| Message ID | 1422605552-24797-2-git-send-email-nab@daterainc.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 30/01/2015 09:12, Nicholas A. Bellinger wrote: > From: Nicholas Bellinger <nab@linux-iscsi.org> > > This patch adds a new memcpy_fromiovec_out() library function which modifies > the passed *iov following memcpy_fromiovec(), but also returns the next current > iovec pointer via **iov_out. > > This is useful for vhost ANY_LAYOUT support when guests are allowed to generate > incoming virtio request headers combined with subsequent SGL payloads into a > single iovec. > > Cc: Michael S. Tsirkin <mst@redhat.com> > Cc: Paolo Bonzini <pbonzini@redhat.com> > Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org> > --- > include/linux/uio.h | 2 ++ > lib/iovec.c | 27 +++++++++++++++++++++++++++ > 2 files changed, 29 insertions(+) > > diff --git a/include/linux/uio.h b/include/linux/uio.h > index 1c5e453..3e4473d 100644 > --- a/include/linux/uio.h > +++ b/include/linux/uio.h > @@ -136,6 +136,8 @@ size_t csum_and_copy_to_iter(void *addr, size_t bytes, __wsum *csum, struct iov_ > size_t csum_and_copy_from_iter(void *addr, size_t bytes, __wsum *csum, struct iov_iter *i); > > int memcpy_fromiovec(unsigned char *kdata, struct iovec *iov, int len); > +int memcpy_fromiovec_out(unsigned char *kdata, struct iovec *iov, > + struct iovec **iov_out, int len); > int memcpy_fromiovecend(unsigned char *kdata, const struct iovec *iov, > int offset, int len); > int memcpy_toiovecend(const struct iovec *v, unsigned char *kdata, > diff --git a/lib/iovec.c b/lib/iovec.c > index 2d99cb4..6a813dd 100644 > --- a/lib/iovec.c > +++ b/lib/iovec.c > @@ -28,6 +28,33 @@ int memcpy_fromiovec(unsigned char *kdata, struct iovec *iov, int len) > EXPORT_SYMBOL(memcpy_fromiovec); > > /* > + * Copy iovec to kernel, saving the current iov to *iov_out. > + * Returns -EFAULT on error. Perhaps document that iov is modified, zeroing everything in [iov, *iov_out) and possibly removing the front of *iov_out? Paolo > + */ > + > +int memcpy_fromiovec_out(unsigned char *kdata, struct iovec *iov, > + struct iovec **iov_out, int len) > +{ > + while (len > 0) { > + if (iov->iov_len) { > + int copy = min_t(unsigned int, len, iov->iov_len); > + if (copy_from_user(kdata, iov->iov_base, copy)) > + return -EFAULT; > + len -= copy; > + kdata += copy; > + iov->iov_base += copy; > + iov->iov_len -= copy; > + } > + if (!iov->iov_len) > + iov++; > + } > + *iov_out = iov; > + > + return 0; > +} > +EXPORT_SYMBOL(memcpy_fromiovec_out); > + > +/* > * Copy kernel to iovec. Returns -EFAULT on error. > */ > > -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Fri, 2015-01-30 at 10:33 +0100, Paolo Bonzini wrote: > > On 30/01/2015 09:12, Nicholas A. Bellinger wrote: > > From: Nicholas Bellinger <nab@linux-iscsi.org> > > > > This patch adds a new memcpy_fromiovec_out() library function which modifies > > the passed *iov following memcpy_fromiovec(), but also returns the next current > > iovec pointer via **iov_out. > > > > This is useful for vhost ANY_LAYOUT support when guests are allowed to generate > > incoming virtio request headers combined with subsequent SGL payloads into a > > single iovec. > > > > Cc: Michael S. Tsirkin <mst@redhat.com> > > Cc: Paolo Bonzini <pbonzini@redhat.com> > > Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org> > > --- > > include/linux/uio.h | 2 ++ > > lib/iovec.c | 27 +++++++++++++++++++++++++++ > > 2 files changed, 29 insertions(+) > > <SNIP> > > --- a/lib/iovec.c > > +++ b/lib/iovec.c > > @@ -28,6 +28,33 @@ int memcpy_fromiovec(unsigned char *kdata, struct iovec *iov, int len) > > EXPORT_SYMBOL(memcpy_fromiovec); > > > > /* > > + * Copy iovec to kernel, saving the current iov to *iov_out. > > + * Returns -EFAULT on error. > > Perhaps document that iov is modified, zeroing everything in [iov, > *iov_out) and possibly removing the front of *iov_out? > Sure, updated the read the following: * Copy iovec to kernel, modifying the passed *iov entries. * * Save **iov_out for the caller to use upon return, that may either * contain the current entry with a re-calculated iov_base + iov_len * or next unmodified entry. * * Also note that any iovec entries preceding the final *iov_out are * zeroed by copy_from_user(). Thank you, --nab -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/include/linux/uio.h b/include/linux/uio.h index 1c5e453..3e4473d 100644 --- a/include/linux/uio.h +++ b/include/linux/uio.h @@ -136,6 +136,8 @@ size_t csum_and_copy_to_iter(void *addr, size_t bytes, __wsum *csum, struct iov_ size_t csum_and_copy_from_iter(void *addr, size_t bytes, __wsum *csum, struct iov_iter *i); int memcpy_fromiovec(unsigned char *kdata, struct iovec *iov, int len); +int memcpy_fromiovec_out(unsigned char *kdata, struct iovec *iov, + struct iovec **iov_out, int len); int memcpy_fromiovecend(unsigned char *kdata, const struct iovec *iov, int offset, int len); int memcpy_toiovecend(const struct iovec *v, unsigned char *kdata, diff --git a/lib/iovec.c b/lib/iovec.c index 2d99cb4..6a813dd 100644 --- a/lib/iovec.c +++ b/lib/iovec.c @@ -28,6 +28,33 @@ int memcpy_fromiovec(unsigned char *kdata, struct iovec *iov, int len) EXPORT_SYMBOL(memcpy_fromiovec); /* + * Copy iovec to kernel, saving the current iov to *iov_out. + * Returns -EFAULT on error. + */ + +int memcpy_fromiovec_out(unsigned char *kdata, struct iovec *iov, + struct iovec **iov_out, int len) +{ + while (len > 0) { + if (iov->iov_len) { + int copy = min_t(unsigned int, len, iov->iov_len); + if (copy_from_user(kdata, iov->iov_base, copy)) + return -EFAULT; + len -= copy; + kdata += copy; + iov->iov_base += copy; + iov->iov_len -= copy; + } + if (!iov->iov_len) + iov++; + } + *iov_out = iov; + + return 0; +} +EXPORT_SYMBOL(memcpy_fromiovec_out); + +/* * Copy kernel to iovec. Returns -EFAULT on error. */