linux-kernel - Re: powernv: Restore SPRs correctly upon wake up from hypervisor state loss

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Message-Id: <3sY25S6bdKz9sdn@ozlabs.org>
Date:   Tue, 13 Sep 2016 08:09:00 +1000 (AEST)
From:   Michael Ellerman <patch-notifications@...erman.id.au>
To:     "Gautham R. Shenoy" <ego@...ux.vnet.ibm.com>,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Cc:     "Shreyas B. Prabhu" <shreyasbp@...il.com>,
        "Gautham R. Shenoy" <ego@...ux.vnet.ibm.com>,
        Michael Neuling <michael.neuling@....ibm.com>
Subject: Re: powernv: Restore SPRs correctly upon wake up from hypervisor state loss

On Wed, 2016-07-09 at 05:16:30 UTC, "Gautham R. Shenoy" wrote:
> From: "Gautham R. Shenoy" <ego@...ux.vnet.ibm.com>
> 
> 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")
> Signed-off-by: Gautham R. Shenoy <ego@...ux.vnet.ibm.com>
> Reviewed-by: Shreyas B. Prabhu <shreyasbp@...il.com>

Applied to powerpc fixes, thanks.

https://git.kernel.org/powerpc/c/bd00a240dc52e28706fbbe3ace

cheers