Patchwork [v11,5/8] KVM: PPC: ev_idle hcall support for e500 guests

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Submitter Stuart Yoder
Date June 22, 2012, 8:04 p.m.
Message ID <1340395469-14363-1-git-send-email-stuart.yoder@freescale.com>
Download mbox | patch
Permalink /patch/166671/
State New
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Comments

Stuart Yoder - June 22, 2012, 8:04 p.m.
From: Liu Yu-B13201 <Yu.Liu@freescale.com>

Signed-off-by: Liu Yu <yu.liu@freescale.com>
[varun: 64-bit changes]
Signed-off-by: Varun Sethi <Varun.Sethi@freescale.com>
Signed-off-by: Stuart Yoder <stuart.yoder@freescale.com>
---
-v11:
   -added comment about origin of idle instruction sequence
   -update for 64-bit support found in testing

 arch/powerpc/include/asm/epapr_hcalls.h |   11 +++++----
 arch/powerpc/kernel/epapr_hcalls.S      |   32 +++++++++++++++++++++++++++++++
 arch/powerpc/kernel/epapr_paravirt.c    |   11 +++++++++-
 3 files changed, 48 insertions(+), 6 deletions(-)
Alexander Graf - July 2, 2012, 12:20 p.m.
On 22.06.2012, at 22:04, Stuart Yoder wrote:

> From: Liu Yu-B13201 <Yu.Liu@freescale.com>
> 
> Signed-off-by: Liu Yu <yu.liu@freescale.com>
> [varun: 64-bit changes]
> Signed-off-by: Varun Sethi <Varun.Sethi@freescale.com>
> Signed-off-by: Stuart Yoder <stuart.yoder@freescale.com>
> ---
> -v11:
>   -added comment about origin of idle instruction sequence
>   -update for 64-bit support found in testing
> 
> arch/powerpc/include/asm/epapr_hcalls.h |   11 +++++----
> arch/powerpc/kernel/epapr_hcalls.S      |   32 +++++++++++++++++++++++++++++++
> arch/powerpc/kernel/epapr_paravirt.c    |   11 +++++++++-
> 3 files changed, 48 insertions(+), 6 deletions(-)
> 
> diff --git a/arch/powerpc/include/asm/epapr_hcalls.h b/arch/powerpc/include/asm/epapr_hcalls.h
> index c0c7adc..833ce2c 100644
> --- a/arch/powerpc/include/asm/epapr_hcalls.h
> +++ b/arch/powerpc/include/asm/epapr_hcalls.h
> @@ -50,10 +50,6 @@
> #ifndef _EPAPR_HCALLS_H
> #define _EPAPR_HCALLS_H
> 
> -#include <linux/types.h>
> -#include <linux/errno.h>
> -#include <asm/byteorder.h>
> -
> #define EV_BYTE_CHANNEL_SEND		1
> #define EV_BYTE_CHANNEL_RECEIVE		2
> #define EV_BYTE_CHANNEL_POLL		3
> @@ -109,6 +105,11 @@
> #define EV_UNIMPLEMENTED	12	/* Unimplemented hypercall */
> #define EV_BUFFER_OVERFLOW	13	/* Caller-supplied buffer too small */
> 
> +#ifndef __ASSEMBLY__
> +#include <linux/types.h>
> +#include <linux/errno.h>
> +#include <asm/byteorder.h>
> +
> /*
>  * Hypercall register clobber list
>  *
> @@ -506,5 +507,5 @@ static inline unsigned int ev_idle(void)
> 
> 	return r3;
> }
> -
> +#endif /* !__ASSEMBLY__ */
> #endif
> diff --git a/arch/powerpc/kernel/epapr_hcalls.S b/arch/powerpc/kernel/epapr_hcalls.S
> index 697b390..eb19377 100644
> --- a/arch/powerpc/kernel/epapr_hcalls.S
> +++ b/arch/powerpc/kernel/epapr_hcalls.S
> @@ -8,13 +8,45 @@
>  */
> 
> #include <linux/threads.h>
> +#include <asm/epapr_hcalls.h>
> #include <asm/reg.h>
> #include <asm/page.h>
> #include <asm/cputable.h>
> #include <asm/thread_info.h>
> #include <asm/ppc_asm.h>
> +#include <asm/asm-compat.h>
> #include <asm/asm-offsets.h>
> 
> +/* epapr_ev_idle() was derived from e500_idle() */
> +_GLOBAL(epapr_ev_idle)
> +#ifndef CONFIG_PPC64
> +	rlwinm	r3, r1, 0, 0, 31-THREAD_SHIFT	/* current thread_info */
> +#else
> +	clrrdi	r3, r1, THREAD_SHIFT
> +#endif

Ben, would you be opposed to a macro that does this? Open-coding subtile details like this always makes me wary we could screw them up :)


Alex

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Benjamin Herrenschmidt - July 2, 2012, 1:24 p.m.
On Mon, 2012-07-02 at 14:20 +0200, Alexander Graf wrote:
> 
> Ben, would you be opposed to a macro that does this? Open-coding
> subtile details like this always makes me wary we could screw them
> up :)

That's definitely material for a macro (and fixup the gazillion places
where we do it by hand already :-)

Cheers,
Ben.


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Alexander Graf - July 2, 2012, 1:40 p.m.
On 02.07.2012, at 15:24, Benjamin Herrenschmidt wrote:

> On Mon, 2012-07-02 at 14:20 +0200, Alexander Graf wrote:
>> 
>> Ben, would you be opposed to a macro that does this? Open-coding
>> subtile details like this always makes me wary we could screw them
>> up :)
> 
> That's definitely material for a macro (and fixup the gazillion places
> where we do it by hand already :-)

Just like I thought.

Stuart, want to take this on you? It'd be mostly a simple search+replace of the pattern in question with a macro GET_THREAD_INFO(r3, r1) that does the same thing as the code we have today, but makes it easier to read.


Alex

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Patch

diff --git a/arch/powerpc/include/asm/epapr_hcalls.h b/arch/powerpc/include/asm/epapr_hcalls.h
index c0c7adc..833ce2c 100644
--- a/arch/powerpc/include/asm/epapr_hcalls.h
+++ b/arch/powerpc/include/asm/epapr_hcalls.h
@@ -50,10 +50,6 @@ 
 #ifndef _EPAPR_HCALLS_H
 #define _EPAPR_HCALLS_H
 
-#include <linux/types.h>
-#include <linux/errno.h>
-#include <asm/byteorder.h>
-
 #define EV_BYTE_CHANNEL_SEND		1
 #define EV_BYTE_CHANNEL_RECEIVE		2
 #define EV_BYTE_CHANNEL_POLL		3
@@ -109,6 +105,11 @@ 
 #define EV_UNIMPLEMENTED	12	/* Unimplemented hypercall */
 #define EV_BUFFER_OVERFLOW	13	/* Caller-supplied buffer too small */
 
+#ifndef __ASSEMBLY__
+#include <linux/types.h>
+#include <linux/errno.h>
+#include <asm/byteorder.h>
+
 /*
  * Hypercall register clobber list
  *
@@ -506,5 +507,5 @@  static inline unsigned int ev_idle(void)
 
 	return r3;
 }
-
+#endif /* !__ASSEMBLY__ */
 #endif
diff --git a/arch/powerpc/kernel/epapr_hcalls.S b/arch/powerpc/kernel/epapr_hcalls.S
index 697b390..eb19377 100644
--- a/arch/powerpc/kernel/epapr_hcalls.S
+++ b/arch/powerpc/kernel/epapr_hcalls.S
@@ -8,13 +8,45 @@ 
  */
 
 #include <linux/threads.h>
+#include <asm/epapr_hcalls.h>
 #include <asm/reg.h>
 #include <asm/page.h>
 #include <asm/cputable.h>
 #include <asm/thread_info.h>
 #include <asm/ppc_asm.h>
+#include <asm/asm-compat.h>
 #include <asm/asm-offsets.h>
 
+/* epapr_ev_idle() was derived from e500_idle() */
+_GLOBAL(epapr_ev_idle)
+#ifndef CONFIG_PPC64
+	rlwinm	r3, r1, 0, 0, 31-THREAD_SHIFT	/* current thread_info */
+#else
+	clrrdi	r3, r1, THREAD_SHIFT
+#endif
+	PPC_LL	r4, TI_LOCAL_FLAGS(r3)	/* set napping bit */
+	ori	r4, r4,_TLF_NAPPING	/* so when we take an exception */
+	PPC_STL	r4, TI_LOCAL_FLAGS(r3)	/* it will return to our caller */
+
+	wrteei	1
+
+idle_loop:
+	LOAD_REG_IMMEDIATE(r11, EV_HCALL_TOKEN(EV_IDLE))
+
+.global epapr_ev_idle_start
+epapr_ev_idle_start:
+	li	r3, -1
+	nop
+	nop
+	nop
+
+	/*
+	 * Guard against spurious wakeups from a hypervisor --
+	 * only interrupt will cause us to return to LR due to
+	 * _TLF_NAPPING.
+	 */
+	b	idle_loop
+
 /* Hypercall entry point. Will be patched with device tree instructions. */
 .global epapr_hypercall_start
 epapr_hypercall_start:
diff --git a/arch/powerpc/kernel/epapr_paravirt.c b/arch/powerpc/kernel/epapr_paravirt.c
index 028aeae..f3eab85 100644
--- a/arch/powerpc/kernel/epapr_paravirt.c
+++ b/arch/powerpc/kernel/epapr_paravirt.c
@@ -21,6 +21,10 @@ 
 #include <asm/epapr_hcalls.h>
 #include <asm/cacheflush.h>
 #include <asm/code-patching.h>
+#include <asm/machdep.h>
+
+extern void epapr_ev_idle(void);
+extern u32 epapr_ev_idle_start[];
 
 bool epapr_paravirt_enabled;
 
@@ -41,8 +45,13 @@  static int __init epapr_paravirt_init(void)
 	if (len % 4 || len > (4 * 4))
 		return -ENODEV;
 
-	for (i = 0; i < (len / 4); i++)
+	for (i = 0; i < (len / 4); i++) {
 		patch_instruction(epapr_hypercall_start + i, insts[i]);
+		patch_instruction(epapr_ev_idle_start + i, insts[i]);
+	}
+
+	if (of_get_property(hyper_node, "has-idle", NULL))
+		ppc_md.power_save = epapr_ev_idle;
 
 	epapr_paravirt_enabled = true;