Re: [PATCH v2 1/2] KVM: s390: fix ESSA addressing exception injection in migration mode

[sashiko-bot@kernel.org]

> __do_essa() treated any negative return from dat_perform_essa() as the
> normal "no CBRL entry appended" case and returned 0, so a page-table
> walk failure silently dropped the addressing exception.
> 
> Return -PGM_ADDRESSING on a walk failure and inject the program
> interrupt in __do_essa() for the -PGM_ADDRESSING return value.
> 
> DAT_WALK_ANY is required in the dat_entry_walk() call so that a GFN
> backed by a large page (segment or region entry) does not return an
> error: the walk stops early but succeeds, leaving ptep as NULL, which is
> already handled by the existing "set exception state, return -1" path.
> Without DAT_WALK_ANY such addresses would fall through to the new error
> path and incorrectly inject PGM_ADDRESSING.
> 
> Fixes: e38c884df921 ("KVM: s390: Switch to new gmap")
> Reported-by: Christian Borntraeger <borntraeger@linux.ibm.com>
> Suggested-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
> Acked-by: Christian Borntraeger <borntraeger@linux.ibm.com>
> Signed-off-by: Gautam Gala <ggala@linux.ibm.com>

Sashiko has reviewed this patch and found no issues. It looks great!

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