Re: [PATCH] powernv: Restore SPRs correctly upon wake up from hypervisor state loss

Hi Gautham,

Thanks for fixing this.

On Wed, Sep 7, 2016 at 1:16 AM, Gautham R. Shenoy
[off-list ref] wrote:

From: "Gautham R. Shenoy" <redacted>

pnv_wakeup_tb_loss function currently expects the cr4 to be "eq" if
the CPU is waking up from a complete hypervisor state loss. Hence, it
currently restores the SPR contents only if cr4 is "eq".

However, after the commit bcef83a00dc4 ("powerpc/powernv: Add platform
support for stop instruction"), on ISA_V300 CPUs, the function
pnv_restore_hyp_resource sets cr4 to contain the result of the
comparison between state the CPU has woken up and the first deepest
stop state before calling pnv_wakeup_tb_loss.

Thus if the CPU woke up from a state that is deeper than the first
deepest stop state, cr4 have "gt" set and hence, pnv_wakeup_tb_loss
will fail to restore the SPRs on waking up from such a state.

Fix the code in pnv_wakeup_tb_loss to restore the SPR states when cr4 is
"eq" or "gt".

Fixes: Commit bcef83a00dc4 ("powerpc/powernv: Add platform support for
stop instruction")

Cc: Vaidyanathan Srinivasan <redacted>
Cc: Michael Neuling <redacted>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Shreyas B. Prabhu <redacted>
Signed-off-by: Gautham R. Shenoy <redacted>
---

Reviewed-by: Shreyas B. Prabhu <redacted>


Thanks,
Shreyas