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[POWERPC] Avoid hypervisor statistics calculation in real mode

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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>
This commit is contained in:
Mohan Kumar M 2007-03-21 11:21:32 +05:30 committed by Paul Mackerras
parent f144e7c727
commit b4aea36b79
4 changed files with 65 additions and 1 deletions
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34
arch/powerpc/platforms/pseries/hvCall.S
View file

@ -123,6 +123,40 @@ _GLOBAL(plpar_hcall)
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

2
arch/powerpc/platforms/pseries/lpar.c
View file

@ -378,7 +378,7 @@ static void pSeries_lpar_hptab_clear(void)
/* 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);
}
/*

16
arch/powerpc/platforms/pseries/plpar_wrappers.h
View file

@ -78,6 +78,22 @@ static inline long plpar_pte_remove(unsigned long flags, unsigned long ptex,
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)
{

14
include/asm-powerpc/hvcall.h
View file

@ -236,6 +236,20 @@ long plpar_hcall_norets(unsigned long opcode, ...);
#define PLPAR_HCALL_BUFSIZE 4
long plpar_hcall(unsigned long opcode, unsigned long *retbuf, ...);
/**
* plpar_hcall_raw: - Make a hypervisor call without calculating hcall stats
* @opcode: The hypervisor call to make.
* @retbuf: Buffer to store up to 4 return arguments in.
*
* This call supports up to 6 arguments and 4 return arguments. Use
* PLPAR_HCALL_BUFSIZE to size the return argument buffer.
*
* Used when phyp interface needs to be called in real mode. Similar to
* plpar_hcall, but plpar_hcall_raw works in real mode and does not
* calculate hypervisor call statistics.
*/
long plpar_hcall_raw(unsigned long opcode, unsigned long *retbuf, ...);
/**
* plpar_hcall9: - Make a pseries hypervisor call with up to 9 return arguments
* @opcode: The hypervisor call to make.