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From: Michael Ellerman <mpe@ellerman.id.au>
To: Hari Bathini <hbathini@linux.ibm.com>,
	linuxppc-dev <linuxppc-dev@ozlabs.org>
Cc: Ananth N Mavinakayanahalli <ananth@linux.ibm.com>,
	Mahesh J Salgaonkar <mahesh@linux.ibm.com>,
	Vasant Hegde <hegdevasant@linux.ibm.com>,
	Oliver <oohall@gmail.com>, Nicholas Piggin <npiggin@gmail.com>,
	Daniel Axtens <dja@axtens.net>
Subject: Re: [PATCH v5 12/31] powernv/fadump: register kernel metadata address with opal
Date: Wed, 04 Sep 2019 21:25:15 +1000
Message-ID: <87a7bkqp5w.fsf@mpe.ellerman.id.au> (raw)
In-Reply-To: <156630273573.8896.13875969842131147431.stgit@hbathini.in.ibm.com>

Hari Bathini <hbathini@linux.ibm.com> writes:
> diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c
> index b8061fb9..a086a09 100644
> --- a/arch/powerpc/kernel/fadump.c
> +++ b/arch/powerpc/kernel/fadump.c
> @@ -283,17 +286,17 @@ static void __init fadump_reserve_crash_area(unsigned long base,
>  
>  int __init fadump_reserve_mem(void)
>  {
> +	int ret = 1;
>  	unsigned long base, size, memory_boundary;

Please try to use reverse christmas tree style when possible.

> @@ -363,29 +366,43 @@ int __init fadump_reserve_mem(void)
>  		 * use memblock_find_in_range() here since it doesn't allocate
>  		 * from bottom to top.
>  		 */
> -		for (base = fw_dump.boot_memory_size;
> -		     base <= (memory_boundary - size);
> -		     base += size) {
> +		while (base <= (memory_boundary - size)) {
>  			if (memblock_is_region_memory(base, size) &&
>  			    !memblock_is_region_reserved(base, size))
>  				break;
> +
> +			base += size;
>  		}

Some of these changes look like they might not be necessary in this
patch, ie. could be split out into a lead-up patch. eg. the conversion
from for to while. But it's a bit hard to tell.

> diff --git a/arch/powerpc/platforms/powernv/opal-fadump.c b/arch/powerpc/platforms/powernv/opal-fadump.c
> index e330877..e5c4700 100644
> --- a/arch/powerpc/platforms/powernv/opal-fadump.c
> +++ b/arch/powerpc/platforms/powernv/opal-fadump.c
> @@ -13,14 +13,86 @@
>  #include <linux/seq_file.h>
>  #include <linux/of_fdt.h>
>  #include <linux/libfdt.h>
> +#include <linux/mm.h>
>  
> +#include <asm/page.h>
>  #include <asm/opal.h>
>  
>  #include "../../kernel/fadump-common.h"
> +#include "opal-fadump.h"
> +
> +static struct opal_fadump_mem_struct *opal_fdm;
> +
> +/* Initialize kernel metadata */
> +static void opal_fadump_init_metadata(struct opal_fadump_mem_struct *fdm)
> +{
> +	fdm->version = OPAL_FADUMP_VERSION;
> +	fdm->region_cnt = 0;
> +	fdm->registered_regions = 0;
> +	fdm->fadumphdr_addr = 0;
> +}
>  
>  static ulong opal_fadump_init_mem_struct(struct fw_dump *fadump_conf)
>  {
> -	return fadump_conf->reserve_dump_area_start;
> +	ulong addr = fadump_conf->reserve_dump_area_start;

I just noticed you're using ulong, which I haven't seen much before. KVM
uses it a lot but not much else.

Because this is all 64-bit only code I'd probably rather you just use
u64 explicitly to avoid anyone having to think about it.

> +
> +	opal_fdm = __va(fadump_conf->kernel_metadata);
> +	opal_fadump_init_metadata(opal_fdm);
> +
> +	opal_fdm->region_cnt = 1;
> +	opal_fdm->rgn[0].src	= RMA_START;
> +	opal_fdm->rgn[0].dest	= addr;
> +	opal_fdm->rgn[0].size	= fadump_conf->boot_memory_size;
> +	addr += fadump_conf->boot_memory_size;
> +
> +	/*
> +	 * Kernel metadata is passed to f/w and retrieved in capture kerenl.
> +	 * So, use it to save fadump header address instead of calculating it.
> +	 */
> +	opal_fdm->fadumphdr_addr = (opal_fdm->rgn[0].dest +
> +				    fadump_conf->boot_memory_size);
> +
> +	return addr;
> +}
> +
> +static ulong opal_fadump_get_metadata_size(void)
> +{
> +	ulong size = sizeof(struct opal_fadump_mem_struct);
> +
> +	size = PAGE_ALIGN(size);
> +	return size;

	return PAGE_ALIGN(sizeof(struct opal_fadump_mem_struct));

???

> diff --git a/arch/powerpc/platforms/powernv/opal-fadump.h b/arch/powerpc/platforms/powernv/opal-fadump.h
> new file mode 100644
> index 0000000..19cac1f
> --- /dev/null
> +++ b/arch/powerpc/platforms/powernv/opal-fadump.h
> @@ -0,0 +1,33 @@
> +/* SPDX-License-Identifier: GPL-2.0-or-later */
> +/*
> + * Firmware-Assisted Dump support on POWER platform (OPAL).
> + *
> + * Copyright 2019, IBM Corp.
> + * Author: Hari Bathini <hbathini@linux.ibm.com>
> + */
> +
> +#ifndef __PPC64_OPAL_FA_DUMP_H__
> +#define __PPC64_OPAL_FA_DUMP_H__

Usual style is _ASM_POWERPC_OPAL_FADUMP_H.


> +/* OPAL FADump structure format version */
> +#define OPAL_FADUMP_VERSION			0x1

What is the meaning of this version? How/can we change it. What does it
mean if it's a different number? Please provide some comments or doco
describing how it's expected to be used.

We're defining some sort of ABI here and I want to understand/have
better documentation on what the implications of that are.

> diff --git a/arch/powerpc/platforms/pseries/rtas-fadump.c b/arch/powerpc/platforms/pseries/rtas-fadump.c
> index 2b94392..4111ee9 100644
> --- a/arch/powerpc/platforms/pseries/rtas-fadump.c
> +++ b/arch/powerpc/platforms/pseries/rtas-fadump.c
> @@ -121,6 +121,21 @@ static ulong rtas_fadump_init_mem_struct(struct fw_dump *fadump_conf)
>  	return addr;
>  }
>  
> +/*
> + * On this platform, the metadata struture is passed while registering
> + * for FADump and the same is returned by f/w in capture kernel.
> + * No additional provision to setup kernel metadata separately.
> + */
> +static ulong rtas_fadump_get_metadata_size(void)
> +{
> +	return 0;
> +}
> +
> +static int rtas_fadump_setup_metadata(struct fw_dump *fadump_conf)
> +{
> +	return 0;
> +}

Each of these uses about 16 byes of text as well as space in the symbol
table. I think there's only one call site for each, so allowing the
callback to be NULL and skipping the call when it is would be slightly
more efficient.


> @@ -486,9 +501,10 @@ static void rtas_fadump_trigger(struct fadump_crash_info_header *fdh,
>  	rtas_os_term((char *)msg);
>  }
>  
> -
>  static struct fadump_ops rtas_fadump_ops = {
>  	.fadump_init_mem_struct		= rtas_fadump_init_mem_struct,
> +	.fadump_get_metadata_size	= rtas_fadump_get_metadata_size,
> +	.fadump_setup_metadata		= rtas_fadump_setup_metadata,
>  	.fadump_register		= rtas_fadump_register,
>  	.fadump_unregister		= rtas_fadump_unregister,
>  	.fadump_invalidate		= rtas_fadump_invalidate,

cheers

  reply index

Thread overview: 74+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-20 12:04 [PATCH v5 00/31] Add FADump support on PowerNV platform Hari Bathini
2019-08-20 12:04 ` [PATCH v5 01/31] powerpc/fadump: move internal macros/definitions to a new header Hari Bathini
2019-09-03 11:09   ` Michael Ellerman
2019-09-03 16:05     ` Hari Bathini
2019-08-20 12:04 ` [PATCH v5 02/31] powerpc/fadump: move internal code to a new file Hari Bathini
2019-09-03 11:09   ` Michael Ellerman
2019-09-03 16:05     ` Hari Bathini
2019-09-04  9:02       ` Mahesh Jagannath Salgaonkar
2019-09-04 18:26         ` Hari Bathini
2019-08-20 12:04 ` [PATCH v5 03/31] powerpc/fadump: Improve fadump documentation Hari Bathini
2019-08-20 12:04 ` [PATCH v5 04/31] pseries/fadump: move rtas specific definitions to platform code Hari Bathini
2019-08-20 12:04 ` [PATCH v5 05/31] pseries/fadump: introduce callbacks for platform specific operations Hari Bathini
2019-09-03 11:10   ` Michael Ellerman
2019-09-03 16:06     ` Hari Bathini
2019-09-06  6:39       ` Hari Bathini
2019-08-20 12:04 ` [PATCH v5 06/31] pseries/fadump: define register/un-register callback functions Hari Bathini
2019-09-03 11:10   ` Michael Ellerman
2019-09-03 17:15     ` Hari Bathini
2019-08-20 12:04 ` [PATCH v5 07/31] powerpc/fadump: release all the memory above boot memory size Hari Bathini
2019-09-03 11:10   ` Michael Ellerman
2019-09-03 16:27     ` Hari Bathini
2019-08-20 12:05 ` [PATCH v5 08/31] pseries/fadump: move out platform specific support from generic code Hari Bathini
2019-08-20 12:05 ` [PATCH v5 09/31] powerpc/fadump: use FADump instead of fadump for how it is pronounced Hari Bathini
2019-08-20 12:05 ` [PATCH v5 10/31] opal: add MPIPL interface definitions Hari Bathini
2019-09-03 11:10   ` Michael Ellerman
2019-09-03 16:28     ` Hari Bathini
2019-09-04 11:03       ` Michael Ellerman
2019-09-04 11:05   ` Michael Ellerman
2019-08-20 12:05 ` [PATCH v5 11/31] powernv/fadump: add fadump support on powernv Hari Bathini
2019-09-03 11:10   ` Michael Ellerman
2019-09-03 16:31     ` Hari Bathini
2019-09-04 14:33       ` Hari Bathini
2019-09-05  3:11         ` Michael Ellerman
2019-08-20 12:05 ` [PATCH v5 12/31] powernv/fadump: register kernel metadata address with opal Hari Bathini
2019-09-04 11:25   ` Michael Ellerman [this message]
2019-08-20 12:05 ` [PATCH v5 13/31] powernv/fadump: reset metadata address during clean up Hari Bathini
2019-08-27 12:00   ` Hari Bathini
2019-08-20 12:05 ` [PATCH v5 14/31] powernv/fadump: define register/un-register callback functions Hari Bathini
2019-09-05  4:15   ` Michael Ellerman
2019-09-05  7:23   ` Michael Ellerman
2019-09-05  9:54     ` Hari Bathini
2019-08-20 12:05 ` [PATCH v5 15/31] powernv/fadump: support copying multiple kernel boot memory regions Hari Bathini
2019-09-04 11:30   ` Michael Ellerman
2019-09-04 20:20     ` Hari Bathini
2019-09-05  3:13       ` Michael Ellerman
2019-08-20 12:06 ` [PATCH v5 16/31] powernv/fadump: process the crashdump by exporting it as /proc/vmcore Hari Bathini
2019-09-04 11:42   ` Michael Ellerman
2019-09-04 21:01     ` Hari Bathini
2019-08-20 12:06 ` [PATCH v5 17/31] powernv/fadump: Warn before processing partial crashdump Hari Bathini
2019-09-04 11:48   ` Michael Ellerman
2019-08-20 12:06 ` [PATCH v5 18/31] powernv/fadump: handle invalidation of crashdump and re-registraion Hari Bathini
2019-08-20 12:06 ` [PATCH v5 19/31] powerpc/fadump: Update documentation about OPAL platform support Hari Bathini
2019-09-04 11:51   ` Michael Ellerman
2019-09-04 12:08     ` Oliver O'Halloran
2019-09-05  3:15       ` Michael Ellerman
2019-08-20 12:06 ` [PATCH v5 20/31] powerpc/fadump: use smaller offset while finding memory for reservation Hari Bathini
2019-09-04 11:54   ` Michael Ellerman
2019-08-20 12:06 ` [PATCH v5 21/31] powernv/fadump: process architected register state data provided by firmware Hari Bathini
2019-09-04 12:20   ` Michael Ellerman
2019-09-09 13:23     ` Hari Bathini
2019-09-09 15:33       ` Oliver O'Halloran
2019-09-10  8:48         ` Hari Bathini
2019-09-10 14:05           ` Michael Ellerman
2019-09-10 16:10             ` Hari Bathini
2019-08-20 12:06 ` [PATCH v5 22/31] powerpc/fadump: make crash memory ranges array allocation generic Hari Bathini
2019-08-20 12:06 ` [PATCH v5 23/31] powerpc/fadump: consider reserved ranges while releasing memory Hari Bathini
2019-08-20 12:07 ` [PATCH v5 24/31] powerpc/fadump: improve how crashed kernel's memory is reserved Hari Bathini
2019-08-20 12:07 ` [PATCH v5 25/31] powernv/fadump: add support to preserve crash data on FADUMP disabled kernel Hari Bathini
2019-08-20 12:07 ` [PATCH v5 26/31] powerpc/fadump: update documentation about CONFIG_PRESERVE_FA_DUMP Hari Bathini
2019-08-20 12:07 ` [PATCH v5 27/31] powernv/opalcore: export /sys/firmware/opal/core for analysing opal crashes Hari Bathini
2019-08-20 12:07 ` [PATCH v5 28/31] powernv/opalcore: provide an option to invalidate /sys/firmware/opal/core file Hari Bathini
2019-08-20 12:07 ` [PATCH v5 29/31] powerpc/fadump: consider f/w load area Hari Bathini
2019-08-20 12:07 ` [PATCH v5 30/31] powernv/fadump: update documentation about option to release opalcore Hari Bathini
2019-08-20 12:07 ` [PATCH v5 31/31] powernv/fadump: support holes in kernel boot memory area Hari Bathini

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