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>
diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c
index d5d1dd5..07c09cb 100644
--- a/arch/powerpc/platforms/pseries/iommu.c
+++ b/arch/powerpc/platforms/pseries/iommu.c
@@ -192,12 +192,15 @@
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 @@
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 @@
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,