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Date: Tue, 26 Mar 2019 17:52:17 +0800
From: lijiang <lijiang@...hat.com>
To: "Lendacky, Thomas" <Thomas.Lendacky@....com>
Cc: Dave Young <dyoung@...hat.com>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"kexec@...ts.infradead.org" <kexec@...ts.infradead.org>,
"x86@...nel.org" <x86@...nel.org>,
"linux-ia64@...r.kernel.org" <linux-ia64@...r.kernel.org>,
"linux-efi@...r.kernel.org" <linux-efi@...r.kernel.org>,
"tglx@...utronix.de" <tglx@...utronix.de>,
"mingo@...hat.com" <mingo@...hat.com>,
"bp@...en8.de" <bp@...en8.de>,
"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
"dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>,
"luto@...nel.org" <luto@...nel.org>,
"peterz@...radead.org" <peterz@...radead.org>,
"ard.biesheuvel@...aro.org" <ard.biesheuvel@...aro.org>,
"tony.luck@...el.com" <tony.luck@...el.com>,
"fenghua.yu@...el.com" <fenghua.yu@...el.com>,
"bhe@...hat.com" <bhe@...hat.com>, Toshi Kani <toshi.kani@...com>,
Dan Williams <dan.j.williams@...el.com>
Subject: Re: [PATCH 1/2 v8] resource: add the new I/O resource descriptor
'IORES_DESC_RESERVED'
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@...hat.com>
>>>>> Signed-off-by: Lianbo Jiang <lijiang@...hat.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@...alhost 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
>>>>
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