in power7_idle, we set it to a non-zero value when we use the thread for KVM, and we test it in power7_wakeup_noloss. Signed-off-by: Paul Mackerras <paulus@samba.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Diffstat (limited to 'arch/powerpc/include')
-rw-r--r--arch/powerpc/include/asm/paca.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/powerpc/include/asm/paca.h b/arch/powerpc/include/asm/paca.h
index 17722c7..269c05a3 100644
--- a/arch/powerpc/include/asm/paca.h
+++ b/arch/powerpc/include/asm/paca.h
@@ -135,6 +135,7 @@ struct paca_struct {
u8 hard_enabled; /* set if irqs are enabled in MSR */
u8 io_sync; /* writel() needs spin_unlock sync */
u8 irq_work_pending; /* IRQ_WORK interrupt while soft-disable */
+ u8 nap_state_lost; /* NV GPR values lost in power7_idle */
#ifdef CONFIG_PPC_POWERNV
/* Pointer to OPAL machine check event structure set by the
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