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From: Paul Mackerras <paulus@samba.org>
To: Mahesh J Salgaonkar <mahesh@linux.vnet.ibm.com>
Cc: linuxppc-dev <linuxppc-dev@ozlabs.org>,
	Jeremy Kerr <jeremy.kerr@au1.ibm.com>,
	Anton Blanchard <anton@samba.org>
Subject: Re: [RFC PATCH 7/9] powerpc: Decode and save machine check event.
Date: Thu, 8 Aug 2013 15:14:22 +1000	[thread overview]
Message-ID: <20130808051422.GE12112@iris.ozlabs.ibm.com> (raw)
In-Reply-To: <20130807093913.5389.80206.stgit@mars.in.ibm.com>

On Wed, Aug 07, 2013 at 03:09:13PM +0530, Mahesh J Salgaonkar wrote:
> From: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
> 
> Now that we handle machine check in linux, the MCE decoding should also
> take place in linux host. This info is crucial to log before we go down
> in case we can not handle the machine check errors. This patch decodes
> and populates a machine check event which contain high level meaning full
> MCE information.

A couple of things worry me about this patch:

First, there is the fact that we can only do get_mce_event() once for
a given machine check.  You call it in kvmppc_realmode_mc_power7(),
which is fine, but if it is not something we recognize and can handle
we will proceed to exit the guest and jump to machine_check_fwnmi,
which will then proceed to machine_check_common() and then
opal_machine_check(), where you have added another call to
get_mce_event(), which will probably underflow your little per-cpu
stack of machine check events.

Secondly, we shouldn't call save_mce_event() if we're not in
hypervisor mode, since per-cpu variables are not in general accessible
in real mode when running under a hypervisor with a limited real-mode
area (RMA).

Paul.

  parent reply	other threads:[~2013-08-08  5:14 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-08-07  9:37 [RFC PATCH 0/9] Machine check handling in linux host Mahesh J Salgaonkar
2013-08-07  9:38 ` [RFC PATCH 1/9] powerpc: Split the common exception prolog logic into two section Mahesh J Salgaonkar
2013-08-08  4:10   ` Anshuman Khandual
2013-08-08  4:16     ` Benjamin Herrenschmidt
2013-08-07  9:38 ` [RFC PATCH 2/9] powerpc: handle machine check in Linux host Mahesh J Salgaonkar
2013-08-08  4:51   ` Paul Mackerras
2013-08-08 13:19     ` Mahesh Jagannath Salgaonkar
2013-08-08 13:33       ` Benjamin Herrenschmidt
2013-08-08  5:01   ` Anshuman Khandual
2013-08-07  9:38 ` [RFC PATCH 3/9] powerpc: Introduce a early machine check hook in cpu_spec Mahesh J Salgaonkar
2013-08-07  9:38 ` [RFC PATCH 4/9] powerpc: Add flush_tlb operation " Mahesh J Salgaonkar
2013-08-07  9:38 ` [RFC PATCH 5/9] powerpc: Flush SLB/TLBs if we get SLB/TLB machine check errors on power7 Mahesh J Salgaonkar
2013-08-08  4:58   ` Paul Mackerras
2013-08-07  9:39 ` [RFC PATCH 6/9] powerpc: Flush SLB/TLBs if we get SLB/TLB machine check errors on power8 Mahesh J Salgaonkar
2013-08-07  9:39 ` [RFC PATCH 7/9] powerpc: Decode and save machine check event Mahesh J Salgaonkar
2013-08-07 18:41   ` Scott Wood
2013-08-08  3:40     ` Mahesh Jagannath Salgaonkar
2013-08-08  5:14   ` Paul Mackerras [this message]
2013-08-08 13:19     ` Mahesh Jagannath Salgaonkar
2013-08-08 13:33       ` Benjamin Herrenschmidt
2013-08-07  9:39 ` [RFC PATCH 8/9] powerpc/powernv: Remove machine check handling in OPAL Mahesh J Salgaonkar
2013-08-07  9:39 ` [RFC PATCH 9/9] powerpc/powernv: Machine check exception handling Mahesh J Salgaonkar

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