xiaomi-sm8450/android_kernel_xiaomi_sm8450
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

KVM: x86: switch to kvm_get_dirty_log_protect

Browse Source 
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@linaro.org>
Signed-off-by: Mario Smarduch <m.smarduch@samsung.com>
This commit is contained in:
Paolo Bonzini
2015-01-15 15:58:54 -08:00
committed by Christoffer Dall
parent ba0513b5b8
commit e108ff2f80
4 changed files with 16 additions and 64 deletions
Download Patch File Download Diff File Expand all files Collapse all files

72
arch/x86/kvm/x86.c
View File

@@ -3748,83 +3748,37 @@ 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;
}