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Commit 0c55671f authored by KarimAllah Ahmed's avatar KarimAllah Ahmed Committed by Paolo Bonzini
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kvm, x86: Properly check whether a pfn is an MMIO or not 



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: default avatarKarimAllah Ahmed <karahmed@amazon.de>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent e0bf2665

arch/x86/include/asm/e820/api.h

+1 −0
Original line number Diff line number Diff line
@@ -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);

arch/x86/kernel/e820.c

+15 −3
Original line number Diff line number Diff line
@@ -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);



/*

arch/x86/kvm/mmu.c

+4 −1
Original line number Diff line number Diff line
@@ -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() */