From: Paolo Bonzini <pbonzini@xxxxxxxxxx>
We now have a generic function that does most of the work of
kvm_vm_ioctl_get_dirty_log, now use it.
Acked-by: Christoffer Dall <christoffer.dall@xxxxxxxxxx>
Signed-off-by: Mario Smarduch <m.smarduch@xxxxxxxxxxx>
---
arch/x86/include/asm/kvm_host.h | 3 --
arch/x86/kvm/Kconfig | 1 +
arch/x86/kvm/mmu.c | 4 +--
arch/x86/kvm/x86.c | 72 ++++++++---------------------------------
4 files changed, 16 insertions(+), 64 deletions(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 6ed0c30..ae7db3e 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -804,9 +804,6 @@ void kvm_mmu_set_mask_ptes(u64 user_mask, u64 accessed_mask,
void kvm_mmu_reset_context(struct kvm_vcpu *vcpu);
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);
void kvm_mmu_zap_all(struct kvm *kvm);
void kvm_mmu_invalidate_mmio_sptes(struct kvm *kvm);
unsigned int kvm_mmu_calculate_mmu_pages(struct kvm *kvm);
diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig
index f9d16ff..d073594 100644
--- a/arch/x86/kvm/Kconfig
+++ b/arch/x86/kvm/Kconfig
@@ -39,6 +39,7 @@ config KVM
select PERF_EVENTS
select HAVE_KVM_MSI
select HAVE_KVM_CPU_RELAX_INTERCEPT
+ select KVM_GENERIC_DIRTYLOG_READ_PROTECT
select KVM_VFIO
---help---
Support hosting fully virtualized guest machines using hardware
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 978f402..89ab64c 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -1218,7 +1218,7 @@ static bool __rmap_write_protect(struct kvm *kvm, unsigned long *rmapp,
}
/**
- * kvm_mmu_write_protect_pt_masked - write protect selected PT level pages
+ * kvm_arch_mmu_write_protect_pt_masked - write protect selected PT level pages
* @kvm: kvm instance
* @slot: slot to protect
* @gfn_offset: start of the BITS_PER_LONG pages we care about
@@ -1227,7 +1227,7 @@ static bool __rmap_write_protect(struct kvm *kvm, unsigned long *rmapp,
* Used when we do not need to care about huge page mappings: e.g. during dirty
* logging we do not have any such mappings.
*/
-void kvm_mmu_write_protect_pt_masked(struct kvm *kvm,
+void kvm_arch_mmu_write_protect_pt_masked(struct kvm *kvm,
struct kvm_memory_slot *slot,
gfn_t gfn_offset, unsigned long mask)
{
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 0033df3..80769f4 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3657,83 +3657,37 @@ static int kvm_vm_ioctl_reinject(struct kvm *kvm,
* @kvm: kvm instance
* @log: slot id and address to which we copy the log
*
- * We need to keep it in mind that VCPU threads can write to the bitmap
- * concurrently. So, to avoid losing data, we keep the following order for
- * each bit:
+ * Steps 1-4 below provide general overview of dirty page logging. See
+ * kvm_get_dirty_log_protect() function description for additional details.
+ *
+ * We call kvm_get_dirty_log_protect() to handle steps 1-3, upon return we
+ * always flush the TLB (step 4) even if previous step failed and the dirty
+ * bitmap may be corrupt. Regardless of previous outcome the KVM logging API
+ * does not preclude user space subsequent dirty log read. Flushing TLB ensures
+ * writes will be marked dirty for next log read.
*
* 1. Take a snapshot of the bit and clear it if needed.
* 2. Write protect the corresponding page.
- * 3. Flush TLB's if needed.
- * 4. Copy the snapshot to the userspace.
- *
- * Between 2 and 3, the guest may write to the page using the remaining TLB
- * entry. This is not a problem because the page will be reported dirty at
- * step 4 using the snapshot taken before and step 3 ensures that successive
- * writes will be logged for the next call.
+ * 3. Copy the snapshot to the userspace.
+ * 4. Flush TLB's if needed.
*/
int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, struct kvm_dirty_log *log)
{
- int r;
- struct kvm_memory_slot *memslot;
- unsigned long n, i;
- unsigned long *dirty_bitmap;
- unsigned long *dirty_bitmap_buffer;
bool is_dirty = false;
+ int r;
mutex_lock(&kvm->slots_lock);
- r = -EINVAL;
- 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;
- gfn_t offset;
-
- if (!dirty_bitmap[i])
- continue;
-
- is_dirty = true;
-
- mask = xchg(&dirty_bitmap[i], 0);
- dirty_bitmap_buffer[i] = mask;
-
- offset = i * BITS_PER_LONG;
- kvm_mmu_write_protect_pt_masked(kvm, memslot, offset, mask);
- }
-
- spin_unlock(&kvm->mmu_lock);
-
- /* See the comments in kvm_mmu_slot_remove_write_access(). */
- lockdep_assert_held(&kvm->slots_lock);
+ r = kvm_get_dirty_log_protect(kvm, log, &is_dirty);
/*
* All the TLBs can be flushed out of mmu lock, see the comments in
* kvm_mmu_slot_remove_write_access().
*/
+ lockdep_assert_held(&kvm->slots_lock);
if (is_dirty)
kvm_flush_remote_tlbs(kvm);
- 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;
}
--
1.9.1
--
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