linux-kernel - [PATCH v2 02/11] swiotlb-xen: remove start_dma

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Date:   Wed,  3 Jun 2020 15:22:38 -0700
From:   Stefano Stabellini <sstabellini@...nel.org>
To:     jgross@...e.com, boris.ostrovsky@...cle.com, konrad.wilk@...cle.com
Cc:     sstabellini@...nel.org, xen-devel@...ts.xenproject.org,
        linux-kernel@...r.kernel.org, tamas@...engyel.com,
        roman@...eda.com,
        Stefano Stabellini <stefano.stabellini@...inx.com>
Subject: [PATCH v2 02/11] swiotlb-xen: remove start_dma_addr

From: Stefano Stabellini <stefano.stabellini@...inx.com>

It is not strictly needed. Call virt_to_phys on xen_io_tlb_start
instead. It will be useful not to have a start_dma_addr around with the
next patches.

Note that virt_to_phys is not the same as xen_virt_to_bus but actually
it is used to compared again __pa(xen_io_tlb_start) as passed to
swiotlb_init_with_tbl, so virt_to_phys is actually what we want.

Signed-off-by: Stefano Stabellini <stefano.stabellini@...inx.com>
Tested-by: Corey Minyard <cminyard@...sta.com>
Tested-by: Roman Shaposhnik <roman@...eda.com>
---
Changes in v2:
- update commit message

---
---
 drivers/xen/swiotlb-xen.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
index a42129cba36e..ed09f8ac34c5 100644
--- a/drivers/xen/swiotlb-xen.c
+++ b/drivers/xen/swiotlb-xen.c
@@ -52,8 +52,6 @@ static unsigned long xen_io_tlb_nslabs;
  * Quick lookup value of the bus address of the IOTLB.
  */
 
-static u64 start_dma_addr;
-
 /*
  * Both of these functions should avoid XEN_PFN_PHYS because phys_addr_t
  * can be 32bit when dma_addr_t is 64bit leading to a loss in
@@ -241,7 +239,6 @@ int __ref xen_swiotlb_init(int verbose, bool early)
 		m_ret = XEN_SWIOTLB_EFIXUP;
 		goto error;
 	}
-	start_dma_addr = xen_virt_to_bus(xen_io_tlb_start);
 	if (early) {
 		if (swiotlb_init_with_tbl(xen_io_tlb_start, xen_io_tlb_nslabs,
 			 verbose))
@@ -389,8 +386,8 @@ static dma_addr_t xen_swiotlb_map_page(struct device *dev, struct page *page,
 	 */
 	trace_swiotlb_bounced(dev, dev_addr, size, swiotlb_force);
 
-	map = swiotlb_tbl_map_single(dev, start_dma_addr, phys,
-				     size, size, dir, attrs);
+	map = swiotlb_tbl_map_single(dev, virt_to_phys(xen_io_tlb_start),
+				     phys, size, size, dir, attrs);
 	if (map == (phys_addr_t)DMA_MAPPING_ERROR)
 		return DMA_MAPPING_ERROR;
 
-- 
2.17.1