From: Takuya Yoshikawa <[email protected]>

Int is not long enough to store the size of a dirty bitmap.

This patch fixes this problem with the introduction of a wrapper
function to calculate the sizes of dirty bitmaps.

Note: in mark_page_dirty(), we have to consider the fact that
  __set_bit() takes the offset as int, not long.

Signed-off-by: Takuya Yoshikawa <[email protected]>
Signed-off-by: Marcelo Tosatti <[email protected]>

diff --git a/arch/ia64/kvm/kvm-ia64.c b/arch/ia64/kvm/kvm-ia64.c
index b0ed80c..566aff6 100644
--- a/arch/ia64/kvm/kvm-ia64.c
+++ b/arch/ia64/kvm/kvm-ia64.c
@@ -1806,7 +1806,8 @@ static int kvm_ia64_sync_dirty_log(struct kvm *kvm,
 {
        struct kvm_memory_slot *memslot;
        int r, i;
-       long n, base;
+       long base;
+       unsigned long n;
        unsigned long *dirty_bitmap = (unsigned long *)(kvm->arch.vm_base +
                        offsetof(struct kvm_vm_data, kvm_mem_dirty_log));
 
@@ -1819,7 +1820,7 @@ static int kvm_ia64_sync_dirty_log(struct kvm *kvm,
        if (!memslot->dirty_bitmap)
                goto out;
 
-       n = ALIGN(memslot->npages, BITS_PER_LONG) / 8;
+       n = kvm_dirty_bitmap_bytes(memslot);
        base = memslot->base_gfn / BITS_PER_LONG;
 
        for (i = 0; i < n/sizeof(long); ++i) {
@@ -1835,7 +1836,7 @@ int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm,
                struct kvm_dirty_log *log)
 {
        int r;
-       int n;
+       unsigned long n;
        struct kvm_memory_slot *memslot;
        int is_dirty = 0;
 
@@ -1854,7 +1855,7 @@ int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm,
        if (is_dirty) {
                kvm_flush_remote_tlbs(kvm);
                memslot = &kvm->memslots->memslots[log->slot];
-               n = ALIGN(memslot->npages, BITS_PER_LONG) / 8;
+               n = kvm_dirty_bitmap_bytes(memslot);
                memset(memslot->dirty_bitmap, 0, n);
        }
        r = 0;
diff --git a/arch/powerpc/kvm/book3s.c b/arch/powerpc/kvm/book3s.c
index a7ab2ea..4ac7b15 100644
--- a/arch/powerpc/kvm/book3s.c
+++ b/arch/powerpc/kvm/book3s.c
@@ -1118,7 +1118,8 @@ int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm,
        struct kvm_vcpu *vcpu;
        ulong ga, ga_end;
        int is_dirty = 0;
-       int r, n;
+       int r;
+       unsigned long n;
 
        mutex_lock(&kvm->slots_lock);
 
@@ -1136,7 +1137,7 @@ int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm,
                kvm_for_each_vcpu(n, vcpu, kvm)
                        kvmppc_mmu_pte_pflush(vcpu, ga, ga_end);
 
-               n = ALIGN(memslot->npages, BITS_PER_LONG) / 8;
+               n = kvm_dirty_bitmap_bytes(memslot);
                memset(memslot->dirty_bitmap, 0, n);
        }
 
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index f3662ad..bffd049 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2648,8 +2648,9 @@ static int kvm_vm_ioctl_reinject(struct kvm *kvm,
 int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm,
                                      struct kvm_dirty_log *log)
 {
-       int r, n, i;
+       int r, i;
        struct kvm_memory_slot *memslot;
+       unsigned long n;
        unsigned long is_dirty = 0;
        unsigned long *dirty_bitmap = NULL;
 
@@ -2664,7 +2665,7 @@ int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm,
        if (!memslot->dirty_bitmap)
                goto out;
 
-       n = ALIGN(memslot->npages, BITS_PER_LONG) / 8;
+       n = kvm_dirty_bitmap_bytes(memslot);
 
        r = -ENOMEM;
        dirty_bitmap = vmalloc(n);
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 8e91fa7..169d077 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -119,6 +119,11 @@ struct kvm_memory_slot {
        int user_alloc;
 };
 
+static inline unsigned long kvm_dirty_bitmap_bytes(struct kvm_memory_slot 
*memslot)
+{
+       return ALIGN(memslot->npages, BITS_PER_LONG) / 8;
+}
+
 struct kvm_kernel_irq_routing_entry {
        u32 gsi;
        u32 type;
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 9379533..6fe79c4 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -645,7 +645,7 @@ skip_lpage:
 
        /* Allocate page dirty bitmap if needed */
        if ((new.flags & KVM_MEM_LOG_DIRTY_PAGES) && !new.dirty_bitmap) {
-               unsigned dirty_bytes = ALIGN(npages, BITS_PER_LONG) / 8;
+               unsigned long dirty_bytes = kvm_dirty_bitmap_bytes(&new);
 
                new.dirty_bitmap = vmalloc(dirty_bytes);
                if (!new.dirty_bitmap)
@@ -765,7 +765,7 @@ int kvm_get_dirty_log(struct kvm *kvm,
 {
        struct kvm_memory_slot *memslot;
        int r, i;
-       int n;
+       unsigned long n;
        unsigned long any = 0;
 
        r = -EINVAL;
@@ -777,7 +777,7 @@ int kvm_get_dirty_log(struct kvm *kvm,
        if (!memslot->dirty_bitmap)
                goto out;
 
-       n = ALIGN(memslot->npages, BITS_PER_LONG) / 8;
+       n = kvm_dirty_bitmap_bytes(memslot);
 
        for (i = 0; !any && i < n/sizeof(long); ++i)
                any = memslot->dirty_bitmap[i];
@@ -1183,10 +1183,13 @@ void mark_page_dirty(struct kvm *kvm, gfn_t gfn)
        memslot = gfn_to_memslot_unaliased(kvm, gfn);
        if (memslot && memslot->dirty_bitmap) {
                unsigned long rel_gfn = gfn - memslot->base_gfn;
+               unsigned long *p = memslot->dirty_bitmap +
+                                       rel_gfn / BITS_PER_LONG;
+               int offset = rel_gfn % BITS_PER_LONG;
 
                /* avoid RMW */
-               if (!generic_test_le_bit(rel_gfn, memslot->dirty_bitmap))
-                       generic___set_le_bit(rel_gfn, memslot->dirty_bitmap);
+               if (!generic_test_le_bit(offset, p))
+                       generic___set_le_bit(offset, p);
        }
 }
 
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