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kvm, x86: Properly check whether a pfn is an MMIO or not

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pfn_valid check is not sufficient because it only checks if a page has a struct
page or not, if "mem=" was passed to the kernel some valid pages won't have a
struct page. This means that if guests were assigned valid memory that lies
after the mem= boundary it will be passed uncached to the guest no matter what
the guest caching attributes are for this memory.

Introduce a new function e820__mapped_raw_any which is equivalent to
e820__mapped_any but uses the original e820 unmodified and use it to
identify real *RAM*.

Signed-off-by: KarimAllah Ahmed <karahmed@amazon.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
KarimAllah Ahmed 2019-01-31 21:24:44 +01:00 committed by Paolo Bonzini
parent e0bf2665ca
commit 0c55671f84
3 changed files with 20 additions and 4 deletions
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1
arch/x86/include/asm/e820/api.h
View File

@ -10,6 +10,7 @@ extern struct e820_table *e820_table_firmware;
extern unsigned long pci_mem_start;
extern bool e820__mapped_raw_any(u64 start, u64 end, enum e820_type type);
extern bool e820__mapped_any(u64 start, u64 end, enum e820_type type);
extern bool e820__mapped_all(u64 start, u64 end, enum e820_type type);

18
arch/x86/kernel/e820.c
View File

@ -73,12 +73,13 @@ EXPORT_SYMBOL(pci_mem_start);
* This function checks if any part of the range <start,end> is mapped
* with type.
*/
bool e820__mapped_any(u64 start, u64 end, enum e820_type type)
static bool _e820__mapped_any(struct e820_table *table,
u64 start, u64 end, enum e820_type type)
{
int i;
for (i = 0; i < e820_table->nr_entries; i++) {
struct e820_entry *entry = &e820_table->entries[i];
for (i = 0; i < table->nr_entries; i++) {
struct e820_entry *entry = &table->entries[i];
if (type && entry->type != type)
continue;
@ -88,6 +89,17 @@ bool e820__mapped_any(u64 start, u64 end, enum e820_type type)
}
return 0;
}
bool e820__mapped_raw_any(u64 start, u64 end, enum e820_type type)
{
return _e820__mapped_any(e820_table_firmware, start, end, type);
}
EXPORT_SYMBOL_GPL(e820__mapped_raw_any);
bool e820__mapped_any(u64 start, u64 end, enum e820_type type)
{
return _e820__mapped_any(e820_table, start, end, type);
}
EXPORT_SYMBOL_GPL(e820__mapped_any);
/*

5
arch/x86/kvm/mmu.c
View File

@ -44,6 +44,7 @@
#include <asm/page.h>
#include <asm/pat.h>
#include <asm/cmpxchg.h>
#include <asm/e820/api.h>
#include <asm/io.h>
#include <asm/vmx.h>
#include <asm/kvm_page_track.h>
@ -2892,7 +2893,9 @@ static bool kvm_is_mmio_pfn(kvm_pfn_t pfn)
*/
(!pat_enabled() || pat_pfn_immune_to_uc_mtrr(pfn));
return true;
return !e820__mapped_raw_any(pfn_to_hpa(pfn),
pfn_to_hpa(pfn + 1) - 1,
E820_TYPE_RAM);
}
/* Bits which may be returned by set_spte() */