diff options
author | Benjamin Herrenschmidt <benh@kernel.crashing.org> | 2014-03-29 08:38:39 +1100 |
---|---|---|
committer | Eli Qiao <taget@linux.vnet.ibm.com> | 2014-03-31 11:16:42 +0800 |
commit | 4d2c729771c7758335700a7c244314d8a50fa4cd (patch) | |
tree | 3902f30190d164f86d111446508cab601f7036de | |
parent | 2fadb5567f4bd6baefe229b3894e006a8a03bca7 (diff) | |
download | powerkvm-4d2c729771c7758335700a7c244314d8a50fa4cd.tar.gz |
powerpc/ppc64: Gracefully handle early interrupts
If we take an interrupt such as a trap caused by a BUG_ON before the
MMU has been setup, the interrupt handlers try to enable virutal mode
and cause a recursive crash, making the original problem very hard
to debug.
This fixes it by adjusting the "kernel_msr" value in the PACA so that
it only has MSR_IR and MSR_DR (translation for instruction and data)
set after the MMU has been initialized for the processor.
We may still not have a console yet but at least we don't get into
a recursive fault (and early debug console or memory dump via JTAG
of the kernel buffer *will* give us the proper error).
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
-rw-r--r-- | arch/powerpc/kernel/paca.c | 3 | ||||
-rw-r--r-- | arch/powerpc/kernel/setup_64.c | 15 |
2 files changed, 17 insertions, 1 deletions
diff --git a/arch/powerpc/kernel/paca.c b/arch/powerpc/kernel/paca.c index f8f24685f10ac2..fac935fabc1b16 100644 --- a/arch/powerpc/kernel/paca.c +++ b/arch/powerpc/kernel/paca.c @@ -136,7 +136,8 @@ void __init initialise_paca(struct paca_struct *new_paca, int cpu) new_paca->paca_index = cpu; new_paca->kernel_toc = kernel_toc; new_paca->kernelbase = (unsigned long) _stext; - new_paca->kernel_msr = MSR_KERNEL; + /* Only set MSR:IR/DR when MMU is initialized */ + new_paca->kernel_msr = MSR_KERNEL & ~(MSR_IR | MSR_DR); new_paca->hw_cpu_id = 0xffff; new_paca->kexec_state = KEXEC_STATE_NONE; new_paca->__current = &init_task; diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c index a06edf67b4ce64..63741bf57d0091 100644 --- a/arch/powerpc/kernel/setup_64.c +++ b/arch/powerpc/kernel/setup_64.c @@ -229,6 +229,14 @@ void __init early_setup(unsigned long dt_ptr) /* Initialize the hash table or TLB handling */ early_init_mmu(); + /* + * At this point, we can let interrupts switch to virtual mode + * (the MMU has been setup), so adjust the MSR in the PACA to + * have IR and DR set. + */ + get_paca()->kernel_msr = MSR_KERNEL; + + /* Reserve large chunks of memory for use by CMA for KVM */ kvm_cma_reserve(); /* @@ -249,6 +257,13 @@ void early_setup_secondary(void) /* Initialize the hash table or TLB handling */ early_init_mmu_secondary(); + + /* + * At this point, we can let interrupts switch to virtual mode + * (the MMU has been setup), so adjust the MSR in the PACA to + * have IR and DR set. + */ + get_paca()->kernel_msr = MSR_KERNEL; } #endif /* CONFIG_SMP */ |