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.d...@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyng...@arm.com>
---
arch/arm/include/asm/kvm_mmu.h | 3 ++-
arch/arm/kvm/mmu.c | 8 ++++----
arch/arm64/include/asm/kvm_mmu.h | 2 ++
3 files changed, 8 insertions(+), 5 deletions(-)
diff --git a/arch/arm/include/asm/kvm_mmu.h b/arch/arm/include/asm/kvm_mmu.h
index ff56f91..9486a7a 100644
--- a/arch/arm/include/asm/kvm_mmu.h
+++ b/arch/arm/include/asm/kvm_mmu.h
@@ -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)
diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c
index 0a5457c..f99543d 100644
--- a/arch/arm/kvm/mmu.c
+++ b/arch/arm/kvm/mmu.c
@@ -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);
@@ -844,7 +844,7 @@ 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;
@@ -1134,7 +1134,7 @@ 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
diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h
index 8354152..d8f809f 100644
--- a/arch/arm64/include/asm/kvm_mmu.h
+++ b/arch/arm64/include/asm/kvm_mmu.h
@@ -160,6 +160,8 @@ 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
--
2.1.4
_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
