Gregory Haskins wrote: > Hi All, > I am working on some PV stuff and had some questions about the ability > to share memory across the Guest/Host boundary. > > It seems that most examples of how to do this always involve starting > with a *page, converting it to a gfn via page_to_gfn(), and using that > as a gpa to pass across the boundary. >
Do you mean page_to_pfn? I assume you're talking about a page within the guest right? > I understand that this method avoids a software traipse through the > page-walker, so it's nice. What I can't quite figure out is what are > the other types of memory (if any) that can be passed across. > > For instance, is a pointer from kmalloc() considered a gpa, a gva, > neither? gpa = guest physical address. It's a pa or a pfn << PAGE_SHIFT. gva = guest virtual address. It's returned from pretty much anything that allocates memory (kmalloc for instance). This is all within the guest of course. > Or are gva's only pointers that come from guest-userspace, > etc. Is it possible to pass something like a skb->data pointer (I > understand that I may have to run the page-walker for some of these)? > Yes, you can pass through any gva. There are couple of things to be aware of though. When passing a gva, you have to be sure that the gva is actually mapped in memory as KVM cannot cause Linux to fault in a page. Also, for something like skb->data, you should probably just pass the gpa since they'll usually fall within a single page anyway. > If so, how would I do this: E.g. can I just pass the pointer, and then > do gva_to_hpa() on the host? Or do I need to prep the pointer before > sending it? > There's no need to prep provided that you know the va is mapped into memory in the guest. Regards, Anthony Liguori > TIA > -Greg > > > ------------------------------------------------------------------------- > This SF.net email is sponsored by: Splunk Inc. > Still grepping through log files to find problems? Stop. > Now Search log events and configuration files using AJAX and a browser. > Download your FREE copy of Splunk now >> http://get.splunk.com/ > _______________________________________________ > kvm-devel mailing list > kvm-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/kvm-devel > > ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ _______________________________________________ kvm-devel mailing list kvm-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/kvm-devel
