[POWERPC] Avoid hypervisor statistics calculation in real mode
kexec invokes plpar_hcall hypervisor call in real mode. plpar_hcall
refers to per cpu variables for accounting hypervisor statistics.
These variables may not be in the RMO region, so accesses to them
in real mode may result in a data storage exception.
This fixes this problem by using a new plpar_hcall_raw function which
does not update the hypervisor call statistics. Thanks to Anton for
suggesting this idea.
Signed-off-by: Mohan Kumar M <mohan@in.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/arch/powerpc/platforms/pseries/hvCall.S b/arch/powerpc/platforms/pseries/hvCall.S
index 5c7e387..1501b0a9 100644
--- a/arch/powerpc/platforms/pseries/hvCall.S
+++ b/arch/powerpc/platforms/pseries/hvCall.S
@@ -123,6 +123,40 @@
blr /* return r3 = status */
+/*
+ * plpar_hcall_raw can be called in real mode. kexec/kdump need some
+ * hypervisor calls to be executed in real mode. So plpar_hcall_raw
+ * does not access the per cpu hypervisor call statistics variables,
+ * since these variables may not be present in the RMO region.
+ */
+_GLOBAL(plpar_hcall_raw)
+ HMT_MEDIUM
+
+ mfcr r0
+ stw r0,8(r1)
+
+ std r4,STK_PARM(r4)(r1) /* Save ret buffer */
+
+ mr r4,r5
+ mr r5,r6
+ mr r6,r7
+ mr r7,r8
+ mr r8,r9
+ mr r9,r10
+
+ HVSC /* invoke the hypervisor */
+
+ ld r12,STK_PARM(r4)(r1)
+ std r4, 0(r12)
+ std r5, 8(r12)
+ std r6, 16(r12)
+ std r7, 24(r12)
+
+ lwz r0,8(r1)
+ mtcrf 0xff,r0
+
+ blr /* return r3 = status */
+
_GLOBAL(plpar_hcall9)
HMT_MEDIUM
diff --git a/arch/powerpc/platforms/pseries/lpar.c b/arch/powerpc/platforms/pseries/lpar.c
index 7496005..843ee96 100644
--- a/arch/powerpc/platforms/pseries/lpar.c
+++ b/arch/powerpc/platforms/pseries/lpar.c
@@ -378,7 +378,7 @@
/* TODO: Use bulk call */
for (i = 0; i < hpte_count; i++)
- plpar_pte_remove(0, i, 0, &dummy1, &dummy2);
+ plpar_pte_remove_raw(0, i, 0, &dummy1, &dummy2);
}
/*
diff --git a/arch/powerpc/platforms/pseries/plpar_wrappers.h b/arch/powerpc/platforms/pseries/plpar_wrappers.h
index 3eb7b29..2e4d10c 100644
--- a/arch/powerpc/platforms/pseries/plpar_wrappers.h
+++ b/arch/powerpc/platforms/pseries/plpar_wrappers.h
@@ -78,6 +78,22 @@
return rc;
}
+/* plpar_pte_remove_raw can be called in real mode. It calls plpar_hcall_raw */
+static inline long plpar_pte_remove_raw(unsigned long flags, unsigned long ptex,
+ unsigned long avpn, unsigned long *old_pteh_ret,
+ unsigned long *old_ptel_ret)
+{
+ long rc;
+ unsigned long retbuf[PLPAR_HCALL_BUFSIZE];
+
+ rc = plpar_hcall_raw(H_REMOVE, retbuf, flags, ptex, avpn);
+
+ *old_pteh_ret = retbuf[0];
+ *old_ptel_ret = retbuf[1];
+
+ return rc;
+}
+
static inline long plpar_pte_read(unsigned long flags, unsigned long ptex,
unsigned long *old_pteh_ret, unsigned long *old_ptel_ret)
{