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From: Stefano Stabellini <sstabellini@kernel.org>
To: konrad.wilk@oracle.com, boris.ostrovsky@oracle.com, jgross@suse.com
Cc: xen-devel@lists.xenproject.org, Julien.Grall@arm.com,
	sstabellini@kernel.org
Subject: [PATCH v2] xen/swiotlb: don't initialize swiotlb twice on arm64
Date: Tue, 28 May 2019 15:48:22 -0700 (PDT)
Message-ID: <alpine.DEB.2.21.1905281546410.16734@sstabellini-ThinkPad-T480s> (raw)

From: Stefano Stabellini <stefanos@xilinx.com>

On arm64 swiotlb is often (not always) already initialized by mem_init.
We don't want to initialize it twice, which would trigger a second
memory allocation. Moreover, the second memory pool is typically made of
high pages and ends up replacing the original memory pool of low pages.
As a side effect of this change, it is possible to have low pages in
swiotlb-xen on arm64.

Signed-off-by: Stefano Stabellini <stefanos@xilinx.com>
---
Changes in v2:
- improve commit message
- don't add nested ifs

diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
index 877baf2..8a3cdd1 100644
--- a/drivers/xen/swiotlb-xen.c
+++ b/drivers/xen/swiotlb-xen.c
@@ -211,6 +211,15 @@ int __ref xen_swiotlb_init(int verbose, bool early)
 retry:
 	bytes = xen_set_nslabs(xen_io_tlb_nslabs);
 	order = get_order(xen_io_tlb_nslabs << IO_TLB_SHIFT);
+
+	/*
+	 * IO TLB memory already allocated. Just use it.
+	 */
+	if (io_tlb_start != 0) {
+		xen_io_tlb_start = phys_to_virt(io_tlb_start);
+		goto end;
+	}
+
 	/*
 	 * Get IO TLB memory from any location.
 	 */
@@ -240,7 +249,6 @@ int __ref xen_swiotlb_init(int verbose, bool early)
 		m_ret = XEN_SWIOTLB_ENOMEM;
 		goto error;
 	}
-	xen_io_tlb_end = xen_io_tlb_start + bytes;
 	/*
 	 * And replace that memory with pages under 4GB.
 	 */
@@ -267,6 +275,8 @@ int __ref xen_swiotlb_init(int verbose, bool early)
 	} else
 		rc = swiotlb_late_init_with_tbl(xen_io_tlb_start, xen_io_tlb_nslabs);
 
+end:
+	xen_io_tlb_end = xen_io_tlb_start + bytes;
 	if (!rc)
 		swiotlb_set_max_segment(PAGE_SIZE);
 
-- 
2.7.4


_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel

From: Stefano Stabellini <sstabellini@kernel.org>
To: konrad.wilk@oracle.com, boris.ostrovsky@oracle.com, jgross@suse.com
Cc: xen-devel@lists.xenproject.org, Julien.Grall@arm.com,
	sstabellini@kernel.org
Subject: [Xen-devel] [PATCH v2] xen/swiotlb: don't initialize swiotlb twice on arm64
Date: Tue, 28 May 2019 15:48:22 -0700 (PDT)
Message-ID: <alpine.DEB.2.21.1905281546410.16734@sstabellini-ThinkPad-T480s> (raw)
Message-ID: <20190528224822.rM7eZfwZSXO7-sGa7maCfLg7H_mMkrbh2myHfBF2QxU@z> (raw)

From: Stefano Stabellini <stefanos@xilinx.com>

On arm64 swiotlb is often (not always) already initialized by mem_init.
We don't want to initialize it twice, which would trigger a second
memory allocation. Moreover, the second memory pool is typically made of
high pages and ends up replacing the original memory pool of low pages.
As a side effect of this change, it is possible to have low pages in
swiotlb-xen on arm64.

Signed-off-by: Stefano Stabellini <stefanos@xilinx.com>
---
Changes in v2:
- improve commit message
- don't add nested ifs

diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
index 877baf2..8a3cdd1 100644
--- a/drivers/xen/swiotlb-xen.c
+++ b/drivers/xen/swiotlb-xen.c
@@ -211,6 +211,15 @@ int __ref xen_swiotlb_init(int verbose, bool early)
 retry:
 	bytes = xen_set_nslabs(xen_io_tlb_nslabs);
 	order = get_order(xen_io_tlb_nslabs << IO_TLB_SHIFT);
+
+	/*
+	 * IO TLB memory already allocated. Just use it.
+	 */
+	if (io_tlb_start != 0) {
+		xen_io_tlb_start = phys_to_virt(io_tlb_start);
+		goto end;
+	}
+
 	/*
 	 * Get IO TLB memory from any location.
 	 */
@@ -240,7 +249,6 @@ int __ref xen_swiotlb_init(int verbose, bool early)
 		m_ret = XEN_SWIOTLB_ENOMEM;
 		goto error;
 	}
-	xen_io_tlb_end = xen_io_tlb_start + bytes;
 	/*
 	 * And replace that memory with pages under 4GB.
 	 */
@@ -267,6 +275,8 @@ int __ref xen_swiotlb_init(int verbose, bool early)
 	} else
 		rc = swiotlb_late_init_with_tbl(xen_io_tlb_start, xen_io_tlb_nslabs);
 
+end:
+	xen_io_tlb_end = xen_io_tlb_start + bytes;
 	if (!rc)
 		swiotlb_set_max_segment(PAGE_SIZE);
 
-- 
2.7.4


_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel

             reply index

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-28 22:48 Stefano Stabellini [this message]
2019-05-28 22:48 ` [Xen-devel] " Stefano Stabellini
2019-05-28 23:50 ` Boris Ostrovsky
2019-05-28 23:50   ` [Xen-devel] " Boris Ostrovsky
2019-06-03 18:25   ` Stefano Stabellini
2019-06-03 18:25     ` [Xen-devel] " Stefano Stabellini
2019-06-03 23:16     ` Boris Ostrovsky
2019-06-03 23:16       ` [Xen-devel] " Boris Ostrovsky
2019-06-04 16:51       ` Stefano Stabellini
2019-06-04 19:41         ` Boris Ostrovsky
2019-06-05 14:13           ` Konrad Rzeszutek Wilk
2019-06-05 14:24             ` Juergen Gross
2019-06-13 14:23               ` Konrad Rzeszutek Wilk
2019-06-13 15:04                 ` Juergen Gross
2019-06-13 21:00                   ` Konrad Rzeszutek Wilk
2019-06-17  8:21                     ` Christoph Hellwig

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