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Subject: Re: [PATCH 1/2 v8] resource: add the new I/O resource descriptor
 'IORES_DESC_RESERVED'
To:     "Lendacky, Thomas" <Thomas.Lendacky@amd.com>,
        Dave Young <dyoung@redhat.com>
Cc:     "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "kexec@lists.infradead.org" <kexec@lists.infradead.org>,
        "x86@kernel.org" <x86@kernel.org>,
        "linux-ia64@vger.kernel.org" <linux-ia64@vger.kernel.org>,
        "linux-efi@vger.kernel.org" <linux-efi@vger.kernel.org>,
        "tglx@linutronix.de" <tglx@linutronix.de>,
        "mingo@redhat.com" <mingo@redhat.com>,
        "bp@alien8.de" <bp@alien8.de>,
        "akpm@linux-foundation.org" <akpm@linux-foundation.org>,
        "dave.hansen@linux.intel.com" <dave.hansen@linux.intel.com>,
        "luto@kernel.org" <luto@kernel.org>,
        "peterz@infradead.org" <peterz@infradead.org>,
        "ard.biesheuvel@linaro.org" <ard.biesheuvel@linaro.org>,
        "tony.luck@intel.com" <tony.luck@intel.com>,
        "fenghua.yu@intel.com" <fenghua.yu@intel.com>,
        "bhe@redhat.com" <bhe@redhat.com>, Toshi Kani <toshi.kani@hp.com>,
        Dan Williams <dan.j.williams@intel.com>
References: <20181129080956.20776-1-lijiang@redhat.com>
 <20181129080956.20776-2-lijiang@redhat.com>
 <20181130033703.GA23624@dhcp-128-65.nay.redhat.com>
 <b8936194-01ef-8b8f-254e-039fc951855d@amd.com>
From:   lijiang <lijiang@redhat.com>
Message-ID: <ddc4aae4-72ee-8ceb-d52d-db9f7b9fcab6@redhat.com>
Date:   Wed, 12 Dec 2018 09:55:52 +0800
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在 2018年12月05日 05:33, Lendacky, Thomas 写道:
> 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.
> 
 
I'm looking forward to the result of your test about this change.
Once changed, this patch also needs to be changed accordingly.

Thank you, Tom.

Lianbo
> 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
>>