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Commit 04b8dc85 authored by Marc Zyngier's avatar Marc Zyngier Committed by Christoffer Dall
Browse files

arm64: KVM: Do not use pgd_index to index stage-2 pgd 



The kernel's pgd_index macro is designed to index a normal, page
sized array. KVM is a bit diffferent, as we can use concatenated
pages to have a bigger address space (for example 40bit IPA with
4kB pages gives us an 8kB PGD.

In the above case, the use of pgd_index will always return an index
inside the first 4kB, which makes a guest that has memory above
0x8000000000 rather unhappy, as it spins forever in a page fault,
whist the host happilly corrupts the lower pgd.

The obvious fix is to get our own kvm_pgd_index that does the right
thing(tm).

Tested on X-Gene with a hacked kvmtool that put memory at a stupidly
high address.

Reviewed-by: default avatarChristoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: default avatarChristoffer Dall <christoffer.dall@linaro.org>
parent a987370f

arch/arm/include/asm/kvm_mmu.h

+2 −1
Original line number Diff line number Diff line
@@ -149,13 +149,14 @@ static inline bool kvm_s2pmd_readonly(pmd_t *pmd) 
	(__boundary - 1 < (end) - 1)? __boundary: (end);		\

})



#define kvm_pgd_index(addr)			pgd_index(addr)



static inline bool kvm_page_empty(void *ptr)

{

	struct page *ptr_page = virt_to_page(ptr);

	return page_count(ptr_page) == 1;

}





#define kvm_pte_table_empty(kvm, ptep) kvm_page_empty(ptep)

#define kvm_pmd_table_empty(kvm, pmdp) kvm_page_empty(pmdp)

#define kvm_pud_table_empty(kvm, pudp) (0)

arch/arm/kvm/mmu.c

+4 −4
Original line number Diff line number Diff line
@@ -290,7 +290,7 @@ static void unmap_range(struct kvm *kvm, pgd_t *pgdp, 
	phys_addr_t addr = start, end = start + size;

	phys_addr_t next;



	pgd = pgdp + pgd_index(addr);

	pgd = pgdp + kvm_pgd_index(addr);

	do {

		next = kvm_pgd_addr_end(addr, end);

		if (!pgd_none(*pgd))
@@ -355,7 +355,7 @@ static void stage2_flush_memslot(struct kvm *kvm, 
	phys_addr_t next;

	pgd_t *pgd;



	pgd = kvm->arch.pgd + pgd_index(addr);

	pgd = kvm->arch.pgd + kvm_pgd_index(addr);

	do {

		next = kvm_pgd_addr_end(addr, end);

		stage2_flush_puds(kvm, pgd, addr, next);
@@ -830,7 +830,7 @@ static pud_t *stage2_get_pud(struct kvm *kvm, struct kvm_mmu_memory_cache *cache 
	pgd_t *pgd;

	pud_t *pud;



	pgd = kvm->arch.pgd + pgd_index(addr);

	pgd = kvm->arch.pgd + kvm_pgd_index(addr);

	if (WARN_ON(pgd_none(*pgd))) {

		if (!cache)

			return NULL;
@@ -1120,7 +1120,7 @@ static void stage2_wp_range(struct kvm *kvm, phys_addr_t addr, phys_addr_t end) 
	pgd_t *pgd;

	phys_addr_t next;



	pgd = kvm->arch.pgd + pgd_index(addr);

	pgd = kvm->arch.pgd + kvm_pgd_index(addr);

	do {

		/*

		 * Release kvm_mmu_lock periodically if the memory region is

arch/arm64/include/asm/kvm_mmu.h

+2 −0
Original line number Diff line number Diff line
@@ -158,6 +158,8 @@ static inline bool kvm_s2pmd_readonly(pmd_t *pmd) 
#define PTRS_PER_S2_PGD		(1 << PTRS_PER_S2_PGD_SHIFT)

#define S2_PGD_ORDER		get_order(PTRS_PER_S2_PGD * sizeof(pgd_t))



#define kvm_pgd_index(addr)	(((addr) >> PGDIR_SHIFT) & (PTRS_PER_S2_PGD - 1))



/*

 * If we are concatenating first level stage-2 page tables, we would have less

 * than or equal to 16 pointers in the fake PGD, because that's what the