Re: [PATCH v14 4/7] target/ppc: Build rtas error log upon an MCE

[David Gibson]

On Wed, Sep 25, 2019 at 11:31:30AM +0530, Aravinda Prasad wrote:
> 
> 
> On Wednesday 25 September 2019 07:00 AM, David Gibson wrote:
> > On Wed, Sep 18, 2019 at 01:42:34PM +0530, Aravinda Prasad wrote:
> >> Upon a machine check exception (MCE) in a guest address space,
> >> KVM causes a guest exit to enable QEMU to build and pass the
> >> error to the guest in the PAPR defined rtas error log format.
> >>
> >> This patch builds the rtas error log, copies it to the rtas_addr
> >> and then invokes the guest registered machine check handler. The
> >> handler in the guest takes suitable action(s) depending on the type
> >> and criticality of the error. For example, if an error is
> >> unrecoverable memory corruption in an application inside the
> >> guest, then the guest kernel sends a SIGBUS to the application.
> >> For recoverable errors, the guest performs recovery actions and
> >> logs the error.
> >>
> >> Signed-off-by: Aravinda Prasad <address@hidden>
> >> ---
> >>  hw/ppc/spapr.c         |   13 +++
> >>  hw/ppc/spapr_events.c  |  222 
> >> ++++++++++++++++++++++++++++++++++++++++++++++++
> >>  hw/ppc/spapr_rtas.c    |   26 ++++++
> >>  include/hw/ppc/spapr.h |    6 +
> >>  target/ppc/kvm.c       |    4 +
> >>  5 files changed, 268 insertions(+), 3 deletions(-)
> >>
> >> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> >> index 76ed988..9f2e5d2 100644
> >> --- a/hw/ppc/spapr.c
> >> +++ b/hw/ppc/spapr.c
> >> @@ -2930,6 +2930,19 @@ static void spapr_machine_init(MachineState 
> >> *machine)
> >>          error_report("Could not get size of LPAR rtas '%s'", filename);
> >>          exit(1);
> >>      }
> >> +
> >> +    if (spapr_get_cap(spapr, SPAPR_CAP_FWNMI_MCE) == SPAPR_CAP_ON) {
> >> +        /*
> >> +         * Ensure that the rtas image size is less than 
> >> RTAS_ERROR_LOG_OFFSET
> >> +         * or else the rtas image will be overwritten with the rtas error 
> >> log
> >> +         * when a machine check exception is encountered.
> >> +         */
> >> +        g_assert(spapr->rtas_size < RTAS_ERROR_LOG_OFFSET);
> >> +
> >> +        /* Resize rtas blob to accommodate error log */
> >> +        spapr->rtas_size = RTAS_ERROR_LOG_MAX;
> >> +    }
> >> +
> > 
> > I've recently merged into ppc-for-4.2 the change to have SLOF supply
> > the RTAS blob, rather than qemu.  So this code will need to be updated
> > accordingly.
> 
> Sure. Will modify it to check if rtas_size is set to RTAS_ERROR_LOG_MAX
> instead of the assignment.

There is no rtas_size variable now.  You'll need to just trust that
SLOF has allocated enough room.

-- 
David Gibson                    | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au  | minimalist, thank you.  NOT _the_ _other_
                                | _way_ _around_!
http://www.ozlabs.org/~dgibson

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