Re: [kvm-unit-tests PATCH 11/14] powerpc/ppc64: add rtas_power_off

[David Gibson <david@gibson.dropbear.id.au>]

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On Mon, Aug 03, 2015 at 04:41:28PM +0200, Andrew Jones wrote:
> Add enough RTAS support to support power-off, and apply it to
> exit().
> 
> Signed-off-by: Andrew Jones <drjones@redhat.com>
> ---
>  lib/powerpc/asm/rtas.h  | 27 ++++++++++++++++
>  lib/powerpc/io.c        |  3 ++
>  lib/powerpc/rtas.c      | 84 +++++++++++++++++++++++++++++++++++++++++++++++++
>  lib/ppc64/asm/rtas.h    |  1 +
>  powerpc/Makefile.common |  1 +
>  powerpc/cstart64.S      |  9 ++++++
>  6 files changed, 125 insertions(+)
>  create mode 100644 lib/powerpc/asm/rtas.h
>  create mode 100644 lib/powerpc/rtas.c
>  create mode 100644 lib/ppc64/asm/rtas.h
> 
> diff --git a/lib/powerpc/asm/rtas.h b/lib/powerpc/asm/rtas.h
> new file mode 100644
> index 0000000000000..53ce126c69a42
> --- /dev/null
> +++ b/lib/powerpc/asm/rtas.h
> @@ -0,0 +1,27 @@
> +#ifndef _ASMPOWERPC_RTAS_H_
> +#define _ASMPOWERPC_RTAS_H_
> +/*
> + * Copyright (C) 2015, Red Hat Inc, Andrew Jones <drjones@redhat.com>
> + *
> + * This work is licensed under the terms of the GNU LGPL, version 2.
> + */
> +#include <libcflat.h>
> +
> +#define RTAS_UNKNOWN_SERVICE	(-1)
> +
> +struct rtas_args {
> +	u32 token;
> +	u32 nargs;
> +	u32 nret;
> +	u32 args[16];
> +	u32 *rets;
> +};
> +
> +extern void rtas_init(void);
> +extern void enter_rtas(unsigned long args);
> +extern int rtas_token(const char *service);
> +extern int rtas_call(int token, int nargs, int nret, int *outputs, ...);
> +
> +extern void rtas_power_off(void);
> +
> +#endif /* _ASMPOWERPC_RTAS_H_ */
> diff --git a/lib/powerpc/io.c b/lib/powerpc/io.c
> index a7eaafeca9205..25cdd0ad961ee 100644
> --- a/lib/powerpc/io.c
> +++ b/lib/powerpc/io.c
> @@ -7,6 +7,7 @@
>   */
>  #include <libcflat.h>
>  #include <asm/spinlock.h>
> +#include <asm/rtas.h>
>  
>  extern void halt(int code);
>  extern void putchar(int c);
> @@ -15,6 +16,7 @@ static struct spinlock uart_lock;
>  
>  void io_init(void)
>  {
> +	rtas_init();
>  }
>  
>  void puts(const char *s)
> @@ -27,5 +29,6 @@ void puts(const char *s)
>  
>  void exit(int code)
>  {
> +	rtas_power_off();
>  	halt(code);
>  }
> diff --git a/lib/powerpc/rtas.c b/lib/powerpc/rtas.c
> new file mode 100644
> index 0000000000000..39f7d4428ee77
> --- /dev/null
> +++ b/lib/powerpc/rtas.c
> @@ -0,0 +1,84 @@
> +/*
> + * powerpc RTAS
> + *
> + * Copyright (C) 2015, Red Hat Inc, Andrew Jones <drjones@redhat.com>
> + *
> + * This work is licensed under the terms of the GNU LGPL, version 2.
> + */
> +#include <libcflat.h>
> +#include <libfdt/libfdt.h>
> +#include <devicetree.h>
> +#include <asm/spinlock.h>
> +#include <asm/io.h>
> +#include <asm/rtas.h>
> +
> +static struct spinlock lock;
> +struct rtas_args rtas_args;
> +static int rtas_node;
> +
> +void rtas_init(void)
> +{
> +	if (!dt_available()) {
> +		printf("%s: No device tree!\n", __func__);
> +		abort();
> +	}
> +
> +	rtas_node = fdt_path_offset(dt_fdt(), "/rtas");
> +	if (rtas_node < 0) {
> +		printf("%s: /rtas node: %s\n", __func__,
> +			fdt_strerror(rtas_node));
> +		abort();
> +	}
> +}
> +
> +int rtas_token(const char *service)
> +{
> +	const struct fdt_property *prop;
> +	u32 *token;
> +
> +	prop = fdt_get_property(dt_fdt(), rtas_node, service, NULL);

Oh.. one other thing here.

This is only safe if you never alter the device tree blob you're given
(or at least, not after rtas_init()).  That may well be the case, but
I don't know your code well enough to be sure.

Otherwise, the rtas node could get moved by other dt changes, meaning
the offset stored in rtas_node is no longer valid.

> +	if (prop) {
> +		token = (u32 *)prop->data;
> +		return fdt32_to_cpu(*token);
> +	}
> +	return RTAS_UNKNOWN_SERVICE;
> +}
> +
> +int rtas_call(int token, int nargs, int nret, int *outputs, ...)
> +{
> +	va_list list;
> +	int ret, i;
> +
> +	spin_lock(&lock);
> +
> +	rtas_args.token = cpu_to_be32(token);
> +	rtas_args.nargs = cpu_to_be32(nargs);
> +	rtas_args.nret = cpu_to_be32(nret);
> +	rtas_args.rets = &rtas_args.args[nargs];
> +
> +	va_start(list, outputs);
> +	for (i = 0; i < nargs; ++i)
> +		rtas_args.args[i] = cpu_to_be32(va_arg(list, u32));
> +	va_end(list);
> +
> +	for (i = 0; i < nret; ++i)
> +		rtas_args.rets[i] = 0;
> +
> +	enter_rtas(__pa(&rtas_args));
> +
> +	if (nret > 1 && outputs != NULL)
> +		for (i = 0; i < nret - 1; ++i)
> +			outputs[i] = be32_to_cpu(rtas_args.rets[i + 1]);
> +
> +	ret = nret > 0 ? be32_to_cpu(rtas_args.rets[0]) : 0;
> +
> +	spin_unlock(&lock);
> +	return ret;
> +}
> +
> +void rtas_power_off(void)
> +{
> +	printf("RTAS power-off returned %d\n",
> +		rtas_call(rtas_token("power-off"), 2, 1, NULL, -1, -1));
> +	assert(0);
> +}
> diff --git a/lib/ppc64/asm/rtas.h b/lib/ppc64/asm/rtas.h
> new file mode 100644
> index 0000000000000..fe77f635cd860
> --- /dev/null
> +++ b/lib/ppc64/asm/rtas.h
> @@ -0,0 +1 @@
> +#include "../../powerpc/asm/rtas.h"
> diff --git a/powerpc/Makefile.common b/powerpc/Makefile.common
> index b130342dee60e..f4eff7f8eccb4 100644
> --- a/powerpc/Makefile.common
> +++ b/powerpc/Makefile.common
> @@ -39,6 +39,7 @@ cflatobjs += lib/powerpc/io.o
>  cflatobjs += lib/powerpc/setup.o
>  cflatobjs += lib/powerpc/mmu.o
>  cflatobjs += lib/powerpc/smp.o
> +cflatobjs += lib/powerpc/rtas.o
>  
>  libgcc := $(shell $(CC) $(machine) --print-libgcc-file-name)
>  start_addr := $(shell printf "%x\n" $$(( $(phys_base) + $(kernel_offset) )))
> diff --git a/powerpc/cstart64.S b/powerpc/cstart64.S
> index 8edaaa6e251fc..1c48083efa33c 100644
> --- a/powerpc/cstart64.S
> +++ b/powerpc/cstart64.S
> @@ -8,6 +8,7 @@
>  
>  #define HVSC			.long 0x44000022
>  #define H_PUT_TERM_CHAR		0x58
> +#define KVMPPC_H_RTAS		0xf000
>  
>  #define LOAD_REG_IMMEDIATE(reg,expr)		\
>  	lis	reg,(expr)@highest;		\
> @@ -85,3 +86,11 @@ putchar:
>  	li	r5, 1	/* sending just 1 byte */
>  	HVSC
>  	blr
> +
> +.globl enter_rtas
> +enter_rtas:
> +	mr	r4, r3
> +	lis	r3, KVMPPC_H_RTAS@h
> +	ori	r3, r3, KVMPPC_H_RTAS@l
> +	HVSC
> +	blr

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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