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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: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
This commit is contained in:
Marc Zyngier 2015-03-10 19:07:00 +00:00 committed by Christoffer Dall
parent a987370f8e
commit 04b8dc85bf
3 changed files with 8 additions and 5 deletions
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3
arch/arm/include/asm/kvm_mmu.h
View File

@ -149,13 +149,14 @@ static inline bool kvm_s2pmd_readonly(pmd_t *pmd)
(__boundary - 1 < (end) - 1)? __boundary: (end); \ (__boundary - 1 < (end) - 1)? __boundary: (end); \
}) })
#define kvm_pgd_index(addr) pgd_index(addr)
static inline bool kvm_page_empty(void *ptr) static inline bool kvm_page_empty(void *ptr)
{ {
struct page *ptr_page = virt_to_page(ptr); struct page *ptr_page = virt_to_page(ptr);
return page_count(ptr_page) == 1; return page_count(ptr_page) == 1;
} }
#define kvm_pte_table_empty(kvm, ptep) kvm_page_empty(ptep) #define kvm_pte_table_empty(kvm, ptep) kvm_page_empty(ptep)
#define kvm_pmd_table_empty(kvm, pmdp) kvm_page_empty(pmdp) #define kvm_pmd_table_empty(kvm, pmdp) kvm_page_empty(pmdp)
#define kvm_pud_table_empty(kvm, pudp) (0) #define kvm_pud_table_empty(kvm, pudp) (0)

8
arch/arm/kvm/mmu.c
View File

@ -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 addr = start, end = start + size;
phys_addr_t next; phys_addr_t next;
pgd = pgdp + pgd_index(addr); pgd = pgdp + kvm_pgd_index(addr);
do { do {
next = kvm_pgd_addr_end(addr, end); next = kvm_pgd_addr_end(addr, end);
if (!pgd_none(*pgd)) if (!pgd_none(*pgd))
@ -355,7 +355,7 @@ static void stage2_flush_memslot(struct kvm *kvm,
phys_addr_t next; phys_addr_t next;
pgd_t *pgd; pgd_t *pgd;
pgd = kvm->arch.pgd + pgd_index(addr); pgd = kvm->arch.pgd + kvm_pgd_index(addr);
do { do {
next = kvm_pgd_addr_end(addr, end); next = kvm_pgd_addr_end(addr, end);
stage2_flush_puds(kvm, pgd, addr, next); 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; pgd_t *pgd;
pud_t *pud; 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 (WARN_ON(pgd_none(*pgd))) {
if (!cache) if (!cache)
return NULL; 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; pgd_t *pgd;
phys_addr_t next; phys_addr_t next;
pgd = kvm->arch.pgd + pgd_index(addr); pgd = kvm->arch.pgd + kvm_pgd_index(addr);
do { do {
/* /*
* Release kvm_mmu_lock periodically if the memory region is * Release kvm_mmu_lock periodically if the memory region is

2
arch/arm64/include/asm/kvm_mmu.h
View File

@ -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 PTRS_PER_S2_PGD (1 << PTRS_PER_S2_PGD_SHIFT)
#define S2_PGD_ORDER get_order(PTRS_PER_S2_PGD * sizeof(pgd_t)) #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 * 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 * than or equal to 16 pointers in the fake PGD, because that's what the