Re: [PATCH 1/2 v8] resource: add the new I/O resource descriptor 'IORES_DESC_RESERVED'
From: Dave Young
Date: Thu Nov 29 2018 - 22:49:15 EST
Correct Toshi's email addr
On 11/30/18 at 11:37am, 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@xxxxxxxxxx>
> > Signed-off-by: Lianbo Jiang <lijiang@xxxxxxxxxx>
> > ---
> > 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