powerpc/64s: Fix compiler store ordering to SLB shadow area

Tue Jun 5 00:11:22 AEST 2018

On Wed, 2018-05-30 at 10:31:22 UTC, Nicholas Piggin wrote:
> The stores to update the SLB shadow area must be made as they appear
> in the C code, so that the hypervisor does not see an entry with
> mismatched vsid and esid. Use WRITE_ONCE for this.
> 
> GCC has been observed to elide the first store to esid in the update,
> which means that if the hypervisor interrupts the guest after storing
> to vsid, it could see an entry with old esid and new vsid, which may
> possibly result in memory corruption.
> 
> Signed-off-by: Nicholas Piggin <npiggin at gmail.com>

Applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/926bc2f100c24d4842b3064b5af44a

cheers