linux-kernel - [PATCH kernel v7 11/20] powerpc/powernv: Reference iommu

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Date:   Thu, 20 Dec 2018 19:23:41 +1100
From:   Alexey Kardashevskiy <aik@...abs.ru>
To:     linuxppc-dev@...ts.ozlabs.org
Cc:     Alexey Kardashevskiy <aik@...abs.ru>,
        David Gibson <david@...son.dropbear.id.au>,
        kvm-ppc@...r.kernel.org, kvm@...r.kernel.org,
        Alistair Popple <alistair@...ple.id.au>,
        Reza Arbab <arbab@...ux.ibm.com>,
        Sam Bobroff <sbobroff@...ux.ibm.com>,
        Piotr Jaroszynski <pjaroszynski@...dia.com>,
        Leonardo Augusto Guimarães Garcia 
        <lagarcia@...ibm.com>, Jose Ricardo Ziviani <joserz@...ux.ibm.com>,
        Daniel Henrique Barboza <danielhb413@...il.com>,
        Alex Williamson <alex.williamson@...hat.com>,
        Paul Mackerras <paulus@...abs.org>,
        linux-kernel@...r.kernel.org, Christoph Hellwig <hch@...radead.org>
Subject: [PATCH kernel v7 11/20] powerpc/powernv: Reference iommu_table while it is linked to a group

The iommu_table pointer stored in iommu_table_group may get stale
by accident, this adds referencing and removes a redundant comment
about this.

Signed-off-by: Alexey Kardashevskiy <aik@...abs.ru>
Reviewed-by: David Gibson <david@...son.dropbear.id.au>
---
 arch/powerpc/platforms/powernv/pci-ioda-tce.c | 3 ++-
 arch/powerpc/platforms/powernv/pci-ioda.c     | 4 ----
 2 files changed, 2 insertions(+), 5 deletions(-)

diff --git a/arch/powerpc/platforms/powernv/pci-ioda-tce.c b/arch/powerpc/platforms/powernv/pci-ioda-tce.c
index 7639b21..697449a 100644
--- a/arch/powerpc/platforms/powernv/pci-ioda-tce.c
+++ b/arch/powerpc/platforms/powernv/pci-ioda-tce.c
@@ -368,6 +368,7 @@ void pnv_pci_unlink_table_and_group(struct iommu_table *tbl,
 	found = false;
 	for (i = 0; i < IOMMU_TABLE_GROUP_MAX_TABLES; ++i) {
 		if (table_group->tables[i] == tbl) {
+			iommu_tce_table_put(tbl);
 			table_group->tables[i] = NULL;
 			found = true;
 			break;
@@ -393,7 +394,7 @@ long pnv_pci_link_table_and_group(int node, int num,
 	tgl->table_group = table_group;
 	list_add_rcu(&tgl->next, &tbl->it_group_list);
 
-	table_group->tables[num] = tbl;
+	table_group->tables[num] = iommu_tce_table_get(tbl);
 
 	return 0;
 }
diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c
index f6ab13d..a5879ab 100644
--- a/arch/powerpc/platforms/powernv/pci-ioda.c
+++ b/arch/powerpc/platforms/powernv/pci-ioda.c
@@ -2719,10 +2719,6 @@ static long pnv_pci_ioda2_npu_unset_window(
 
 static void pnv_ioda2_npu_take_ownership(struct iommu_table_group *table_group)
 {
-	/*
-	 * Detach NPU first as pnv_ioda2_take_ownership() will destroy
-	 * the iommu_table if 32bit DMA is enabled.
-	 */
 	pnv_npu_take_ownership(gpe_table_group_to_npe(table_group));
 	pnv_ioda2_take_ownership(table_group);
 }
-- 
2.17.1