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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>
Cc:     Dave Young <dyoung@redhat.com>,
        "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>
 <95661569-d9c9-af13-11c4-c0d752710a1f@redhat.com>
 <b1556461-fe83-2ba0-00a3-e8ecf3e286fe@amd.com>
From:   lijiang <lijiang@redhat.com>
Message-ID: <2b721ccb-278a-5934-c7a1-e1f62ab5efa5@redhat.com>
Date:   Tue, 26 Mar 2019 17:52:17 +0800
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在 2019年03月26日 03:34, Lendacky, Thomas 写道:
> On 3/16/19 2:31 AM, lijiang wrote:
>>
>>
>> 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.
>>
>> Recently, i tested it according to your advice, here it is really checking for the
>> 'IORES_DESC_ACPI_*' values.  If you agree to this change, i would add the following
>> patch into this patch set and post them again.
>>
>> [root@localhost linux]# git diff arch/x86/mm/ioremap.c
>> diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
>> index 0029604af8a4..0e3ba620612d 100644
>> --- a/arch/x86/mm/ioremap.c
>> +++ b/arch/x86/mm/ioremap.c
>> @@ -83,7 +83,8 @@ static bool __ioremap_check_ram(struct resource *res)
>>  
>>  static int __ioremap_check_desc_other(struct resource *res)
>>  {
>> -       return (res->desc != IORES_DESC_NONE);
>> +       return ((res->desc == IORES_DESC_ACPI_TABLES) ||
>> +               (res->desc == IORES_DESC_ACPI_NV_STORAGE));
> 
> I'm not a big fan of this. I think you should leave it as the previous
> check you had for IORES_DESC_NONE and IORES_DESC_RESERVED. There's no
> telling what type of resources may be mapped in the future where this
> will break.
> 
> Adding a nice comment here about how IORES_DESC_NONE originally was to
> identify MMIO and reserved areas. Now IORES_DESC_RESERVED has been created
> for the reserved areas so the check needs to be expanded so that these
> areas aren't mapped encrypted when using ioremap.

Thanks for your comment.

It's OK for me. I'm not sure whether Boris has any suggestion.

Thanks.
Lianbo

> 
> Thanks,
> Tom
> 
>>  }
>>
>>
>> Thanks.
>> 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
>>>>