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Subject[RFC PATCH 3/7] KVM: arm64: Traverse page table entries when sync dirty log
Date
For hardware management of dirty state, dirty state is stored in
page table entries. We have to traverse page table entries when
sync dirty log.

Signed-off-by: Keqian Zhu <zhukeqian1@huawei.com>
Signed-off-by: Peng Liang <liangpeng10@huawei.com>
---
arch/arm64/include/asm/kvm_host.h | 1 +
virt/kvm/arm/arm.c | 6 +-
virt/kvm/arm/mmu.c | 127 ++++++++++++++++++++++++++++++
3 files changed, 133 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 32c8a675e5a4..916617d3fed6 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -480,6 +480,7 @@ u64 __kvm_call_hyp(void *hypfn, ...);

void force_vm_exit(const cpumask_t *mask);
void kvm_mmu_wp_memory_region(struct kvm *kvm, int slot);
+int kvm_mmu_sync_dirty_log(struct kvm *kvm, struct kvm_memory_slot *memslot);

int handle_exit(struct kvm_vcpu *vcpu, struct kvm_run *run,
int exception_index);
diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c
index 48d0ec44ad77..975311fa3a27 100644
--- a/virt/kvm/arm/arm.c
+++ b/virt/kvm/arm/arm.c
@@ -1191,7 +1191,11 @@ long kvm_arch_vcpu_ioctl(struct file *filp,

void kvm_arch_sync_dirty_log(struct kvm *kvm, struct kvm_memory_slot *memslot)
{
-
+#ifdef CONFIG_ARM64_HW_AFDBM
+ if (kvm_hw_dbm_enabled()) {
+ kvm_mmu_sync_dirty_log(kvm, memslot);
+ }
+#endif
}

void kvm_arch_flush_remote_tlbs_memslot(struct kvm *kvm,
diff --git a/virt/kvm/arm/mmu.c b/virt/kvm/arm/mmu.c
index dc97988eb2e0..ff8df9702e04 100644
--- a/virt/kvm/arm/mmu.c
+++ b/virt/kvm/arm/mmu.c
@@ -2266,6 +2266,133 @@ int kvm_mmu_init(void)
return err;
}

+#ifdef CONFIG_ARM64_HW_AFDBM
+/**
+ * stage2_sync_dirty_log_ptes() - synchronize dirty log from PMD range
+ * @kvm: The KVM pointer
+ * @pmd: pointer to pmd entry
+ * @addr: range start address
+ * @end: range end address
+ */
+static void stage2_sync_dirty_log_ptes(struct kvm *kvm, pmd_t *pmd,
+ phys_addr_t addr, phys_addr_t end)
+{
+ pte_t *pte;
+
+ pte = pte_offset_kernel(pmd, addr);
+ do {
+ if (!pte_none(*pte) && !kvm_s2pte_readonly(pte)) {
+ mark_page_dirty(kvm, addr >> PAGE_SHIFT);
+ }
+ } while (pte++, addr += PAGE_SIZE, addr != end);
+}
+
+/**
+ * stage2_sync_dirty_log_pmds() - synchronize dirty log from PUD range
+ * @kvm: The KVM pointer
+ * @pud: pointer to pud entry
+ * @addr: range start address
+ * @end: range end address
+ */
+static void stage2_sync_dirty_log_pmds(struct kvm *kvm, pud_t *pud,
+ phys_addr_t addr, phys_addr_t end)
+{
+ pmd_t *pmd;
+ phys_addr_t next;
+
+ pmd = stage2_pmd_offset(kvm, pud, addr);
+ do {
+ next = stage2_pmd_addr_end(kvm, addr, end);
+ if (!pmd_none(*pmd) && !pmd_thp_or_huge(*pmd)) {
+ stage2_sync_dirty_log_ptes(kvm, pmd, addr, next);
+ }
+ } while (pmd++, addr = next, addr != end);
+}
+
+/**
+ * stage2_sync_dirty_log_puds() - synchronize dirty log from PGD range
+ * @kvm: The KVM pointer
+ * @pgd: pointer to pgd entry
+ * @addr: range start address
+ * @end: range end address
+ */
+static void stage2_sync_dirty_log_puds(struct kvm *kvm, pgd_t *pgd,
+ phys_addr_t addr, phys_addr_t end)
+{
+ pud_t *pud;
+ phys_addr_t next;
+
+ pud = stage2_pud_offset(kvm, pgd, addr);
+ do {
+ next = stage2_pud_addr_end(kvm, addr, end);
+ if (!stage2_pud_none(kvm, *pud) && !stage2_pud_huge(kvm, *pud)) {
+ stage2_sync_dirty_log_pmds(kvm, pud, addr, next);
+ }
+ } while (pud++, addr = next, addr != end);
+}
+
+/**
+ * stage2_sync_dirty_log_range() - synchronize dirty log from stage2 memory
+ * region range
+ * @kvm: The KVM pointer
+ * @addr: Start address of range
+ * @end: End address of range
+ */
+static void stage2_sync_dirty_log_range(struct kvm *kvm, phys_addr_t addr,
+ phys_addr_t end)
+{
+ pgd_t *pgd;
+ phys_addr_t next;
+
+ pgd = kvm->arch.pgd + stage2_pgd_index(kvm, addr);
+ do {
+ /*
+ * Release kvm_mmu_lock periodically if the memory region is
+ * large. Otherwise, we may see kernel panics with
+ * CONFIG_DETECT_HUNG_TASK, CONFIG_LOCKUP_DETECTOR,
+ * CONFIG_LOCKDEP. Additionally, holding the lock too long
+ * will also starve other vCPUs. We have to also make sure
+ * that the page tables are not freed while we released
+ * the lock.
+ */
+ cond_resched_lock(&kvm->mmu_lock);
+ if (!READ_ONCE(kvm->arch.pgd))
+ break;
+ next = stage2_pgd_addr_end(kvm, addr, end);
+ if (stage2_pgd_present(kvm, *pgd))
+ stage2_sync_dirty_log_puds(kvm, pgd, addr, next);
+ } while (pgd++, addr = next, addr != end);
+}
+
+/**
+ * kvm_mmu_sync_dirty_log() - synchronize dirty log from stage2 entries for
+ * memory slot
+ * @kvm: The KVM pointer
+ * @slot: The memory slot to synchronize dirty log
+ *
+ * Called to synchronize dirty log (marked by hw) after memory region
+ * KVM_GET_DIRTY_LOG operation is called. After this function returns
+ * all dirty log information (for that hw will modify page tables during
+ * this routine, it is true only when guest is stopped, but it is OK
+ * because we won't miss dirty log finally.) are collected into memslot
+ * dirty_bitmap. Afterwards dirty_bitmap can be copied to userspace.
+ *
+ * Acquires kvm_mmu_lock. Called with kvm->slots_lock mutex acquired,
+ * serializing operations for VM memory regions.
+ */
+int kvm_mmu_sync_dirty_log(struct kvm *kvm, struct kvm_memory_slot *memslot)
+{
+ phys_addr_t start = memslot->base_gfn << PAGE_SHIFT;
+ phys_addr_t end = (memslot->base_gfn + memslot->npages) << PAGE_SHIFT;
+
+ spin_lock(&kvm->mmu_lock);
+ stage2_sync_dirty_log_range(kvm, start, end);
+ spin_unlock(&kvm->mmu_lock);
+
+ return 0;
+}
+#endif /* CONFIG_ARM64_HW_AFDBM */
+
void kvm_arch_commit_memory_region(struct kvm *kvm,
const struct kvm_userspace_memory_region *mem,
struct kvm_memory_slot *old,
--
2.19.1
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