| Message ID | 1397837530-12301-1-git-send-email-julien.grall@linaro.org |
|---|---|
| State | Superseded, archived |
| Headers | show |
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? > 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@linaro.org> > --- > > 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. Ian.
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@linaro.org> >> --- >> >> 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,
diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c index 362bc8d..eac228c 100644 --- a/xen/arch/arm/mm.c +++ b/xen/arch/arm/mm.c @@ -845,7 +845,7 @@ static int create_xen_entries(enum xenmap_operation op, BUG(); } } - flush_xen_data_tlb_range_va_local(virt, PAGE_SIZE * nr_mfns); + flush_xen_data_tlb_range_va(virt, PAGE_SIZE * nr_mfns); rc = 0;
The function create_p2m_entries creates mappings in second-level page tables which is shared between every CPU. Only flushing TLBs on local processor may result to wrong behaviour when io{re,un}map is used. Signed-off-by: Julien Grall <julien.grall@linaro.org> --- 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. --- xen/arch/arm/mm.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)