[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH] xen/arm: create_p2m_entries has to flush TLBs on every CPU
Hi Ian, On 04/23/2014 12:06 PM, Ian Campbell wrote: > On Fri, 2014-04-18 at 17:12 +0100, Julien Grall wrote: >> The function create_p2m_entries creates mappings in second-level page tables >> which is shared between every CPU. > > You say create_p2m_entries twice but then patch create_xen_entries. Is > it the patch or the description which is wrong? The description is wrong, sorry. I will send a new version of this patch. > >> Only flushing TLBs on local processor may result to wrong behaviour >> when io{re,un}map is used. > > From this sounds like it's the desription? > >> Signed-off-by: Julien Grall <julien.grall@xxxxxxxxxx> >> --- >> >> This patch is candidate to be backported to Xen 4.4. >> >> create_p2m_entries is only used by vmap ( iore{,un}map functions. >> >> Upstream Xen 4.4 calls these functions only when 1 CPU is online so it's >> "safe". People might want to use them when multiple CPUs are online. >> >> Ian: Do you plan to backport your tlb series? If not, this patch will have >> to slighty change because Xen 4.4 doesn't have TLBs helper to flush xen >> data on every cpus. > > I wasn't planning to backport the tlb series, but I could look at > backporting the required bits I suppose. > > However, is it needed? Does 4.4 make any ioremap calls where this would > actually hurt? I think all the uses in xen/arch/arm/platforms/*.c are > short lived and only accessed from the current cpu. The one in > xen/drivers/video/arm_hdlcd.c is done before we go SMP anyway. There is some in serials drivers. I was thinking about people making product based Xen 4.4. They might use io{re,un}map in their own code with all CPUs up. Regards, -- Julien Grall _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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