x86/e820, ioport: Add a new I/O resource descriptor IORES_DESC_RESERVED

When executing the kexec_file_load() syscall, the first kernel needs to
pass the e820 reserved ranges to the second kernel because some devices
(PCI, for example) need them present in the kdump kernel for proper
initialization.

But the kernel can not exactly match the e820 reserved ranges when
walking through the iomem resources using the default IORES_DESC_NONE
descriptor, because there are several types of e820 ranges which are
marked IORES_DESC_NONE, see e820_type_to_iores_desc().

Therefore, add a new I/O resource descriptor called IORES_DESC_RESERVED
to mark exactly those ranges. It will be used to match the reserved
resource ranges when walking through iomem resources.

 [ bp: Massage commit message. ]
Suggested-by: NBorislav Petkov <bp@suse.de>
Signed-off-by: NLianbo Jiang <lijiang@redhat.com>
Signed-off-by: NBorislav Petkov <bp@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: bhe@redhat.com
Cc: dave.hansen@linux.intel.com
Cc: dyoung@redhat.com
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Huang Zijiang <huang.zijiang@zte.com.cn>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Joe Perches <joe@perches.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: kexec@lists.infradead.org
Cc: Masayoshi Mizuma <m.mizuma@jp.fujitsu.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: x86-ml <x86@kernel.org>
Link: https://lkml.kernel.org/r/20190423013007.17838-2-lijiang@redhat.com

arch/x86/kernel/e820.c

@@ -1063,10 +1063,10 @@ 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;
 	}
 }

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 */