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From: Stefano Stabellini <sstabellini@kernel.org>
To: xen-devel@lists.xenproject.org
Cc: sstabellini@kernel.org, boris.ostrovsky@oracle.com,
	jgross@suse.com, hch@lst.de,
	Stefano Stabellini <stefano.stabellini@xilinx.com>
Subject: [PATCH v2 3/3] xen/swiotlb: check if the swiotlb has already been initialized
Date: Wed, 12 May 2021 13:18:23 -0700	[thread overview]
Message-ID: <20210512201823.1963-3-sstabellini@kernel.org> (raw)
In-Reply-To: <alpine.DEB.2.21.2105121313060.5018@sstabellini-ThinkPad-T480s>

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

xen_swiotlb_init calls swiotlb_late_init_with_tbl, which fails with
-ENOMEM if the swiotlb has already been initialized.

Add an explicit check io_tlb_default_mem != NULL at the beginning of
xen_swiotlb_init. If the swiotlb is already initialized print a warning
and return -EEXIST.

On x86, the error propagates.

On ARM, we don't actually need a special swiotlb buffer (yet), any
buffer would do. So ignore the error and continue.

CC: boris.ostrovsky@oracle.com
CC: jgross@suse.com
Signed-off-by: Stefano Stabellini <stefano.stabellini@xilinx.com>
Reviewed-by: Boris Ostrovsky <boris.ostrvsky@oracle.com>
---
Changes in v2:
- use pr_warn
- add reviewed-by
---
 arch/arm/xen/mm.c         | 8 +++++++-
 drivers/xen/swiotlb-xen.c | 5 +++++
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/arch/arm/xen/mm.c b/arch/arm/xen/mm.c
index 223b1151fd7d..a7e54a087b80 100644
--- a/arch/arm/xen/mm.c
+++ b/arch/arm/xen/mm.c
@@ -138,9 +138,15 @@ void xen_destroy_contiguous_region(phys_addr_t pstart, unsigned int order)
 static int __init xen_mm_init(void)
 {
 	struct gnttab_cache_flush cflush;
+	int rc;
+
 	if (!xen_swiotlb_detect())
 		return 0;
-	xen_swiotlb_init();
+
+	rc = xen_swiotlb_init();
+	/* we can work with the default swiotlb */
+	if (rc < 0 && rc != -EEXIST)
+		return rc;
 
 	cflush.op = 0;
 	cflush.a.dev_bus_addr = 0;
diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
index 4c89afc0df62..24d11861ac7d 100644
--- a/drivers/xen/swiotlb-xen.c
+++ b/drivers/xen/swiotlb-xen.c
@@ -164,6 +164,11 @@ int __ref xen_swiotlb_init(void)
 	int rc = -ENOMEM;
 	char *start;
 
+	if (io_tlb_default_mem != NULL) {
+		pr_warn("swiotlb buffer already initialized\n");
+		return -EEXIST;
+	}
+
 retry:
 	m_ret = XEN_SWIOTLB_ENOMEM;
 	order = get_order(bytes);
-- 
2.17.1



  parent reply	other threads:[~2021-05-12 20:18 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-12 20:18 [PATCH v2 0/3] swiotlb-xen init fixes Stefano Stabellini
2021-05-12 20:18 ` [PATCH v2 1/3] xen/arm: move xen_swiotlb_detect to arm/swiotlb-xen.h Stefano Stabellini
2021-05-13  6:10   ` Christoph Hellwig
2021-05-14  9:59   ` Juergen Gross
2021-05-12 20:18 ` [PATCH v2 2/3] arm64: do not set SWIOTLB_NO_FORCE when swiotlb is required Stefano Stabellini
2021-05-12 20:18   ` Stefano Stabellini
2021-05-14 10:00   ` Juergen Gross
2021-05-14 10:00     ` Juergen Gross
2021-05-14 10:29   ` Catalin Marinas
2021-05-14 10:29     ` Catalin Marinas
2021-05-12 20:18 ` Stefano Stabellini [this message]
2021-05-13  6:11   ` [PATCH v2 3/3] xen/swiotlb: check if the swiotlb has already been initialized Christoph Hellwig
2021-05-14 13:56 ` [PATCH v2 0/3] swiotlb-xen init fixes Juergen Gross

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