Re: [Qemu-devel] [PATCH v5 2/3] block/qcow2: refactor threaded encryption code

[Maxim Levitsky <mlevitsk@redhat.com>]

On Fri, 2019-09-13 at 16:11 +0000, Vladimir Sementsov-Ogievskiy wrote:
> 13.09.2019 18:28, Maxim Levitsky wrote:
> > Change do_perform_cow_encrypt and its callee qcow2_co_encrypt
> > to just receive full host and guest offsets and in pariticular
> > remove the offset_in_cluster parameter of do_perform_cow_encrypt,
> > since it is misleading, because that offset can be larger than
> > cluster size currently.
> > 
> > Also document the qcow2_co_encrypt arguments to prevent
> > that bug from happening again
> > 
> > Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
> > ---
> >   block/qcow2-cluster.c | 30 ++++++++++++---------
> >   block/qcow2-threads.c | 62 ++++++++++++++++++++++++++++++++++---------
> >   block/qcow2.c         |  5 ++--
> >   block/qcow2.h         |  8 +++---
> >   4 files changed, 73 insertions(+), 32 deletions(-)
> > 
> > diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
> > index bfeb0241d7..e87a4637fd 100644
> > --- a/block/qcow2-cluster.c
> > +++ b/block/qcow2-cluster.c
> > @@ -463,21 +463,21 @@ static int coroutine_fn do_perform_cow_read(BlockDriverState *bs,
> >   }
> >   
> >   static bool coroutine_fn do_perform_cow_encrypt(BlockDriverState *bs,
> > -                                                uint64_t src_cluster_offset,
> > -                                                uint64_t cluster_offset,
> > -                                                unsigned offset_in_cluster,
> > +                                                uint64_t guest_offset,
> > +                                                uint64_t host_offset,
> >                                                   uint8_t *buffer,
> >                                                   unsigned bytes)
> >   {
> >       if (bytes && bs->encrypted) {
> >           BDRVQcow2State *s = bs->opaque;
> > -        assert((offset_in_cluster & ~BDRV_SECTOR_MASK) == 0);
> > -        assert((bytes & ~BDRV_SECTOR_MASK) == 0);
> > +
> > +        assert(QEMU_IS_ALIGNED(guest_offset, BDRV_SECTOR_SIZE));
> > +        assert(QEMU_IS_ALIGNED(host_offset, BDRV_SECTOR_SIZE));
> > +        assert(QEMU_IS_ALIGNED(bytes, BDRV_SECTOR_SIZE));
> >           assert(s->crypto);
> > -        if (qcow2_co_encrypt(bs,
> > -                start_of_cluster(s, cluster_offset + offset_in_cluster),
> > -                src_cluster_offset + offset_in_cluster,
> > -                buffer, bytes) < 0) {
> > +
> > +        if (qcow2_co_encrypt(bs, host_offset, guest_offset,
> > +            buffer, bytes) < 0) {
> 
> strange alignment of second line of the condition.. [1]
To be honest I am too tired currently, I think I should align to the (
of function argument if possible.
I removed the do_perform_cow_encrypt as you suggested so no issue.

> 
> >               return false;
> >           }
> >       }
> > @@ -891,11 +891,15 @@ static int perform_cow(BlockDriverState *bs, QCowL2Meta *m)
> >   
> >       /* Encrypt the data if necessary before writing it */
> >       if (bs->encrypted) {
> > -        if (!do_perform_cow_encrypt(bs, m->offset, m->alloc_offset,
> > -                                    start->offset, start_buffer,
> > +        if (!do_perform_cow_encrypt(bs,
> > +                                    m->offset + start->offset,
> > +                                    m->alloc_offset + start->offset,
> > +                                    start_buffer,
> >                                       start->nb_bytes) ||
> > -            !do_perform_cow_encrypt(bs, m->offset, m->alloc_offset,
> > -                                    end->offset, end_buffer, end->nb_bytes)) {
> > +            !do_perform_cow_encrypt(bs,
> > +                                    m->offset + end->offset,
> > +                                    m->alloc_offset + end->offset,
> > +                                    end_buffer, end->nb_bytes)) {
> 
> Looking at this now, I think that do_perform_cow_encrypt can be dropped at all,
> as it's now just an extra wrapper, sending same parameters to qcow2_co_encrypt.
> 
> I'll send a follow-up, if this patch goes as is.
I kind of agree but I didn't want to make too many changes. I do think 
now also that it is worth it.


> 
> >               ret = -EIO;
> >               goto fail;
> >           }
> > diff --git a/block/qcow2-threads.c b/block/qcow2-threads.c
> > index 3b1e63fe41..9646243a9b 100644
> > --- a/block/qcow2-threads.c
> > +++ b/block/qcow2-threads.c
> > @@ -234,15 +234,15 @@ static int qcow2_encdec_pool_func(void *opaque)
> >   }
> >   
> >   static int coroutine_fn
> > -qcow2_co_encdec(BlockDriverState *bs, uint64_t file_cluster_offset,
> > -                  uint64_t offset, void *buf, size_t len, Qcow2EncDecFunc func)
> > +qcow2_co_encdec(BlockDriverState *bs, uint64_t host_offset,
> > +                uint64_t guest_offset, void *buf, size_t len,
> > +                Qcow2EncDecFunc func)
> >   {
> >       BDRVQcow2State *s = bs->opaque;
> > +
> >       Qcow2EncDecData arg = {
> >           .block = s->crypto,
> > -        .offset = s->crypt_physical_offset ?
> > -                      file_cluster_offset + offset_into_cluster(s, offset) :
> > -                      offset,
> > +        .offset = s->crypt_physical_offset ? host_offset : guest_offset,
> >           .buf = buf,
> >           .len = len,
> >           .func = func,
> > @@ -251,18 +251,54 @@ qcow2_co_encdec(BlockDriverState *bs, uint64_t file_cluster_offset,
> >       return qcow2_co_process(bs, qcow2_encdec_pool_func, &arg);
> >   }
> >   
> > +
> > +/*
> > + * qcow2_co_encrypt()
> > + *
> > + * Encrypts one or more contiguous aligned sectors
> > + *
> > + * @host_offset - underlying storage offset of the first sector of the
> > + * data to be encrypted
> > +
> 
> asterisk missed
Too tired :-(
> 
> > + * @guest_offset - guest (virtual) offset of the first sector of the
> > + * data to be encrypted
> > + *
> > + * @buf - buffer with the data to encrypt, that after encryption
> > + *        will be written to the underlying storage device at
> > + *        @host_offset
> > + *
> > + * @len - length of the buffer (must be a BDRV_SECTOR_SIZE multiple)
> > + *
> > + * Depending on the encryption method, @host_cluster_offset and/or @guest_offset
> 
> s/host_cluster_offset/host_offset
Opps, that is leftover, I remember that I already fixed that, but I guess
I didn't.
> 
> With at least alignment[1] and s/host_cluster_offset/host_offset/ fixed:
> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
> 
> > + * may be used for generating the initialization vector for
> > + * encryption.
> > + *
> > + * Note that while the whole range must be aligned on sectors, it
> > + * does not have to be aligned on clusters and can also cross cluster
> > + * boundaries
> > + *
> 
> hmm, extra empty line IMHO.

> 
> > + */
> >   int coroutine_fn
> > -qcow2_co_encrypt(BlockDriverState *bs, uint64_t file_cluster_offset,
> > -                 uint64_t offset, void *buf, size_t len)
> > +qcow2_co_encrypt(BlockDriverState *bs, uint64_t host_offset,
> > +                 uint64_t guest_offset, void *buf, size_t len)
> >   {
> > -    return qcow2_co_encdec(bs, file_cluster_offset, offset, buf, len,
> > -                             qcrypto_block_encrypt);
> > +    return qcow2_co_encdec(bs, host_offset, guest_offset, buf, len,
> > +                           qcrypto_block_encrypt);
> >   }
> >   
> > +
> > +/*
> > + * qcow2_co_decrypt()
> > + *
> > + * Decrypts one or more contiguous aligned sectors
> > + * Similar to qcow2_co_encrypt
> > + *
> 
> and this one.
Doesn't really matter, but no problem to fix.

> 
> > + */
> > +
> >   int coroutine_fn
> > -qcow2_co_decrypt(BlockDriverState *bs, uint64_t file_cluster_offset,
> > -                 uint64_t offset, void *buf, size_t len)
> > +qcow2_co_decrypt(BlockDriverState *bs, uint64_t host_offset,
> > +                 uint64_t guest_offset, void *buf, size_t len)
> >   {
> > -    return qcow2_co_encdec(bs, file_cluster_offset, offset, buf, len,
> > -                             qcrypto_block_decrypt);
> > +    return qcow2_co_encdec(bs, host_offset, guest_offset, buf, len,
> > +                           qcrypto_block_decrypt);
> >   }
> > diff --git a/block/qcow2.c b/block/qcow2.c
> > index 57734f20cf..ac768092bb 100644
> > --- a/block/qcow2.c
> > +++ b/block/qcow2.c
> > @@ -2069,7 +2069,8 @@ static coroutine_fn int qcow2_co_preadv_part(BlockDriverState *bs,
> >   
> >                   assert((offset & (BDRV_SECTOR_SIZE - 1)) == 0);
> >                   assert((cur_bytes & (BDRV_SECTOR_SIZE - 1)) == 0);
> > -                if (qcow2_co_decrypt(bs, cluster_offset, offset,
> > +                if (qcow2_co_decrypt(bs, cluster_offset + offset_in_cluster,
> > +                                     offset,
> >                                        cluster_data, cur_bytes) < 0) {
> >                       ret = -EIO;
> >                       goto fail;
> > @@ -2288,7 +2289,7 @@ static coroutine_fn int qcow2_co_pwritev_part(
> >               qemu_iovec_to_buf(qiov, qiov_offset + bytes_done,
> >                                 cluster_data, cur_bytes);
> >   
> > -            if (qcow2_co_encrypt(bs, cluster_offset, offset,
> > +            if (qcow2_co_encrypt(bs, cluster_offset + offset_in_cluster, offset,
> >                                    cluster_data, cur_bytes) < 0) {
> >                   ret = -EIO;
> >                   goto out_unlocked;
> > diff --git a/block/qcow2.h b/block/qcow2.h
> > index 998bcdaef1..a488d761ff 100644
> > --- a/block/qcow2.h
> > +++ b/block/qcow2.h
> > @@ -758,10 +758,10 @@ ssize_t coroutine_fn
> >   qcow2_co_decompress(BlockDriverState *bs, void *dest, size_t dest_size,
> >                       const void *src, size_t src_size);
> >   int coroutine_fn
> > -qcow2_co_encrypt(BlockDriverState *bs, uint64_t file_cluster_offset,
> > -                 uint64_t offset, void *buf, size_t len);
> > +qcow2_co_encrypt(BlockDriverState *bs, uint64_t host_offset,
> > +                 uint64_t guest_offset, void *buf, size_t len);
> >   int coroutine_fn
> > -qcow2_co_decrypt(BlockDriverState *bs, uint64_t file_cluster_offset,
> > -                 uint64_t offset, void *buf, size_t len);
> > +qcow2_co_decrypt(BlockDriverState *bs, uint64_t host_offset,
> > +                 uint64_t guest_offset, void *buf, size_t len);
> >   
> >   #endif
> 


Thanks for the review,
	Best regards,
		Maxim Levitsky