Commit 9bf811da authored by Claudio Imbrenda's avatar Claudio Imbrenda Committed by Janosch Frank
Browse files

s390/mm: KVM: pv: when tearing down, try to destroy protected pages 



When ptep_get_and_clear_full is called for a mm teardown, we will now
attempt to destroy the secure pages. This will be faster than export.

In case it was not a teardown, or if for some reason the destroy page
UVC failed, we try with an export page, like before.

Signed-off-by: default avatarClaudio Imbrenda <imbrenda@linux.ibm.com>
Acked-by: default avatarJanosch Frank <frankja@linux.ibm.com>
Reviewed-by: default avatarNico Boehr <nrb@linux.ibm.com>
Link: https://lore.kernel.org/r/20220628135619.32410-11-imbrenda@linux.ibm.com


Message-Id: <20220628135619.32410-11-imbrenda@linux.ibm.com>
Signed-off-by: default avatarJanosch Frank <frankja@linux.ibm.com>
parent ca2fd060

arch/s390/include/asm/pgtable.h

+16 −3
Original line number Diff line number Diff line
@@ -1182,8 +1182,21 @@ static inline pte_t ptep_get_and_clear_full(struct mm_struct *mm, 
	} else {

		res = ptep_xchg_lazy(mm, addr, ptep, __pte(_PAGE_INVALID));

	}

	/* At this point the reference through the mapping is still present */

	if (mm_is_protected(mm) && pte_present(res))

	/* Nothing to do */

	if (!mm_is_protected(mm) || !pte_present(res))

		return res;

	/*

	 * At this point the reference through the mapping is still present.

	 * The notifier should have destroyed all protected vCPUs at this

	 * point, so the destroy should be successful.

	 */

	if (full && !uv_destroy_owned_page(pte_val(res) & PAGE_MASK))

		return res;

	/*

	 * If something went wrong and the page could not be destroyed, or

	 * if this is not a mm teardown, the slower export is used as

	 * fallback instead.

	 */

	uv_convert_owned_from_secure(pte_val(res) & PAGE_MASK);

	return res;

}