From: Alexey Kardashevskiy <aik@xxxxxxxxx>
The dirty map that we construct for the KVM_GET_DIRTY_LOG ioctl has
one bit per system page (4K/64K). Currently, we only set one bit in
the map for each HPT entry with the Change bit set, even if the HPT is
for a large page (e.g., 16MB). Userspace then considers only the
first system page dirty, though in fact the guest may have modified
anywhere in the large page.
To fix this, we make kvm_test_clear_dirty() return the actual number
of pages that are dirty. In kvmppc_hv_get_dirty_log() we then set
that many bits in the dirty map.
Signed-off-by: Alexey Kardashevskiy <aik@xxxxxxxxx>
Signed-off-by: Paul Mackerras <paulus@xxxxxxxxx>
---
arch/powerpc/kvm/book3s_64_mmu_hv.c | 14 ++++++++++----
1 file changed, 10 insertions(+), 4 deletions(-)
diff --git a/arch/powerpc/kvm/book3s_64_mmu_hv.c b/arch/powerpc/kvm/book3s_64_mmu_hv.c
index f32896f..d605dc24 100644
--- a/arch/powerpc/kvm/book3s_64_mmu_hv.c
+++ b/arch/powerpc/kvm/book3s_64_mmu_hv.c
@@ -1053,6 +1053,7 @@ static int kvm_test_clear_dirty(struct kvm *kvm, unsigned long *rmapp)
{
struct revmap_entry *rev = kvm->arch.revmap;
unsigned long head, i, j;
+ unsigned long n;
unsigned long *hptep;
int ret = 0;
@@ -1095,7 +1096,10 @@ static int kvm_test_clear_dirty(struct kvm *kvm, unsigned long *rmapp)
rev[i].guest_rpte |= HPTE_R_C;
note_hpte_modification(kvm, &rev[i]);
}
- ret = 1;
+ n = hpte_page_size(hptep[0], hptep[1]);
+ n = (n + PAGE_SIZE - 1) >> PAGE_SHIFT;
+ if (n > ret)
+ ret = n;
}
hptep[0] &= ~HPTE_V_HVLOCK;
} while ((i = j) != head);
@@ -1125,15 +1129,17 @@ static void harvest_vpa_dirty(struct kvmppc_vpa *vpa,
long kvmppc_hv_get_dirty_log(struct kvm *kvm, struct kvm_memory_slot *memslot,
unsigned long *map)
{
- unsigned long i;
+ unsigned long i, j;
unsigned long *rmapp;
struct kvm_vcpu *vcpu;
preempt_disable();
rmapp = memslot->arch.rmap;
for (i = 0; i < memslot->npages; ++i) {
- if (kvm_test_clear_dirty(kvm, rmapp) && map)
- __set_bit_le(i, map);
+ int ret = kvm_test_clear_dirty(kvm, rmapp);
+ if (ret && map)
+ for (j = i - (i % ret); ret; ++j, --ret)
+ __set_bit_le(j, map);
++rmapp;
}
--
2.0.0.rc2
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