| Message ID | 58356E83020000780012129C@prv-mh.provo.novell.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
> -----Original Message----- > From: Jan Beulich [mailto:JBeulich@suse.com] > Sent: 23 November 2016 09:25 > To: qemu-devel@nongnu.org > Cc: Anthony Perard <anthony.perard@citrix.com>; Paul Durrant > <Paul.Durrant@citrix.com>; Stefano Stabellini <sstabellini@kernel.org>; xen- > devel <xen-devel@lists.xenproject.org> > Subject: [PATCH 3/3] xen: ignore direction in bufioreq handling > > There's no way to communicate back read data, so only writes can ever > be usefully specified. Ignore the field, paving the road for eventually > re-using the bit for something else in a few (many?) years time. > > Signed-off-by: Jan Beulich <jbeulich@suse.com> Reviewed-by: Paul Durrant <paul.durrant@citrix.com> > > --- a/xen-hvm.c > +++ b/xen-hvm.c > @@ -997,6 +997,7 @@ static int handle_buffered_iopage(XenIOS > memset(&req, 0x00, sizeof(req)); > req.state = STATE_IOREQ_READY; > req.count = 1; > + req.dir = IOREQ_WRITE; > > for (;;) { > uint32_t rdptr = buf_page->read_pointer, wrptr; > @@ -1014,7 +1015,6 @@ static int handle_buffered_iopage(XenIOS > req.size = 1U << buf_req->size; > req.addr = buf_req->addr; > req.data = buf_req->data; > - req.dir = buf_req->dir; > req.type = buf_req->type; > xen_rmb(); > qw = (req.size == 8); > @@ -1031,10 +1031,12 @@ static int handle_buffered_iopage(XenIOS > handle_ioreq(state, &req); > > /* Only req.data may get updated by handle_ioreq(), albeit even that > - * should not happen as such data would never make it to the guest. > + * should not happen as such data would never make it to the guest (we > + * can only usefully see writes here after all). > */ > assert(req.state == STATE_IOREQ_READY); > assert(req.count == 1); > + assert(req.dir == IOREQ_WRITE); > assert(!req.data_is_ptr); > > atomic_add(&buf_page->read_pointer, qw + 1); > >
On Wed, 23 Nov 2016, Paul Durrant wrote: > > -----Original Message----- > > From: Jan Beulich [mailto:JBeulich@suse.com] > > Sent: 23 November 2016 09:25 > > To: qemu-devel@nongnu.org > > Cc: Anthony Perard <anthony.perard@citrix.com>; Paul Durrant > > <Paul.Durrant@citrix.com>; Stefano Stabellini <sstabellini@kernel.org>; xen- > > devel <xen-devel@lists.xenproject.org> > > Subject: [PATCH 3/3] xen: ignore direction in bufioreq handling > > > > There's no way to communicate back read data, so only writes can ever > > be usefully specified. Ignore the field, paving the road for eventually > > re-using the bit for something else in a few (many?) years time. > > > > Signed-off-by: Jan Beulich <jbeulich@suse.com> > > Reviewed-by: Paul Durrant <paul.durrant@citrix.com> Acked-by: Stefano Stabellini <sstabellini@kernel.org> > > > > --- a/xen-hvm.c > > +++ b/xen-hvm.c > > @@ -997,6 +997,7 @@ static int handle_buffered_iopage(XenIOS > > memset(&req, 0x00, sizeof(req)); > > req.state = STATE_IOREQ_READY; > > req.count = 1; > > + req.dir = IOREQ_WRITE; > > > > for (;;) { > > uint32_t rdptr = buf_page->read_pointer, wrptr; > > @@ -1014,7 +1015,6 @@ static int handle_buffered_iopage(XenIOS > > req.size = 1U << buf_req->size; > > req.addr = buf_req->addr; > > req.data = buf_req->data; > > - req.dir = buf_req->dir; > > req.type = buf_req->type; > > xen_rmb(); > > qw = (req.size == 8); > > @@ -1031,10 +1031,12 @@ static int handle_buffered_iopage(XenIOS > > handle_ioreq(state, &req); > > > > /* Only req.data may get updated by handle_ioreq(), albeit even that > > - * should not happen as such data would never make it to the guest. > > + * should not happen as such data would never make it to the guest (we > > + * can only usefully see writes here after all). > > */ > > assert(req.state == STATE_IOREQ_READY); > > assert(req.count == 1); > > + assert(req.dir == IOREQ_WRITE); > > assert(!req.data_is_ptr); > > > > atomic_add(&buf_page->read_pointer, qw + 1); > > > > >
--- a/xen-hvm.c +++ b/xen-hvm.c @@ -997,6 +997,7 @@ static int handle_buffered_iopage(XenIOS memset(&req, 0x00, sizeof(req)); req.state = STATE_IOREQ_READY; req.count = 1; + req.dir = IOREQ_WRITE; for (;;) { uint32_t rdptr = buf_page->read_pointer, wrptr; @@ -1014,7 +1015,6 @@ static int handle_buffered_iopage(XenIOS req.size = 1U << buf_req->size; req.addr = buf_req->addr; req.data = buf_req->data; - req.dir = buf_req->dir; req.type = buf_req->type; xen_rmb(); qw = (req.size == 8); @@ -1031,10 +1031,12 @@ static int handle_buffered_iopage(XenIOS handle_ioreq(state, &req); /* Only req.data may get updated by handle_ioreq(), albeit even that - * should not happen as such data would never make it to the guest. + * should not happen as such data would never make it to the guest (we + * can only usefully see writes here after all). */ assert(req.state == STATE_IOREQ_READY); assert(req.count == 1); + assert(req.dir == IOREQ_WRITE); assert(!req.data_is_ptr); atomic_add(&buf_page->read_pointer, qw + 1);
There's no way to communicate back read data, so only writes can ever be usefully specified. Ignore the field, paving the road for eventually re-using the bit for something else in a few (many?) years time. Signed-off-by: Jan Beulich <jbeulich@suse.com>