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

commit 04b8dc85bf4a64517e3cf20e409eeaa503b15cc1 upstream.

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>
Signed-off-by: Shannon Zhao <shannon.zhao@linaro.org>
[ luis: backported to 3.16: used shannon's backport to 3.14 ]
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

diff --git a/arch/arm/include/asm/kvm_mmu.h b/arch/arm/include/asm/kvm_mmu.h
index c02a8367dee44f601fb8cdee9758e17a4a119084..8618badbbbbeb17506645ba9c37388646bd4cd72 100644 (file)
--- a/arch/arm/include/asm/kvm_mmu.h
+++ b/arch/arm/include/asm/kvm_mmu.h
@@ -117,13 +117,14 @@ static inline void kvm_set_s2pmd_writable(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(ptep) kvm_page_empty(ptep)
 #define kvm_pmd_table_empty(pmdp) kvm_page_empty(pmdp)
 #define kvm_pud_table_empty(pudp) (0)

diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c
index bbf6a127ef3c13665423ecf6c8e5460c4392d207..c65db5d7ea9285c5bdac7c0eb83dcdc608dfe1c7 100644 (file)
--- a/arch/arm/kvm/mmu.c
+++ b/arch/arm/kvm/mmu.c
@@ -194,7 +194,7 @@ 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))
@@ -264,7 +264,7 @@ 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);
@@ -649,7 +649,7 @@ static pmd_t *stage2_get_pmd(struct kvm *kvm, struct kvm_mmu_memory_cache *cache
        pud_t *pud;
        pmd_t *pmd;
 
-       pgd = kvm->arch.pgd + pgd_index(addr);
+       pgd = kvm->arch.pgd + kvm_pgd_index(addr);
        pud = pud_offset(pgd, addr);
        if (pud_none(*pud)) {
                if (!cache)

diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h
index 0d51874c838f42c7afdab5485d3c1a094ef69049..2067f4b75d13900766ceeab0a064509528c1a0a9 100644 (file)
--- a/arch/arm64/include/asm/kvm_mmu.h
+++ b/arch/arm64/include/asm/kvm_mmu.h
@@ -69,6 +69,8 @@
 #define PTRS_PER_S2_PGD (1 << (KVM_PHYS_SHIFT - PGDIR_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))
+
 int create_hyp_mappings(void *from, void *to);
 int create_hyp_io_mappings(void *from, void *to, phys_addr_t);
 void free_boot_hyp_pgd(void);