Re: [dpdk-dev] [PATCH 2/4] eal: do not use physical addresses in IOVA as VA mode

[Burakov, Anatoly]

On 02-Apr-18 6:35 AM, santosh wrote:

On Sunday 01 April 2018 05:56 PM, Anatoly Burakov wrote:
We already use VA addresses for IOVA purposes everywhere if we're in
RTE_IOVA_VA mode:
  1) rte_malloc_virt2phy()/rte_malloc_virt2iova() always return VA addresses
  2) Because of 1), memzone's IOVA is set to VA address on reserve
  3) Because of 2), mempool's IOVA addresses are set to VA addresses

The only place where actual physical addresses are stored is in memsegs at
init time, but we're not using them anywhere, and there is no external API
to get those addresses (aside from manually iterating through memsegs), nor
should anyone care about them in RTE_IOVA_VA mode.

So, fix EAL initialization to allocate VA-contiguous segments at the start
without regard for physical addresses (as if they weren't available), and
use VA to set final IOVA addresses for all pages.

Fixes: 62196f4e0941 ("mem: rename address mapping function to IOVA")
Cc: tho...@monjalon.net
Cc: sta...@dpdk.org

Signed-off-by: Anatoly Burakov <anatoly.bura...@intel.com>
---
  lib/librte_eal/linuxapp/eal/eal_memory.c | 6 +++++-
  1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/lib/librte_eal/linuxapp/eal/eal_memory.c 
b/lib/librte_eal/linuxapp/eal/eal_memory.c
index 38853b7..ecf375b 100644
--- a/lib/librte_eal/linuxapp/eal/eal_memory.c
+++ b/lib/librte_eal/linuxapp/eal/eal_memory.c
@@ -473,6 +473,9 @@ map_all_hugepages(struct hugepage_file *hugepg_tbl, struct 
hugepage_info *hpi,
                        hugepg_tbl[i].orig_va = virtaddr;
                }
                else {
+                       /* rewrite physical addresses in IOVA as VA mode */
+                       if (rte_eal_iova_mode() == RTE_IOVA_VA)
+                               hugepg_tbl[i].physaddr = (uintptr_t)virtaddr;
                        hugepg_tbl[i].final_va = virtaddr;
                }
  
@@ -1091,7 +1094,8 @@ rte_eal_hugepage_init(void)
                                continue;
                }
  
-		if (phys_addrs_available) {
+               if (phys_addrs_available &&
+                               rte_eal_iova_mode() != RTE_IOVA_VA) {

Also can be done like below:
if (phys_addrs_available)
        /* find physical addresses for each hugepage */
        if (find_iovaaddrs(&tmp_hp[hp_offset], hpi) < 0) {

such that;
find_iovaaddrs() --> rte_mem_virt2iova().

That way avoid iova check in above if loop.
does that make sense?
Thanks.
[...]


Hi,

That was the initial implementation, however it doesn't work because we 
do two mappings, original and final, and physical addresses are found 
during original mappings (meaning, their VA's will be all over the 
place). We are interested in final VA as IOVA (after all of the sorting 
and figuring out which segments are contiguous), hence the current 
implementation.

--
Thanks,
Anatoly