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Date:   Fri, 30 Nov 2018 11:37:03 +0800
From:   Dave Young <dyoung@redhat.com>
To:     Lianbo Jiang <lijiang@redhat.com>
Cc:     linux-kernel@vger.kernel.org, kexec@lists.infradead.org,
        x86@kernel.org, linux-ia64@vger.kernel.org,
        linux-efi@vger.kernel.org, tglx@linutronix.de, mingo@redhat.com,
        bp@alien8.de, akpm@linux-foundation.org,
        dave.hansen@linux.intel.com, luto@kernel.org, peterz@infradead.org,
        ard.biesheuvel@linaro.org, tony.luck@intel.com,
        fenghua.yu@intel.com, bhe@redhat.com,
        Tom Lendacky <thomas.lendacky@amd.com>,
        Toshi Kani <toshi.kani@hp.com>,
        Dan Williams <dan.j.williams@intel.com>
Subject: Re: [PATCH 1/2 v8] resource: add the new I/O resource descriptor
 'IORES_DESC_RESERVED'
Message-ID: <20181130033703.GA23624@dhcp-128-65.nay.redhat.com>
References: <20181129080956.20776-1-lijiang@redhat.com>
 <20181129080956.20776-2-lijiang@redhat.com>
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+ more people

On 11/29/18 at 04:09pm, Lianbo Jiang wrote:
> When doing kexec_file_load, the first kernel needs to pass the e820
> reserved ranges to the second kernel. But kernel can not exactly
> match the e820 reserved ranges when walking through the iomem resources
> with the descriptor 'IORES_DESC_NONE', because several e820 types(
> e.g. E820_TYPE_RESERVED_KERN/E820_TYPE_RAM/E820_TYPE_UNUSABLE/E820
> _TYPE_RESERVED) are converted to the descriptor 'IORES_DESC_NONE'. It
> may pass these four types to the kdump kernel, that is not desired result.
> 
> So, this patch adds a new I/O resource descriptor 'IORES_DESC_RESERVED'
> for the iomem resources search interfaces. It is helpful to exactly
> match the reserved resource ranges when walking through iomem resources.
> 
> In addition, since the new descriptor 'IORES_DESC_RESERVED' is introduced,
> these code originally related to the descriptor 'IORES_DESC_NONE' need to
> be updated. Otherwise, it will be easily confused and also cause some
> errors. Because the 'E820_TYPE_RESERVED' type is converted to the new
> descriptor 'IORES_DESC_RESERVED' instead of 'IORES_DESC_NONE', it has been
> changed.
> 
> Suggested-by: Dave Young <dyoung@redhat.com>
> Signed-off-by: Lianbo Jiang <lijiang@redhat.com>
> ---
>  arch/ia64/kernel/efi.c |  4 ++++
>  arch/x86/kernel/e820.c |  2 +-
>  arch/x86/mm/ioremap.c  | 13 ++++++++++++-
>  include/linux/ioport.h |  1 +
>  kernel/resource.c      |  6 +++---
>  5 files changed, 21 insertions(+), 5 deletions(-)
> 
> diff --git a/arch/ia64/kernel/efi.c b/arch/ia64/kernel/efi.c
> index 8f106638913c..1841e9b4db30 100644
> --- a/arch/ia64/kernel/efi.c
> +++ b/arch/ia64/kernel/efi.c
> @@ -1231,6 +1231,10 @@ efi_initialize_iomem_resources(struct resource *code_resource,
>  				break;
>  
>  			case EFI_RESERVED_TYPE:
> +				name = "reserved";

Ingo updated X86 code to use "Reserved",  I think it would be good to do
same for this case as well

> +				desc = IORES_DESC_RESERVED;
> +				break;
> +
>  			case EFI_RUNTIME_SERVICES_CODE:
>  			case EFI_RUNTIME_SERVICES_DATA:
>  			case EFI_ACPI_RECLAIM_MEMORY:

Originally, above 3 are all "reserved", so probably they all should be
IORES_DESC_RESERVED.

Can any IA64 people to review this?

> diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c
> index 50895c2f937d..57fafdafb860 100644
> --- a/arch/x86/kernel/e820.c
> +++ b/arch/x86/kernel/e820.c
> @@ -1048,10 +1048,10 @@ static unsigned long __init e820_type_to_iores_desc(struct e820_entry *entry)
>  	case E820_TYPE_NVS:		return IORES_DESC_ACPI_NV_STORAGE;
>  	case E820_TYPE_PMEM:		return IORES_DESC_PERSISTENT_MEMORY;
>  	case E820_TYPE_PRAM:		return IORES_DESC_PERSISTENT_MEMORY_LEGACY;
> +	case E820_TYPE_RESERVED:	return IORES_DESC_RESERVED;
>  	case E820_TYPE_RESERVED_KERN:	/* Fall-through: */
>  	case E820_TYPE_RAM:		/* Fall-through: */
>  	case E820_TYPE_UNUSABLE:	/* Fall-through: */
> -	case E820_TYPE_RESERVED:	/* Fall-through: */
>  	default:			return IORES_DESC_NONE;
>  	}
>  }
> diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
> index 5378d10f1d31..fea2ef99415d 100644
> --- a/arch/x86/mm/ioremap.c
> +++ b/arch/x86/mm/ioremap.c
> @@ -83,7 +83,18 @@ static bool __ioremap_check_ram(struct resource *res)
>  
>  static int __ioremap_check_desc_other(struct resource *res)
>  {
> -	return (res->desc != IORES_DESC_NONE);
> +	/*
> +	 * But now, the 'E820_TYPE_RESERVED' type is converted to the new
> +	 * descriptor 'IORES_DESC_RESERVED' instead of 'IORES_DESC_NONE',
> +	 * it has been changed. And the value of 'mem_flags.desc_other'
> +	 * is equal to 'true' if we don't strengthen the condition in this
> +	 * function, that is wrong. Because originally it is equal to
> +	 * 'false' for the same reserved type.
> +	 *
> +	 * So, that would be nice to keep it the same as before.
> +	 */
> +	return ((res->desc != IORES_DESC_NONE) &&
> +		(res->desc != IORES_DESC_RESERVED));
>  }

Added Tom since he added the check function.  Is it possible to only
check explict valid desc types instead of exclude IORES_DESC_NONE?

>  
>  static int __ioremap_res_check(struct resource *res, void *arg)
> diff --git a/include/linux/ioport.h b/include/linux/ioport.h
> index da0ebaec25f0..6ed59de48bd5 100644
> --- a/include/linux/ioport.h
> +++ b/include/linux/ioport.h
> @@ -133,6 +133,7 @@ enum {
>  	IORES_DESC_PERSISTENT_MEMORY_LEGACY	= 5,
>  	IORES_DESC_DEVICE_PRIVATE_MEMORY	= 6,
>  	IORES_DESC_DEVICE_PUBLIC_MEMORY		= 7,
> +	IORES_DESC_RESERVED			= 8,
>  };
>  
>  /* helpers to define resources */
> diff --git a/kernel/resource.c b/kernel/resource.c
> index b0fbf685c77a..f34a632c4169 100644
> --- a/kernel/resource.c
> +++ b/kernel/resource.c
> @@ -994,7 +994,7 @@ __reserve_region_with_split(struct resource *root, resource_size_t start,
>  	res->start = start;
>  	res->end = end;
>  	res->flags = type | IORESOURCE_BUSY;
> -	res->desc = IORES_DESC_NONE;
> +	res->desc = IORES_DESC_RESERVED;
>  
>  	while (1) {
>  
> @@ -1029,7 +1029,7 @@ __reserve_region_with_split(struct resource *root, resource_size_t start,
>  				next_res->start = conflict->end + 1;
>  				next_res->end = end;
>  				next_res->flags = type | IORESOURCE_BUSY;
> -				next_res->desc = IORES_DESC_NONE;
> +				next_res->desc = IORES_DESC_RESERVED;
>  			}
>  		} else {
>  			res->start = conflict->end + 1;
> @@ -1477,7 +1477,7 @@ static int __init reserve_setup(char *str)
>  			res->start = io_start;
>  			res->end = io_start + io_num - 1;
>  			res->flags |= IORESOURCE_BUSY;
> -			res->desc = IORES_DESC_NONE;
> +			res->desc = IORES_DESC_RESERVED;
>  			res->child = NULL;
>  			if (request_resource(parent, res) == 0)
>  				reserved = x+1;
> -- 
> 2.17.1
> 


There are a lot of places call region_intersects which use DESC_NONE,
I'm not sure if needed changes accordingly.  Cced Dan and Toshi.


Thanks
Dave