On Wed, Feb 22, 2012 at 7:32 PM, H. Peter Anvin <hpa@xxxxxxxxx> wrote:
> On 02/22/2012 06:20 PM, Yinghai Lu wrote:
>>
>> Why is MAXMEM used here?
>>
>> EFI reserved area could be above 4G?
>>
>> if that is the case, you will map all mmio hole below 4g.
>>
>
> OK, dropping this patch for now, at least from -urgent.
>
> We really need to restrict the memory types we map, at least without
> ioremap() called on them. In theory, on x86-64, we could have a
> dedicated "1:1" address for each physical address, but there is no good
> reason we should ever map memory types other than RAM, ACPI and EFI by
> default -- with the possible exception of the low 1 MiB legacy area.
please check attach patch for tip/efi branch.
Thanks
Yinghai
Subject: [PATCH] x86, efi: use e820_end_pfn_efi with low_pfn and max_pfn
From: Yinghai Lu <yinghai@xxxxxxxxxx>
So avoid to map mmio below 4g, if system have EFI range above 4g.
Signed-off-by: Yinghai Lu <yinghai@xxxxxxxxxx>
---
arch/x86/kernel/setup.c | 42 ++++++++++++++++++++++++------------------
1 file changed, 24 insertions(+), 18 deletions(-)
Index: linux-2.6/arch/x86/kernel/setup.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/setup.c
+++ linux-2.6/arch/x86/kernel/setup.c
@@ -681,6 +681,27 @@ static int __init parse_reservelow(char
early_param("reservelow", parse_reservelow);
+static unsigned long __init e820_end_pfn_efi(unsigned long end_pfn,
+ unsigned long limit_pfn)
+{
+#ifdef CONFIG_X86_64
+ /*
+ * There may be regions after the last E820_RAM region that we
+ * want to include in the kernel direct mapping because their
+ * contents are needed at runtime.
+ */
+ if (efi_enabled) {
+ unsigned long efi_end;
+
+ efi_end = e820_end_pfn(limit_pfn, E820_RESERVED_EFI);
+ if (efi_end > end_pfn)
+ end_pfn = efi_end;
+ }
+#endif
+
+ return end_pfn;
+}
+
/*
* Determine if we were loaded by an EFI loader. If so, then we have also been
* passed the efi memmap, systab, etc., so we should use these data structures
@@ -934,30 +955,15 @@ void __init setup_arch(char **cmdline_p)
init_gbpages();
/* max_pfn_mapped is updated here */
- end_pfn = max_low_pfn;
-
-#ifdef CONFIG_X86_64
- /*
- * There may be regions after the last E820_RAM region that we
- * want to include in the kernel direct mapping because their
- * contents are needed at runtime.
- */
- if (efi_enabled) {
- unsigned long efi_end;
-
- efi_end = e820_end_pfn(MAXMEM>>PAGE_SHIFT, E820_RESERVED_EFI);
- if (efi_end > end_pfn)
- end_pfn = efi_end;
- }
-#endif
-
+ end_pfn = e820_end_pfn_efi(max_low_pfn, 1UL<<(32-PAGE_SHIFT));
max_low_pfn_mapped = init_memory_mapping(0, end_pfn << PAGE_SHIFT);
max_pfn_mapped = max_low_pfn_mapped;
#ifdef CONFIG_X86_64
if (max_pfn > max_low_pfn) {
+ end_pfn = e820_end_pfn_efi(max_pfn, MAXMEM>>PAGE_SHIFT);
max_pfn_mapped = init_memory_mapping(1UL<<32,
- max_pfn<<PAGE_SHIFT);
+ end_pfn<<PAGE_SHIFT);
/* can we preseve max_low_pfn ?*/
max_low_pfn = max_pfn;
}
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