[PATCH v14 3/7] KVM: x86: switch to kvm_get_dirty_log_protect

[Mario Smarduch]

Hi Paolo,

  I changed your patch a little to use a Kconfig symbol,
hope that's fine with you.

- Mario

On 11/13/2014 05:57 PM, Mario Smarduch wrote:
> From: Paolo Bonzini <pbonzini at redhat.com>
> 
> We now have a generic function that does most of the work of
> kvm_vm_ioctl_get_dirty_log, now use it.
> 
> Signed-off-by: Mario Smarduch <m.smarduch at samsung.com>
> ---
>  arch/x86/include/asm/kvm_host.h |    3 --
>  arch/x86/kvm/Kconfig            |    1 +
>  arch/x86/kvm/mmu.c              |    4 +--
>  arch/x86/kvm/x86.c              |   64 ++++++---------------------------------
>  4 files changed, 12 insertions(+), 60 deletions(-)
> 
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index 7c492ed..934dc24 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -805,9 +805,6 @@ 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 9314678..bf6b82c 100644
> --- a/arch/x86/kvm/mmu.c
> +++ b/arch/x86/kvm/mmu.c
> @@ -1224,7 +1224,7 @@ 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
> @@ -1233,7 +1233,7 @@ 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 8f1e22d..9f8ae9a 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -3606,77 +3606,31 @@ static int kvm_vm_ioctl_reinject(struct kvm *kvm,
>   *
>   *   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.
> + *   3. Copy the snapshot to the userspace.
> + *   4. Flush TLB's if needed.
>   *
> - * 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.
> + * Between 2 and 4, the guest may write to the page using the remaining TLB
> + * entry.  This is not a problem because the page is reported dirty using
> + * the snapshot taken before and step 4 ensures that writes done after
> + * exiting to userspace will be logged for the next call.
>   */
>  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;
>  }
>