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From: Geert Uytterhoeven <geert+renesas@glider.be>
To: Baptiste Reynal <b.reynal@virtualopensystems.com>,
	Alex Williamson <alex.williamson@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>, Alexander Graf <agraf@suse.de>,
	Magnus Damm <magnus.damm@gmail.com>,
	Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
	Wolfram Sang <wsa+renesas@sang-engineering.com>,
	kvm@vger.kernel.org, linux-renesas-soc@vger.kernel.org,
	qemu-devel@nongnu.org,
	Geert Uytterhoeven <geert+renesas@glider.be>
Subject: [PATCH/RFC 2/6] vfio: Ignore real IOMMUs if CONFIG_VFIO_NOIOMMU=y
Date: Fri,  9 Feb 2018 16:16:49 +0100	[thread overview]
Message-ID: <1518189413-2761-3-git-send-email-geert+renesas@glider.be> (raw)
In-Reply-To: <1518189413-2761-1-git-send-email-geert+renesas@glider.be>

Allow use of the No-IOMMU mode even if a real IOMMU is present.
This is useful in case the device is not part of an actual IOMMU group.

Not-Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
Question:
  - Some devices (e.g. rcar-gpio) don't use DMA, so why do they need an
    IOMMU group?
  - Even devices using DMA may do so using a separate DMAC module,
    pointed to by "dmas" DT properties (e.g. sh-sci), hence they may be
    not part of an IOMMU group.
  - How to know which devices do DMA?
---
 drivers/vfio/vfio.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
index 2bc3705a99bd2f1a..7736c3fbe468a3da 100644
--- a/drivers/vfio/vfio.c
+++ b/drivers/vfio/vfio.c
@@ -129,9 +129,13 @@ struct iommu_group *vfio_iommu_group_get(struct device *dev)
 	 * bus.  We set iommudata simply to be able to identify these groups
 	 * as special use and for reclamation later.
 	 */
-	if (group || !noiommu || iommu_present(dev->bus))
+	if (group || !noiommu)
 		return group;
 
+	if (iommu_present(dev->bus))
+		dev_warn(dev, "iommu present (%ps), ignoring\n",
+			 dev->bus->iommu_ops);
+
 	group = iommu_group_alloc();
 	if (IS_ERR(group))
 		return NULL;
-- 
2.7.4

WARNING: multiple messages have this Message-ID (diff)
From: Geert Uytterhoeven <geert+renesas@glider.be>
To: Baptiste Reynal <b.reynal@virtualopensystems.com>,
	Alex Williamson <alex.williamson@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>, Alexander Graf <agraf@suse.de>,
	Magnus Damm <magnus.damm@gmail.com>,
	Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
	Wolfram Sang <wsa+renesas@sang-engineering.com>,
	kvm@vger.kernel.org, linux-renesas-soc@vger.kernel.org,
	qemu-devel@nongnu.org,
	Geert Uytterhoeven <geert+renesas@glider.be>
Subject: [Qemu-devel] [PATCH/RFC 2/6] vfio: Ignore real IOMMUs if CONFIG_VFIO_NOIOMMU=y
Date: Fri,  9 Feb 2018 16:16:49 +0100	[thread overview]
Message-ID: <1518189413-2761-3-git-send-email-geert+renesas@glider.be> (raw)
In-Reply-To: <1518189413-2761-1-git-send-email-geert+renesas@glider.be>

Allow use of the No-IOMMU mode even if a real IOMMU is present.
This is useful in case the device is not part of an actual IOMMU group.

Not-Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
Question:
  - Some devices (e.g. rcar-gpio) don't use DMA, so why do they need an
    IOMMU group?
  - Even devices using DMA may do so using a separate DMAC module,
    pointed to by "dmas" DT properties (e.g. sh-sci), hence they may be
    not part of an IOMMU group.
  - How to know which devices do DMA?
---
 drivers/vfio/vfio.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
index 2bc3705a99bd2f1a..7736c3fbe468a3da 100644
--- a/drivers/vfio/vfio.c
+++ b/drivers/vfio/vfio.c
@@ -129,9 +129,13 @@ struct iommu_group *vfio_iommu_group_get(struct device *dev)
 	 * bus.  We set iommudata simply to be able to identify these groups
 	 * as special use and for reclamation later.
 	 */
-	if (group || !noiommu || iommu_present(dev->bus))
+	if (group || !noiommu)
 		return group;
 
+	if (iommu_present(dev->bus))
+		dev_warn(dev, "iommu present (%ps), ignoring\n",
+			 dev->bus->iommu_ops);
+
 	group = iommu_group_alloc();
 	if (IS_ERR(group))
 		return NULL;
-- 
2.7.4

  parent reply	other threads:[~2018-02-09 15:17 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-02-09 15:16 [PATCH/RFC 0/6] R-Car Gen3 GPIO Pass-Through Prototype (Linux) Geert Uytterhoeven
2018-02-09 15:16 ` [Qemu-devel] " Geert Uytterhoeven
2018-02-09 15:16 ` [PATCH/RFC 1/6] vfio: platform: Allow runtime override of reset_required Geert Uytterhoeven
2018-02-09 15:16   ` [Qemu-devel] " Geert Uytterhoeven
2018-02-09 15:16 ` Geert Uytterhoeven [this message]
2018-02-09 15:16   ` [Qemu-devel] [PATCH/RFC 2/6] vfio: Ignore real IOMMUs if CONFIG_VFIO_NOIOMMU=y Geert Uytterhoeven
2018-02-09 15:16 ` [PATCH/RFC 3/6] clk: renesas: r8a7795: Mark the GPIO6 clock critical Geert Uytterhoeven
2018-02-09 15:16   ` [Qemu-devel] " Geert Uytterhoeven
2018-02-09 15:16 ` [PATCH/RFC 4/6] arm64: renesas_defconfig: Enable VFIO_PLATFORM and VFIO_NOIOMMU Geert Uytterhoeven
2018-02-09 15:16   ` [Qemu-devel] " Geert Uytterhoeven
2018-02-09 15:16 ` [PATCH/RFC 5/6] gpio: rcar: Add virtualization workarounds Geert Uytterhoeven
2018-02-09 15:16   ` [Qemu-devel] " Geert Uytterhoeven
2018-02-09 15:16 ` [PATCH/RFC 6/6] arm64: Add virt_defconfig Geert Uytterhoeven
2018-02-09 15:16   ` [Qemu-devel] " Geert Uytterhoeven

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