Re: [kvm-unit-tests PATCH v6 17/18] powerpc/ppc64: add RTAS support

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

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On Fri, Feb 19, 2016 at 04:58:22PM +0100, Andrew Jones wrote:
> Add enough RTAS support to start adding RTAS commands. Just add
> power-off for now.
> 
> Signed-off-by: Andrew Jones <drjones@redhat.com>
> Reviewed-by: Thomas Huth <thuth@redhat.com>
> Tested-by: Laurent Vivier <lvivier@redhat.com>
> Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
> ---
>  lib/powerpc/asm/rtas.h  |  26 +++++++++
>  lib/powerpc/io.c        |   2 +
>  lib/powerpc/rtas.c      | 139 ++++++++++++++++++++++++++++++++++++++++++++++++
>  lib/ppc64/asm/rtas.h    |   1 +
>  powerpc/Makefile.common |   1 +
>  5 files changed, 169 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..522225bcb6de3
> --- /dev/null
> +++ b/lib/powerpc/asm/rtas.h
> @@ -0,0 +1,26 @@
> +#ifndef _ASMPOWERPC_RTAS_H_
> +#define _ASMPOWERPC_RTAS_H_
> +/*
> + * Copyright (C) 2016, 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 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 ef90946fb1131..c4c61ea8ac1cf 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 print_lock;
>  
>  void io_init(void)
>  {
> +	rtas_init();
>  }
>  
>  void puts(const char *s)
> diff --git a/lib/powerpc/rtas.c b/lib/powerpc/rtas.c
> new file mode 100644
> index 0000000000000..464d066d3c220
> --- /dev/null
> +++ b/lib/powerpc/rtas.c
> @@ -0,0 +1,139 @@
> +/*
> + * powerpc RTAS
> + *
> + * Copyright (C) 2016, 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/hcall.h>
> +#include <asm/io.h>
> +#include <asm/rtas.h>
> +
> +#define RTAS_BLOB_WORDS 8
> +
> +#if defined(__powerpc64__)
> +struct func_ptr {
> +	unsigned long ptr;
> +	unsigned long toc;
> +};
> +static struct func_ptr rtas_entry_funcptr;
> +#endif
> +static u32 rtas_blob[RTAS_BLOB_WORDS];
> +typedef void (*rtas_entry_t)(unsigned long);
> +static rtas_entry_t enter_rtas;
> +static struct rtas_args rtas_args;
> +static struct spinlock rtas_lock;
> +
> +static int rtas_node(void)
> +{
> +	int node = fdt_path_offset(dt_fdt(), "/rtas");
> +
> +	if (node < 0) {
> +		printf("%s: /rtas: %s\n", __func__, fdt_strerror(node));
> +		abort();
> +	}
> +
> +	return node;
> +}
> +
> +void rtas_init(void)
> +{
> +	bool broken_sc1 = hcall_have_broken_sc1();
> +	int node = rtas_node(), len, words, i;
> +	const struct fdt_property *prop;
> +	u32 *data, *insns;
> +
> +	if (!dt_available()) {
> +		printf("%s: No device tree!\n", __func__);
> +		abort();
> +	}
> +
> +	prop = fdt_get_property(dt_fdt(), node,
> +				"linux,rtas-entry", &len);
> +	if (!prop) {
> +		printf("%s: /rtas/linux,rtas-entry: %s\n",
> +				__func__, fdt_strerror(len));
> +		abort();
> +	}
> +
> +	data = (u32 *)prop->data;
> +	insns = (u32 *)(unsigned long)fdt32_to_cpu(*data);
> +
> +	prop = fdt_get_property(dt_fdt(), node, "rtas-size", &len);
> +	if (!prop) {
> +		printf("%s: /rtas/rtas-size: %s\n",
> +				__func__, fdt_strerror(len));
> +		abort();
> +	}
> +	data = (u32 *)prop->data;
> +	words = (int)fdt32_to_cpu(*data)/4;
> +	assert(words <= RTAS_BLOB_WORDS);
> +
> +	for (i = 0; i < words; ++i) {
> +		rtas_blob[i] = be32_to_cpu(insns[i]);
> +		if (broken_sc1 && rtas_blob[i] == SC1)
> +			rtas_blob[i] = SC1_REPLACEMENT;
> +	}

Hmm.. in general it's not guaranteed that you can copy around the RTAS
blob and have it still work.  But.. you're working essentially at the
same level as SLOF here, rather than a "normal" OS and I think SLOF
must make the same assumption.  So I guess it's ok.

> +#if defined(__powerpc64__)

Technically this ifdef should be based on the ABI version, rather than
__powerpc64__, but I'm not sure if there are standard #defines for that.

> +	rtas_entry_funcptr.ptr = (unsigned long)rtas_blob;
> +	enter_rtas = (rtas_entry_t)&rtas_entry_funcptr;
> +#else
> +	enter_rtas = (rtas_entry_t)rtas_blob;
> +#endif

I think you may want to have an actual coded enter_rtas function,
rather than just constructing a function pointer around the raw blob.
For one thing it should reduce the ugly ABI version #ifdefs.  More
importantly though, you can use it to set up the correct MSR state for
entry into RTAS (IR, DR, EE off, big-endian, ..).  At the moment all
your code runs in a suitable MSR state to call directly into RTAS, but
that will probably change fairly soon.


> +}
> +
> +int rtas_token(const char *service)
> +{
> +	const struct fdt_property *prop;
> +	u32 *token;
> +
> +	prop = fdt_get_property(dt_fdt(), rtas_node(), service, NULL);
> +	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(&rtas_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(&rtas_lock);
> +	return ret;
> +}
> +
> +void rtas_power_off(void)
> +{
> +	int ret = rtas_call(rtas_token("power-off"), 2, 1, NULL, -1, -1);
> +	printf("RTAS power-off returned %d\n", ret);

abort here?

> +}
> 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 07ba135f77110..cad728ecbe269 100644
> --- a/powerpc/Makefile.common
> +++ b/powerpc/Makefile.common
> @@ -28,6 +28,7 @@ cflatobjs += lib/devicetree.o
>  cflatobjs += lib/powerpc/io.o
>  cflatobjs += lib/powerpc/hcall.o
>  cflatobjs += lib/powerpc/setup.o
> +cflatobjs += lib/powerpc/rtas.o
>  
>  libgcc := $(shell $(CC) $(machine) --print-libgcc-file-name)
>  

-- 
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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