On Tue, 12 Apr 2016, Wei Liu wrote: > On Tue, Apr 12, 2016 at 02:38:13PM +0100, Andrew Cooper wrote: > > On 12/04/16 13:57, David Vrabel wrote: > > > On 12/04/16 11:43, Wei Liu wrote: > > >> It should be placed before first time producer and consumer are used. > > > This change isn't necessary and is confusing as this is not what this > > > barrier is for. > > > > > > The barrier needs to be between the load of prod and the load of the > > > ring contents (there's even a comment that says this). This pairs with > > > the corresponding write barrier between the store of the ring contents > > > and the store of prod (in the other end). > > > > Looking further, this code will compile to multiple reads of the page, > > because there is no ACCESS_ONCE(). This code is still vulnerable to > > XSA-155.
There is no ACCESS_ONCE in QEMU, the closest thing to it is atomic_read. > Oops, accidentally kicked over a can of worms. Should have just sent > patch 1. :-) > > Jokes aside, more time is needed to fix this properly. So maybe we > should just upstream patch #1 first. Stefano? Anthony? Sure _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel
