Add support for dirty bitmap management. Wanted to make it generic but function
does a couple things different then the x86 version.
Signed-off-by: Mario Smarduch <m.smarduch@xxxxxxxxxxx>
---
arch/arm/include/asm/kvm_host.h | 3 ++
arch/arm/kvm/arm.c | 71 ++++++++++++++++++++++++++++++++++++++-
arch/arm/kvm/mmu.c | 53 +++++++++++++++++++++++++++++
3 files changed, 126 insertions(+), 1 deletion(-)
diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h
index 7ac1fdc..16ed4e4 100644
--- a/arch/arm/include/asm/kvm_host.h
+++ b/arch/arm/include/asm/kvm_host.h
@@ -230,5 +230,8 @@ int kvm_arm_timer_set_reg(struct kvm_vcpu *, u64 regid, u64 value);
void kvm_tlb_flush_vm(struct kvm *kvm);
void kvm_mmu_slot_remove_write_access(struct kvm *kvm, int slot);
+void kvm_mmu_write_protect_pt_masked(struct kvm *kvm,
+ struct kvm_memory_slot *slot,
+ gfn_t gfn_offset, unsigned long mask);
#endif /* __ARM_KVM_HOST_H__ */
diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
index 7714cc6..7882343 100644
--- a/arch/arm/kvm/arm.c
+++ b/arch/arm/kvm/arm.c
@@ -785,9 +785,78 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
}
}
+
+/**
+ * kvm_mmu_slot_remove_access - retrieves the log of dirty pages for a memslot.
+ * It's itteratively during migration to retrieve pages written since
+ * last call. In the process write protects ptes that are dirty for next
+ * time, holds the mmu_lock while write protecting dirty pages.
+ *
+ * @kvm: The KVM pointer
+ * @log: Bitmap of dirty pages return.
+ */
int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, struct kvm_dirty_log *log)
{
- return -EINVAL;
+ int r;
+ struct kvm_memory_slot *memslot;
+ unsigned long n, i;
+ unsigned long *dirty_bitmap;
+ unsigned long *dirty_bitmap_buffer;
+ bool is_dirty = false;
+ gfn_t offset;
+
+ mutex_lock(&kvm->slots_lock);
+ r = -EINVAL;
+
+ /* Return with error code will cause migration to abort, this happens
+ * when initial write protection of VM to manage dirty pages fails
+ */
+ if (kvm->arch.migration_in_progress == -1)
+ goto out;
+
+ if (log->slot >= KVM_USER_MEM_SLOTS)
+ goto out;
+
+ memslot = id_to_memslot(kvm->memslots, log->slot);
+ dirty_bitmap = memslot->dirty_bitmap;
+
+ r = -ENOENT;
+ if (!dirty_bitmap)
+ goto out;
+
+ n = kvm_dirty_bitmap_bytes(memslot);
+ dirty_bitmap_buffer = dirty_bitmap + n / sizeof(long);
+ memset(dirty_bitmap_buffer, 0, n);
+
+ spin_lock(&kvm->mmu_lock);
+ for (i = 0; i < n / sizeof(long); i++) {
+ unsigned long mask;
+
+ if (!dirty_bitmap[i])
+ continue;
+
+ is_dirty = true;
+ offset = i * BITS_PER_LONG;
+ kvm_mmu_write_protect_pt_masked(kvm, memslot, offset,
+ dirty_bitmap[i]);
+ mask = dirty_bitmap[i];
+ dirty_bitmap_buffer[i] = mask;
+ dirty_bitmap[i] = 0;
+ }
+
+ if (is_dirty)
+ kvm_tlb_flush_vm(kvm);
+
+ spin_unlock(&kvm->mmu_lock);
+ r = -EFAULT;
+
+ if (copy_to_user(log->dirty_bitmap, dirty_bitmap_buffer, n))
+ goto out;
+
+ r = 0;
+out:
+ mutex_unlock(&kvm->slots_lock);
+ return r;
}
static int kvm_vm_ioctl_set_device_addr(struct kvm *kvm,
diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c
index b85ab56..47bec1c 100644
--- a/arch/arm/kvm/mmu.c
+++ b/arch/arm/kvm/mmu.c
@@ -773,6 +773,59 @@ void kvm_mmu_slot_remove_write_access(struct kvm *kvm, int slot)
spin_unlock(&kvm->mmu_lock);
}
+
+/**
+ * kvm_mmu_write_protected_pt_masked - after migration thread write protects
+ * the entire VM address space itterative calls are made to get diry pages
+ * as the VM pages are being migrated. New dirty pages may be subset
+ * of initial WPed VM or new writes faulted in. Here write protect new
+ * dirty pages again in preparation of next dirty log read. This function is
+ * called as a result KVM_GET_DIRTY_LOG ioctl, to determine what pages
+ * need to be migrated.
+ * 'kvm->mmu_lock' must be held to protect against concurrent modification
+ * of page tables (2nd stage fault, mmu modifiers, device writes)
+ *
+ * @kvm: The KVM pointer
+ * @slot: The memory slot the dirty log is retrieved for
+ * @gfn_offset: The gfn offset in memory slot
+ * @mask: The mask of dirty pages at offset 'gnf_offset in this memory
+ * slot to be writ protect
+ */
+
+void kvm_mmu_write_protect_pt_masked(struct kvm *kvm,
+ struct kvm_memory_slot *slot,
+ gfn_t gfn_offset, unsigned long mask)
+{
+ phys_addr_t ipa;
+ pgd_t *pgdp = kvm->arch.pgd, *pgd;
+ pud_t *pud;
+ pmd_t *pmd;
+ pte_t *pte, new_pte;
+
+ /* walk set bits in the mask and write protect corresponding pages */
+ while (mask) {
+ ipa = (slot->base_gfn + gfn_offset + __ffs(mask)) << PAGE_SHIFT;
+ pgd = pgdp + pgd_index(ipa);
+ if (!pgd_present(*pgd))
+ goto update_mask;
+ pud = pud_offset(pgd, ipa);
+ if (!pud_present(*pud))
+ goto update_mask;
+ pmd = pmd_offset(pud, ipa);
+ if (!pmd_present(*pmd))
+ goto update_mask;
+ pte = pte_offset_kernel(pmd, ipa);
+ if (!pte_present(*pte))
+ goto update_mask;
+ if ((*pte & L_PTE_S2_RDWR) == L_PTE_S2_RDONLY)
+ goto update_mask;
+ new_pte = pfn_pte(pte_pfn(*pte), PAGE_S2);
+ *pte = new_pte;
+update_mask:
+ mask &= mask - 1;
+ }
+}
+
static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
struct kvm_memory_slot *memslot,
unsigned long fault_status)
--
1.7.9.5
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