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* [PATCH] Avoid hypervisor statistics calculation in real mode
@ 2007-03-20 13:35 Mohan Kumar M
  2007-03-20 22:37 ` [Fastboot] " Randy Dunlap
  0 siblings, 1 reply; 5+ messages in thread
From: Mohan Kumar M @ 2007-03-20 13:35 UTC (permalink / raw)
  To: linuxppc-dev, fastboot; +Cc: paulus, anton

kexec invokes plpar_hcall hypervisor call in real mode. plpar_hcall
refers per cpu variable for accounting hypervisor statistics. These
variables may not be present in the RMO region. So it results in
0x300 exception.

The following patch fixes this problem by using raw hypervisor call
which does not update the hypervisor call statistics. Thanks to Anton
for suggesting this idea.

Cc: Anton Blanchard <anton@samba.org>
Signed-off-by: Mohan Kumar M <mohan@in.ibm.com>
---
 arch/powerpc/platforms/pseries/hvCall.S         |   34 ++++++++++++++++++++++++
 arch/powerpc/platforms/pseries/lpar.c           |    2 -
 arch/powerpc/platforms/pseries/plpar_wrappers.h |   19 +++++++++++++
 include/asm-powerpc/hvcall.h                    |   15 ++++++++++
 4 files changed, 69 insertions(+), 1 deletion(-)

Index: linux-2.6.21-rc4/arch/powerpc/platforms/pseries/hvCall.S
===================================================================
--- linux-2.6.21-rc4.orig/arch/powerpc/platforms/pseries/hvCall.S
+++ linux-2.6.21-rc4/arch/powerpc/platforms/pseries/hvCall.S
@@ -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
 
Index: linux-2.6.21-rc4/arch/powerpc/platforms/pseries/lpar.c
===================================================================
--- linux-2.6.21-rc4.orig/arch/powerpc/platforms/pseries/lpar.c
+++ linux-2.6.21-rc4/arch/powerpc/platforms/pseries/lpar.c
@@ -378,7 +378,7 @@ static void pSeries_lpar_hptab_clear(voi
 
 	/* 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);
 }
 
 /*
Index: linux-2.6.21-rc4/arch/powerpc/platforms/pseries/plpar_wrappers.h
===================================================================
--- linux-2.6.21-rc4.orig/arch/powerpc/platforms/pseries/plpar_wrappers.h
+++ linux-2.6.21-rc4/arch/powerpc/platforms/pseries/plpar_wrappers.h
@@ -78,6 +78,25 @@ static inline long plpar_pte_remove(unsi
 	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)
 {
Index: linux-2.6.21-rc4/include/asm-powerpc/hvcall.h
===================================================================
--- linux-2.6.21-rc4.orig/include/asm-powerpc/hvcall.h
+++ linux-2.6.21-rc4/include/asm-powerpc/hvcall.h
@@ -237,6 +237,21 @@ long plpar_hcall_norets(unsigned long op
 long plpar_hcall(unsigned long opcode, unsigned long *retbuf, ...);
 
 /**
+ * plpar_hcall_raw: - Make a pseries hypervisor call, but don't calculate
+ * hypervisor call statistics.
+ * @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.
  * @retbuf: Buffer to store up to 9 return arguments in.

^ permalink raw reply	[flat|nested] 5+ messages in thread
* Re: [Fastboot] [PATCH] Avoid hypervisor statistics calculation in real mode
  2007-03-20 13:35 [PATCH] Avoid hypervisor statistics calculation in real mode Mohan Kumar M
@ 2007-03-20 22:37 ` Randy Dunlap
  2007-03-21  5:51   ` Mohan Kumar M
  0 siblings, 1 reply; 5+ messages in thread
From: Randy Dunlap @ 2007-03-20 22:37 UTC (permalink / raw)
  To: mohan; +Cc: linuxppc-dev, fastboot, anton, paulus

On Tue, 20 Mar 2007 19:05:47 +0530 Mohan Kumar M wrote:

> Cc: Anton Blanchard <anton@samba.org>
> Signed-off-by: Mohan Kumar M <mohan@in.ibm.com>
> ---
>  arch/powerpc/platforms/pseries/hvCall.S         |   34 ++++++++++++++++++++++++
>  arch/powerpc/platforms/pseries/lpar.c           |    2 -
>  arch/powerpc/platforms/pseries/plpar_wrappers.h |   19 +++++++++++++
>  include/asm-powerpc/hvcall.h                    |   15 ++++++++++
>  4 files changed, 69 insertions(+), 1 deletion(-)
> 
> Index: linux-2.6.21-rc4/arch/powerpc/platforms/pseries/hvCall.S
> ===================================================================
> --- linux-2.6.21-rc4.orig/arch/powerpc/platforms/pseries/hvCall.S
> +++ linux-2.6.21-rc4/arch/powerpc/platforms/pseries/hvCall.S
> @@ -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.
> + */

Hi,
Please use regular kernel long comment style (when not using
kernel-doc).  E.g.:

/*
 * foo
 * bar
 * this is a long comment (several lines)
 */

> +_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
>  

> Index: linux-2.6.21-rc4/include/asm-powerpc/hvcall.h
> ===================================================================
> --- linux-2.6.21-rc4.orig/include/asm-powerpc/hvcall.h
> +++ linux-2.6.21-rc4/include/asm-powerpc/hvcall.h
> @@ -237,6 +237,21 @@ long plpar_hcall_norets(unsigned long op
>  long plpar_hcall(unsigned long opcode, unsigned long *retbuf, ...);
>  
>  /**
> + * plpar_hcall_raw: - Make a pseries hypervisor call, but don't calculate
> + * hypervisor call statistics.

For kernel-doc, the first line must be:

 * function - short description (one line only)

More detailed description can follow the parameters (like you have
done below).

> + * @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.
>   * @retbuf: Buffer to store up to 9 return arguments in.


Thanks.
---
~Randy
*** Remember to use Documentation/SubmitChecklist when testing your code ***

^ permalink raw reply	[flat|nested] 5+ messages in thread
* Re: [Fastboot] [PATCH] Avoid hypervisor statistics calculation in real mode
  2007-03-20 22:37 ` [Fastboot] " Randy Dunlap
@ 2007-03-21  5:51   ` Mohan Kumar M
  2007-03-21 15:30     ` Randy Dunlap
  2007-03-23  6:18     ` Horms
  0 siblings, 2 replies; 5+ messages in thread
From: Mohan Kumar M @ 2007-03-21  5:51 UTC (permalink / raw)
  To: Randy Dunlap; +Cc: linuxppc-dev, fastboot, anton, paulus

Thanks Randy.

I updated the patch as per your suggestions.


kexec invokes plpar_hcall hypervisor call in real mode. plpar_hcall
refers per cpu variable for accounting hypervisor statistics. These
variables may not be present in the RMO region. So it results in
0x300 exception.

The following patch fixes this problem by using raw hypervisor call
which does not update the hypervisor call statistics. Thanks to Anton
for suggesting this idea.

Cc: Anton Blanchard <anton@samba.org>
Signed-off-by: Mohan Kumar M <mohan@in.ibm.com>
---
 arch/powerpc/platforms/pseries/hvCall.S         |   34 ++++++++++++++++++++++++
 arch/powerpc/platforms/pseries/lpar.c           |    2 -
 arch/powerpc/platforms/pseries/plpar_wrappers.h |   16 +++++++++++
 include/asm-powerpc/hvcall.h                    |   14 +++++++++
 4 files changed, 65 insertions(+), 1 deletion(-)

Index: linux-2.6.21-rc4/arch/powerpc/platforms/pseries/hvCall.S
===================================================================
--- linux-2.6.21-rc4.orig/arch/powerpc/platforms/pseries/hvCall.S
+++ linux-2.6.21-rc4/arch/powerpc/platforms/pseries/hvCall.S
@@ -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
 
Index: linux-2.6.21-rc4/arch/powerpc/platforms/pseries/lpar.c
===================================================================
--- linux-2.6.21-rc4.orig/arch/powerpc/platforms/pseries/lpar.c
+++ linux-2.6.21-rc4/arch/powerpc/platforms/pseries/lpar.c
@@ -378,7 +378,7 @@ static void pSeries_lpar_hptab_clear(voi
 
 	/* 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);
 }
 
 /*
Index: linux-2.6.21-rc4/arch/powerpc/platforms/pseries/plpar_wrappers.h
===================================================================
--- linux-2.6.21-rc4.orig/arch/powerpc/platforms/pseries/plpar_wrappers.h
+++ linux-2.6.21-rc4/arch/powerpc/platforms/pseries/plpar_wrappers.h
@@ -78,6 +78,22 @@ static inline long plpar_pte_remove(unsi
 	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)
 {
Index: linux-2.6.21-rc4/include/asm-powerpc/hvcall.h
===================================================================
--- linux-2.6.21-rc4.orig/include/asm-powerpc/hvcall.h
+++ linux-2.6.21-rc4/include/asm-powerpc/hvcall.h
@@ -237,6 +237,20 @@ long plpar_hcall_norets(unsigned long op
 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.
  * @retbuf: Buffer to store up to 9 return arguments in.

^ permalink raw reply	[flat|nested] 5+ messages in thread
* Re: [Fastboot] [PATCH] Avoid hypervisor statistics calculation in real mode
  2007-03-21  5:51   ` Mohan Kumar M
@ 2007-03-21 15:30     ` Randy Dunlap
  2007-03-23  6:18     ` Horms
  1 sibling, 0 replies; 5+ messages in thread
From: Randy Dunlap @ 2007-03-21 15:30 UTC (permalink / raw)
  To: mohan; +Cc: linuxppc-dev, fastboot, anton, paulus

On Wed, 21 Mar 2007 11:21:32 +0530 Mohan Kumar M wrote:

> Thanks Randy.
> 
> I updated the patch as per your suggestions.
> 

Thanks, looks fine to me.

> kexec invokes plpar_hcall hypervisor call in real mode. plpar_hcall
> refers per cpu variable for accounting hypervisor statistics. These
> variables may not be present in the RMO region. So it results in
> 0x300 exception.
> 
> The following patch fixes this problem by using raw hypervisor call
> which does not update the hypervisor call statistics. Thanks to Anton
> for suggesting this idea.
> 
> Cc: Anton Blanchard <anton@samba.org>
> Signed-off-by: Mohan Kumar M <mohan@in.ibm.com>
> ---
>  arch/powerpc/platforms/pseries/hvCall.S         |   34 ++++++++++++++++++++++++
>  arch/powerpc/platforms/pseries/lpar.c           |    2 -
>  arch/powerpc/platforms/pseries/plpar_wrappers.h |   16 +++++++++++
>  include/asm-powerpc/hvcall.h                    |   14 +++++++++
>  4 files changed, 65 insertions(+), 1 deletion(-)
> 
> Index: linux-2.6.21-rc4/arch/powerpc/platforms/pseries/hvCall.S
> ===================================================================
> --- linux-2.6.21-rc4.orig/arch/powerpc/platforms/pseries/hvCall.S
> +++ linux-2.6.21-rc4/arch/powerpc/platforms/pseries/hvCall.S
> @@ -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
>  
> Index: linux-2.6.21-rc4/arch/powerpc/platforms/pseries/lpar.c
> ===================================================================
> --- linux-2.6.21-rc4.orig/arch/powerpc/platforms/pseries/lpar.c
> +++ linux-2.6.21-rc4/arch/powerpc/platforms/pseries/lpar.c
> @@ -378,7 +378,7 @@ static void pSeries_lpar_hptab_clear(voi
>  
>  	/* 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);
>  }
>  
>  /*
> Index: linux-2.6.21-rc4/arch/powerpc/platforms/pseries/plpar_wrappers.h
> ===================================================================
> --- linux-2.6.21-rc4.orig/arch/powerpc/platforms/pseries/plpar_wrappers.h
> +++ linux-2.6.21-rc4/arch/powerpc/platforms/pseries/plpar_wrappers.h
> @@ -78,6 +78,22 @@ static inline long plpar_pte_remove(unsi
>  	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)
>  {
> Index: linux-2.6.21-rc4/include/asm-powerpc/hvcall.h
> ===================================================================
> --- linux-2.6.21-rc4.orig/include/asm-powerpc/hvcall.h
> +++ linux-2.6.21-rc4/include/asm-powerpc/hvcall.h
> @@ -237,6 +237,20 @@ long plpar_hcall_norets(unsigned long op
>  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.
>   * @retbuf: Buffer to store up to 9 return arguments in.
> _______________________________________________
> fastboot mailing list
> fastboot@lists.linux-foundation.org
> https://lists.linux-foundation.org/mailman/listinfo/fastboot
> 


---
~Randy
*** Remember to use Documentation/SubmitChecklist when testing your code ***

^ permalink raw reply	[flat|nested] 5+ messages in thread
* Re: [Fastboot] [PATCH] Avoid hypervisor statistics calculation in real mode
  2007-03-21  5:51   ` Mohan Kumar M
  2007-03-21 15:30     ` Randy Dunlap
@ 2007-03-23  6:18     ` Horms
  1 sibling, 0 replies; 5+ messages in thread
From: Horms @ 2007-03-23  6:18 UTC (permalink / raw)
  To: Mohan Kumar M; +Cc: Randy Dunlap, linuxppc-dev, fastboot, anton, paulus

On Wed, Mar 21, 2007 at 11:21:32AM +0530, Mohan Kumar M wrote:
> Thanks Randy.
> 
> I updated the patch as per your suggestions.
> 
> 
> kexec invokes plpar_hcall hypervisor call in real mode. plpar_hcall
> refers per cpu variable for accounting hypervisor statistics. These
> variables may not be present in the RMO region. So it results in
> 0x300 exception.
> 
> The following patch fixes this problem by using raw hypervisor call
> which does not update the hypervisor call statistics. Thanks to Anton
> for suggesting this idea.

This seems like a lot of code for a very slight variation
on an existing call. But I guess its cleaner than doing an "if" 
inside the assembler.

Funtionality-wise, it seems fine to me. Though I am most defianatly
not an authority on power.

I have put a minor comment inline.

> Cc: Anton Blanchard <anton@samba.org>
> Signed-off-by: Mohan Kumar M <mohan@in.ibm.com>
> ---
>  arch/powerpc/platforms/pseries/hvCall.S         |   34 ++++++++++++++++++++++++
>  arch/powerpc/platforms/pseries/lpar.c           |    2 -
>  arch/powerpc/platforms/pseries/plpar_wrappers.h |   16 +++++++++++
>  include/asm-powerpc/hvcall.h                    |   14 +++++++++
>  4 files changed, 65 insertions(+), 1 deletion(-)
> 
> Index: linux-2.6.21-rc4/arch/powerpc/platforms/pseries/hvCall.S
> ===================================================================
> --- linux-2.6.21-rc4.orig/arch/powerpc/platforms/pseries/hvCall.S
> +++ linux-2.6.21-rc4/arch/powerpc/platforms/pseries/hvCall.S
> @@ -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.
> + */

This text makes a little more sense to me:

/* 
 * plpar_hcall_raw may be called in real mode. In particular this may occur
 * during kexec/kdump. plpar_hcall_raw is a variation of plpar_hcall that
 * does not access the per cpu hypervisor call statistics variables, as
 * these variables may not be present in the RMO region.
 */

-- 
Horms
  H: http://www.vergenet.net/~horms/
  W: http://www.valinux.co.jp/en/

> +_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
>  
> Index: linux-2.6.21-rc4/arch/powerpc/platforms/pseries/lpar.c
> ===================================================================
> --- linux-2.6.21-rc4.orig/arch/powerpc/platforms/pseries/lpar.c
> +++ linux-2.6.21-rc4/arch/powerpc/platforms/pseries/lpar.c
> @@ -378,7 +378,7 @@ static void pSeries_lpar_hptab_clear(voi
>  
>  	/* 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);
>  }
>  
>  /*
> Index: linux-2.6.21-rc4/arch/powerpc/platforms/pseries/plpar_wrappers.h
> ===================================================================
> --- linux-2.6.21-rc4.orig/arch/powerpc/platforms/pseries/plpar_wrappers.h
> +++ linux-2.6.21-rc4/arch/powerpc/platforms/pseries/plpar_wrappers.h
> @@ -78,6 +78,22 @@ static inline long plpar_pte_remove(unsi
>  	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)
>  {
> Index: linux-2.6.21-rc4/include/asm-powerpc/hvcall.h
> ===================================================================
> --- linux-2.6.21-rc4.orig/include/asm-powerpc/hvcall.h
> +++ linux-2.6.21-rc4/include/asm-powerpc/hvcall.h
> @@ -237,6 +237,20 @@ long plpar_hcall_norets(unsigned long op
>  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.
>   * @retbuf: Buffer to store up to 9 return arguments in.
> _______________________________________________
> fastboot mailing list
> fastboot@lists.linux-foundation.org
> https://lists.linux-foundation.org/mailman/listinfo/fastboot

^ permalink raw reply	[flat|nested] 5+ messages in thread
end of thread, other threads:[~2007-03-23  6:38 UTC | newest]

Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2007-03-20 13:35 [PATCH] Avoid hypervisor statistics calculation in real mode Mohan Kumar M
2007-03-20 22:37 ` [Fastboot] " Randy Dunlap
2007-03-21  5:51   ` Mohan Kumar M
2007-03-21 15:30     ` Randy Dunlap
2007-03-23  6:18     ` Horms

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