From c1703e85a7b20ffcefd5360e2542460737ecc15c Mon Sep 17 00:00:00 2001
From: Anton Blanchard <anton@samba.org>
Date: Sun, 3 Jun 2012 19:42:13 +0000
Subject: [PATCH] powerpc/pseries: Disable interrupts around IOMMU percpu data
accesses
tce_buildmulti_pSeriesLP uses a per cpu page to communicate with the
hypervisor. We currently rely on the IOMMU table spinlock but
subsequent patches will be removing that so disable interrupts
around all accesses of tce_page.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---
arch/powerpc/platforms/pseries/iommu.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c
index d5d1dd58ca742f..07c09cbbfb19fd 100644
--- a/arch/powerpc/platforms/pseries/iommu.c
+++ b/arch/powerpc/platforms/pseries/iommu.c
@@ -192,12 +192,15 @@ static int tce_buildmulti_pSeriesLP(struct iommu_table *tbl, long tcenum,
long l, limit;
long tcenum_start = tcenum, npages_start = npages;
int ret = 0;
+ unsigned long flags;
if (npages == 1) {
return tce_build_pSeriesLP(tbl, tcenum, npages, uaddr,
direction, attrs);
}
+ local_irq_save(flags); /* to protect tcep and the page behind it */
+
tcep = __get_cpu_var(tce_page);
/* This is safe to do since interrupts are off when we're called
@@ -207,6 +210,7 @@ static int tce_buildmulti_pSeriesLP(struct iommu_table *tbl, long tcenum,
tcep = (u64 *)__get_free_page(GFP_ATOMIC);
/* If allocation fails, fall back to the loop implementation */
if (!tcep) {
+ local_irq_restore(flags);
return tce_build_pSeriesLP(tbl, tcenum, npages, uaddr,
direction, attrs);
}
@@ -240,6 +244,8 @@ static int tce_buildmulti_pSeriesLP(struct iommu_table *tbl, long tcenum,
tcenum += limit;
} while (npages > 0 && !rc);
+ local_irq_restore(flags);
+
if (unlikely(rc == H_NOT_ENOUGH_RESOURCES)) {
ret = (int)rc;
tce_freemulti_pSeriesLP(tbl, tcenum_start,
--
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