Re: [PATCH 1/2 v8] resource: add the new I/O resource descriptor 'IORES_DESC_RESERVED'

["Lendacky, Thomas" <Thomas.Lendacky@amd.com>]

On 11/29/2018 09:37 PM, Dave Young wrote:
> + 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?

Sorry for the delay...

The original intent of the check was to map most memory as encrypted under
SEV if it was marked with a specific descriptor, since it was likely to
not be MMIO. I tried converting most things that mapped memory to memremap
vs ioremap, but ACPI was one area that I left alone and this check catches
the mapping of the ACPI tables. I suppose it's possible to change this to
check just for IORES_DESC_ACPI_* values, but I would have to do some
testing.

Thanks,
Tom

> 
>>  
>>  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
>