[PATCH V2 1/3] vfio, platform: add support for ACPI while detecting the reset driver

[PATCH V2 1/3] vfio, platform: add support for ACPI while detecting the reset driver

[Sinan Kaya]

The code is using the compatible DT string to associate a reset driver with
the actual device itself. The compatible string does not exist on ACPI
based systems. HID is the unique identifier for a device driver instead.
The change allows a driver to register with DT compatible string or ACPI
HID and then match the object with one of these conditions.

Rules for loading the reset driver are as follow:
- ACPI HID needs match for ACPI systems
- DT compat needs to match for OF systems

Tested-by: Eric Auger <eric.auger@linaro.org> (device tree only)
Tested-by: Shanker Donthineni <shankerd@codeaurora.org> (ACPI only)
Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
---
 .../vfio/platform/reset/vfio_platform_amdxgbe.c    |   4 +-
 .../platform/reset/vfio_platform_calxedaxgmac.c    |   4 +-
 drivers/vfio/platform/vfio_platform_common.c       | 107 +++++++++++++++++----
 drivers/vfio/platform/vfio_platform_private.h      |  43 +++++----
 4 files changed, 120 insertions(+), 38 deletions(-)

diff --git a/drivers/vfio/platform/reset/vfio_platform_amdxgbe.c b/drivers/vfio/platform/reset/vfio_platform_amdxgbe.c
index d4030d0..6d87442 100644
--- a/drivers/vfio/platform/reset/vfio_platform_amdxgbe.c
+++ b/drivers/vfio/platform/reset/vfio_platform_amdxgbe.c
@@ -119,7 +119,9 @@ int vfio_platform_amdxgbe_reset(struct vfio_platform_device *vdev)
 	return 0;
 }
 
-module_vfio_reset_handler("amd,xgbe-seattle-v1a", vfio_platform_amdxgbe_reset);
+module_vfio_reset_handler("amd,xgbe-seattle-v1a", NULL,
+			  vfio_platform_amdxgbe_reset);
+MODULE_ALIAS_VFIO_PLATFORM_RESET("amd,xgbe-seattle-v1a");
 
 MODULE_VERSION("0.1");
 MODULE_LICENSE("GPL v2");
diff --git a/drivers/vfio/platform/reset/vfio_platform_calxedaxgmac.c b/drivers/vfio/platform/reset/vfio_platform_calxedaxgmac.c
index e3d3d94..952dd55 100644
--- a/drivers/vfio/platform/reset/vfio_platform_calxedaxgmac.c
+++ b/drivers/vfio/platform/reset/vfio_platform_calxedaxgmac.c
@@ -77,7 +77,9 @@ int vfio_platform_calxedaxgmac_reset(struct vfio_platform_device *vdev)
 	return 0;
 }
 
-module_vfio_reset_handler("calxeda,hb-xgmac", vfio_platform_calxedaxgmac_reset);
+module_vfio_reset_handler("calxeda,hb-xgmac", NULL,
+			  vfio_platform_calxedaxgmac_reset);
+MODULE_ALIAS_VFIO_PLATFORM_RESET("calxeda,hb-xgmac");
 
 MODULE_VERSION(DRIVER_VERSION);
 MODULE_LICENSE("GPL v2");
diff --git a/drivers/vfio/platform/vfio_platform_common.c b/drivers/vfio/platform/vfio_platform_common.c
index 418cdd9..b3f6ba2 100644
--- a/drivers/vfio/platform/vfio_platform_common.c
+++ b/drivers/vfio/platform/vfio_platform_common.c
@@ -13,6 +13,7 @@
  */
 
 #include <linux/device.h>
+#include <linux/acpi.h>
 #include <linux/iommu.h>
 #include <linux/module.h>
 #include <linux/mutex.h>
@@ -31,14 +32,22 @@ static LIST_HEAD(reset_list);
 static DEFINE_MUTEX(driver_lock);
 
 static vfio_platform_reset_fn_t vfio_platform_lookup_reset(const char *compat,
-					struct module **module)
+				  const char *acpihid, struct module **module)
 {
 	struct vfio_platform_reset_node *iter;
 	vfio_platform_reset_fn_t reset_fn = NULL;
 
 	mutex_lock(&driver_lock);
 	list_for_each_entry(iter, &reset_list, link) {
-		if (!strcmp(iter->compat, compat) &&
+		if (acpihid && iter->acpihid &&
+		    !strcmp(iter->acpihid, acpihid) &&
+			try_module_get(iter->owner)) {
+			*module = iter->owner;
+			reset_fn = iter->reset;
+			break;
+		}
+		if (compat && iter->compat &&
+		    !strcmp(iter->compat, compat) &&
 			try_module_get(iter->owner)) {
 			*module = iter->owner;
 			reset_fn = iter->reset;
@@ -49,15 +58,30 @@ static vfio_platform_reset_fn_t vfio_platform_lookup_reset(const char *compat,
 	return reset_fn;
 }
 
-static void vfio_platform_get_reset(struct vfio_platform_device *vdev)
+static int vfio_platform_get_reset(struct vfio_platform_device *vdev)
 {
-	vdev->reset = vfio_platform_lookup_reset(vdev->compat,
-						&vdev->reset_module);
-	if (!vdev->reset) {
-		request_module("vfio-reset:%s", vdev->compat);
-		vdev->reset = vfio_platform_lookup_reset(vdev->compat,
-							 &vdev->reset_module);
-	}
+	int rc = -ENODEV;
+
+	vdev->reset = vfio_platform_lookup_reset(vdev->compat, vdev->acpihid,
+						 &vdev->reset_module);
+	if (vdev->reset)
+		return 0;
+
+	if (vdev->acpihid)
+		rc = request_module("vfio-reset:%s", vdev->acpihid);
+
+	if (rc && vdev->compat)
+		rc = request_module("vfio-reset:%s", vdev->compat);
+
+	if (rc)
+		return rc;
+
+	vdev->reset = vfio_platform_lookup_reset(vdev->compat, vdev->acpihid,
+						 &vdev->reset_module);
+	if (vdev->reset)
+		return 0;
+
+	return -ENODEV;
 }
 
 static void vfio_platform_put_reset(struct vfio_platform_device *vdev)
@@ -541,6 +565,46 @@ static const struct vfio_device_ops vfio_platform_ops = {
 	.mmap		= vfio_platform_mmap,
 };
 
+#ifdef CONFIG_ACPI
+int vfio_platform_probe_acpi(struct vfio_platform_device *vdev,
+			     struct device *dev)
+{
+	struct acpi_device *adev = ACPI_COMPANION(dev);
+
+	if (!adev)
+		return -ENODEV;
+
+	vdev->acpihid = acpi_device_hid(adev);
+	if (!vdev->acpihid) {
+		pr_err("VFIO: cannot find ACPI HID for %s\n",
+		       vdev->name);
+		return -ENODEV;
+	}
+	return 0;
+}
+#else
+int vfio_platform_probe_acpi(struct vfio_platform_device *vdev,
+			     struct device *dev)
+{
+	return -EINVAL;
+}
+#endif
+
+int vfio_platform_probe_of(struct vfio_platform_device *vdev,
+			   struct device *dev)
+{
+	int ret;
+
+	ret = device_property_read_string(dev, "compatible",
+					  &vdev->compat);
+	if (ret) {
+		pr_err("VFIO: cannot retrieve compat for %s\n",
+			vdev->name);
+		return ret;
+	}
+	return 0;
+}
+
 int vfio_platform_probe_common(struct vfio_platform_device *vdev,
 			       struct device *dev)
 {
@@ -550,14 +614,14 @@ int vfio_platform_probe_common(struct vfio_platform_device *vdev,
 	if (!vdev)
 		return -EINVAL;
 
-	ret = device_property_read_string(dev, "compatible", &vdev->compat);
-	if (ret) {
-		pr_err("VFIO: cannot retrieve compat for %s\n", vdev->name);
-		return -EINVAL;
-	}
+	ret = vfio_platform_probe_acpi(vdev, dev);
+	if (ret)
+		ret = vfio_platform_probe_of(vdev, dev);
 
-	vdev->device = dev;
+	if (ret)
+		return ret;
 
+	vdev->device = dev;
 	group = iommu_group_get(dev);
 	if (!group) {
 		pr_err("VFIO: No IOMMU group for device %s\n", vdev->name);
@@ -571,7 +635,6 @@ int vfio_platform_probe_common(struct vfio_platform_device *vdev,
 	}
 
 	vfio_platform_get_reset(vdev);
-
 	mutex_init(&vdev->igate);
 
 	return 0;
@@ -602,13 +665,21 @@ void __vfio_platform_register_reset(struct vfio_platform_reset_node *node)
 EXPORT_SYMBOL_GPL(__vfio_platform_register_reset);
 
 void vfio_platform_unregister_reset(const char *compat,
+				    const char *acpihid,
 				    vfio_platform_reset_fn_t fn)
 {
 	struct vfio_platform_reset_node *iter, *temp;
 
 	mutex_lock(&driver_lock);
 	list_for_each_entry_safe(iter, temp, &reset_list, link) {
-		if (!strcmp(iter->compat, compat) && (iter->reset == fn)) {
+		if (acpihid && iter->acpihid &&
+		    !strcmp(iter->acpihid, acpihid) && (iter->reset == fn)) {
+			list_del(&iter->link);
+			break;
+		}
+
+		if (compat && iter->compat &&
+		    !strcmp(iter->compat, compat) && (iter->reset == fn)) {
 			list_del(&iter->link);
 			break;
 		}
diff --git a/drivers/vfio/platform/vfio_platform_private.h b/drivers/vfio/platform/vfio_platform_private.h
index 42816dd..1b95adf 100644
--- a/drivers/vfio/platform/vfio_platform_private.h
+++ b/drivers/vfio/platform/vfio_platform_private.h
@@ -58,6 +58,7 @@ struct vfio_platform_device {
 	struct mutex			igate;
 	struct module			*parent_module;
 	const char			*compat;
+	const char			*acpihid;
 	struct module			*reset_module;
 	struct device			*device;
 
@@ -79,6 +80,7 @@ typedef int (*vfio_platform_reset_fn_t)(struct vfio_platform_device *vdev);
 struct vfio_platform_reset_node {
 	struct list_head link;
 	char *compat;
+	char *acpihid;
 	struct module *owner;
 	vfio_platform_reset_fn_t reset;
 };
@@ -98,27 +100,32 @@ extern int vfio_platform_set_irqs_ioctl(struct vfio_platform_device *vdev,
 
 extern void __vfio_platform_register_reset(struct vfio_platform_reset_node *n);
 extern void vfio_platform_unregister_reset(const char *compat,
+					   const char *acpihid,
 					   vfio_platform_reset_fn_t fn);
-#define vfio_platform_register_reset(__compat, __reset)		\
-static struct vfio_platform_reset_node __reset ## _node = {	\
-	.owner = THIS_MODULE,					\
-	.compat = __compat,					\
-	.reset = __reset,					\
-};								\
+
+#define vfio_platform_register_reset(__compat, __acpihid, __reset)	\
+static struct vfio_platform_reset_node __reset ## _node = {		\
+	.owner = THIS_MODULE,						\
+	.compat = __compat,						\
+	.acpihid = __acpihid,						\
+	.reset = __reset,						\
+};									\
 __vfio_platform_register_reset(&__reset ## _node)
 
-#define module_vfio_reset_handler(compat, reset)		\
-MODULE_ALIAS("vfio-reset:" compat);				\
-static int __init reset ## _module_init(void)			\
-{								\
-	vfio_platform_register_reset(compat, reset);		\
-	return 0;						\
-};								\
-static void __exit reset ## _module_exit(void)			\
-{								\
-	vfio_platform_unregister_reset(compat, reset);		\
-};								\
-module_init(reset ## _module_init);				\
+#define MODULE_ALIAS_VFIO_PLATFORM_RESET(name)				\
+	MODULE_ALIAS("vfio-reset:" name)
+
+#define module_vfio_reset_handler(compat, acpihid, reset)		\
+static int __init reset ## _module_init(void)				\
+{									\
+	vfio_platform_register_reset(compat, acpihid, reset);		\
+	return 0;							\
+};									\
+static void __exit reset ## _module_exit(void)				\
+{									\
+	vfio_platform_unregister_reset(compat, acpihid, reset);		\
+};									\
+module_init(reset ## _module_init);					\
 module_exit(reset ## _module_exit)
 
 #endif /* VFIO_PLATFORM_PRIVATE_H */
-- 
1.8.2.1

[PATCH V2 2/3] vfio, platform: make reset driver a requirement

[Sinan Kaya]

The code was allowing platform devices to be used without a supporting VFIO
reset driver. The hardware can be left in some inconsistent state after a
guest machine abort.

The reset driver will put the hardware back to safe state and disable
interrupts before returning the control back to the host machine.

Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
---
 drivers/vfio/platform/vfio_platform_common.c | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/drivers/vfio/platform/vfio_platform_common.c b/drivers/vfio/platform/vfio_platform_common.c
index b3f6ba2..5535fe1 100644
--- a/drivers/vfio/platform/vfio_platform_common.c
+++ b/drivers/vfio/platform/vfio_platform_common.c
@@ -165,12 +165,8 @@ static void vfio_platform_release(void *device_data)
 	mutex_lock(&driver_lock);
 
 	if (!(--vdev->refcnt)) {
-		if (vdev->reset) {
-			dev_info(vdev->device, "reset\n");
-			vdev->reset(vdev);
-		} else {
-			dev_warn(vdev->device, "no reset function found!\n");
-		}
+		dev_info(vdev->device, "reset\n");
+		vdev->reset(vdev);
 		vfio_platform_regions_cleanup(vdev);
 		vfio_platform_irq_cleanup(vdev);
 	}
@@ -634,7 +630,13 @@ int vfio_platform_probe_common(struct vfio_platform_device *vdev,
 		return ret;
 	}
 
-	vfio_platform_get_reset(vdev);
+	ret = vfio_platform_get_reset(vdev);
+	if (ret) {
+		pr_err("vfio: no reset function found for device %s\n",
+		       vdev->name);
+		iommu_group_put(group);
+		return ret;
+	}
 	mutex_init(&vdev->igate);
 
 	return 0;
-- 
1.8.2.1

[PATCH V2 3/3] vfio, platform: add QTI HIDMA reset driver

[Sinan Kaya]

In situations where the userspace driver is stopped abnormally and the
VFIO platform device is released, the assigned HW device currently is
left running. As a consequence the HW device might continue issuing IRQs
and performing DMA accesses.

This patch is implementing a reset driver for HIDMA platform driver.
This gets called by the VFIO platform reset interface.

Reviewed-by: Eric Auger <eric.auger@linaro.org>
Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
---
 drivers/vfio/platform/reset/Kconfig                |   9 ++
 drivers/vfio/platform/reset/Makefile               |   2 +
 .../vfio/platform/reset/vfio_platform_qcomhidma.c  | 101 +++++++++++++++++++++
 3 files changed, 112 insertions(+)
 create mode 100644 drivers/vfio/platform/reset/vfio_platform_qcomhidma.c

diff --git a/drivers/vfio/platform/reset/Kconfig b/drivers/vfio/platform/reset/Kconfig
index 70cccc5..d02b3b5 100644
--- a/drivers/vfio/platform/reset/Kconfig
+++ b/drivers/vfio/platform/reset/Kconfig
@@ -13,3 +13,12 @@ config VFIO_PLATFORM_AMDXGBE_RESET
 	  Enables the VFIO platform driver to handle reset for AMD XGBE
 
 	  If you don't know what to do here, say N.
+
+config VFIO_PLATFORM_QCOMHIDMA_RESET
+	tristate "VFIO support for Qualcomm Technologies HIDMA reset"
+	depends on VFIO_PLATFORM
+	help
+	  Enables the VFIO platform driver to handle reset for Qualcomm Technologies
+	  HIDMA Channel.
+
+	  If you don't know what to do here, say N.
diff --git a/drivers/vfio/platform/reset/Makefile b/drivers/vfio/platform/reset/Makefile
index 93f4e23..ec7748a 100644
--- a/drivers/vfio/platform/reset/Makefile
+++ b/drivers/vfio/platform/reset/Makefile
@@ -1,7 +1,9 @@
 vfio-platform-calxedaxgmac-y := vfio_platform_calxedaxgmac.o
 vfio-platform-amdxgbe-y := vfio_platform_amdxgbe.o
+vfio-platform-qcomhidma-y := vfio_platform_qcomhidma.o
 
 ccflags-y += -Idrivers/vfio/platform
 
 obj-$(CONFIG_VFIO_PLATFORM_CALXEDAXGMAC_RESET) += vfio-platform-calxedaxgmac.o
+obj-$(CONFIG_VFIO_PLATFORM_QCOMHIDMA_RESET) += vfio-platform-qcomhidma.o
 obj-$(CONFIG_VFIO_PLATFORM_AMDXGBE_RESET) += vfio-platform-amdxgbe.o
diff --git a/drivers/vfio/platform/reset/vfio_platform_qcomhidma.c b/drivers/vfio/platform/reset/vfio_platform_qcomhidma.c
new file mode 100644
index 0000000..103d481
--- /dev/null
+++ b/drivers/vfio/platform/reset/vfio_platform_qcomhidma.c
@@ -0,0 +1,101 @@
+/*
+ * Qualcomm Technologies HIDMA VFIO Reset Driver
+ *
+ * Copyright (c) 2016, The Linux Foundation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/device.h>
+#include <linux/iopoll.h>
+
+#include "vfio_platform_private.h"
+
+#define TRCA_CTRLSTS_OFFSET		0x000
+#define EVCA_CTRLSTS_OFFSET		0x000
+
+#define CH_CONTROL_MASK		GENMASK(7, 0)
+#define CH_STATE_MASK			GENMASK(7, 0)
+#define CH_STATE_BIT_POS		0x8
+
+#define HIDMA_CH_STATE(val)	\
+	((val >> CH_STATE_BIT_POS) & CH_STATE_MASK)
+
+#define EVCA_IRQ_EN_OFFSET		0x110
+
+#define CH_RESET			9
+#define CH_DISABLED			0
+
+int vfio_platform_qcomhidma_reset(struct vfio_platform_device *vdev)
+{
+	struct vfio_platform_region *trreg;
+	struct vfio_platform_region *evreg;
+	u32 val;
+	int ret;
+
+	if (vdev->num_regions != 2)
+		return -ENODEV;
+
+	trreg = &vdev->regions[0];
+	if (!trreg->ioaddr) {
+		trreg->ioaddr =
+			ioremap_nocache(trreg->addr, trreg->size);
+		if (!trreg->ioaddr)
+			return -ENOMEM;
+	}
+
+	evreg = &vdev->regions[1];
+	if (!evreg->ioaddr) {
+		evreg->ioaddr =
+			ioremap_nocache(evreg->addr, evreg->size);
+		if (!evreg->ioaddr)
+			return -ENOMEM;
+	}
+
+	/* disable IRQ */
+	writel(0, evreg->ioaddr + EVCA_IRQ_EN_OFFSET);
+
+	/* reset both transfer and event channels */
+	val = readl(trreg->ioaddr + TRCA_CTRLSTS_OFFSET);
+	val &= ~(CH_CONTROL_MASK << 16);
+	val |= CH_RESET << 16;
+	writel(val, trreg->ioaddr + TRCA_CTRLSTS_OFFSET);
+
+	ret = readl_poll_timeout(trreg->ioaddr + TRCA_CTRLSTS_OFFSET, val,
+				 HIDMA_CH_STATE(val) == CH_DISABLED, 1000,
+				 10000);
+	if (ret)
+		return ret;
+
+	val = readl(evreg->ioaddr + EVCA_CTRLSTS_OFFSET);
+	val &= ~(CH_CONTROL_MASK << 16);
+	val |= CH_RESET << 16;
+	writel(val, evreg->ioaddr + EVCA_CTRLSTS_OFFSET);
+
+	ret = readl_poll_timeout(evreg->ioaddr + EVCA_CTRLSTS_OFFSET, val,
+				 HIDMA_CH_STATE(val) == CH_DISABLED, 1000,
+				 10000);
+	if (ret)
+		return ret;
+
+	pr_info("HIDMA channel reset\n");
+	return 0;
+}
+module_vfio_reset_handler("qcom,hidma-1.0", "QCOM8061",
+			  vfio_platform_qcomhidma_reset);
+VFIO_PLATFORM_MODULE_ALIAS("qcom,hidma-1.0");
+VFIO_PLATFORM_MODULE_ALIAS("QCOM8061");
+
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("Reset support for Qualcomm Technologies HIDMA device");
-- 
1.8.2.1

Re: [PATCH V2 3/3] vfio, platform: add QTI HIDMA reset driver

[Sinan Kaya]

On 3/11/2016 11:54 AM, Sinan Kaya wrote:
> VFIO_PLATFORM_MODULE_ALIAS("qcom,hidma-1.0");
> +VFIO_PLATFORM_MODULE_ALIAS("QCOM8061");

I forgot to rename these to MODULE_ALIAS_VFIO_PLATFORM_RESET.

-- 
Sinan Kaya
Qualcomm Technologies, Inc. on behalf of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project

Re: [PATCH V2 3/3] vfio, platform: add QTI HIDMA reset driver

[kbuild test robot]

[-- Attachment #1: Type: text/plain, Size: 1688 bytes --]

Hi Sinan,

[auto build test ERROR on vfio/next]
[also build test ERROR on v4.5-rc7 next-20160311]
[if your patch is applied to the wrong git tree, please drop us a note to help improving the system]

url:    https://github.com/0day-ci/linux/commits/Sinan-Kaya/vfio-platform-add-HIDMA-and-ACPI-support/20160312-005737
base:   https://github.com/awilliam/linux-vfio.git next
config: arm-allmodconfig (attached as .config)
reproduce:
        wget https://git.kernel.org/cgit/linux/kernel/git/wfg/lkp-tests.git/plain/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        make.cross ARCH=arm 

All errors (new ones prefixed by >>):

>> drivers/vfio/platform/reset/vfio_platform_qcomhidma.c:97:28: error: expected declaration specifiers or '...' before string constant
    VFIO_PLATFORM_MODULE_ALIAS("qcom,hidma-1.0");
                               ^
   drivers/vfio/platform/reset/vfio_platform_qcomhidma.c:98:28: error: expected declaration specifiers or '...' before string constant
    VFIO_PLATFORM_MODULE_ALIAS("QCOM8061");
                               ^

vim +97 drivers/vfio/platform/reset/vfio_platform_qcomhidma.c

    91	
    92		pr_info("HIDMA channel reset\n");
    93		return 0;
    94	}
    95	module_vfio_reset_handler("qcom,hidma-1.0", "QCOM8061",
    96				  vfio_platform_qcomhidma_reset);
  > 97	VFIO_PLATFORM_MODULE_ALIAS("qcom,hidma-1.0");
    98	VFIO_PLATFORM_MODULE_ALIAS("QCOM8061");
    99	
   100	MODULE_LICENSE("GPL v2");

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

[-- Attachment #2: .config.gz --]
[-- Type: application/octet-stream, Size: 56252 bytes --]

Re: [PATCH V2 2/3] vfio, platform: make reset driver a requirement

[Sinan Kaya]

On 3/11/2016 11:54 AM, Sinan Kaya wrote:
> The code was allowing platform devices to be used without a supporting VFIO
> reset driver. The hardware can be left in some inconsistent state after a
> guest machine abort.
> 
> The reset driver will put the hardware back to safe state and disable
> interrupts before returning the control back to the host machine.
> 
> Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
> ---
>  drivers/vfio/platform/vfio_platform_common.c | 16 +++++++++-------
>  1 file changed, 9 insertions(+), 7 deletions(-)
> 
I was looking at the code. It looks like this is going to break VFIO AMBA. The
common implementation is shared with AMBA and platform devices.

I couldn't see a reset function for AMBA devices.

Is there anyway to write reset function for it? I have no experience with 
AMBA devices.

Would you include a reset needed flag and just not require it for AMBA? 
(I honestly don't like this idea)

-- 
Sinan Kaya
Qualcomm Technologies, Inc. on behalf of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project

Re: [PATCH V2 2/3] vfio, platform: make reset driver a requirement

[Eric Auger]

Hi Sinan,
On 03/13/2016 06:25 PM, Sinan Kaya wrote:
> On 3/11/2016 11:54 AM, Sinan Kaya wrote:
>> The code was allowing platform devices to be used without a supporting VFIO
>> reset driver. The hardware can be left in some inconsistent state after a
>> guest machine abort.
>>
>> The reset driver will put the hardware back to safe state and disable
>> interrupts before returning the control back to the host machine.
>>
>> Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
>> ---
>>  drivers/vfio/platform/vfio_platform_common.c | 16 +++++++++-------
>>  1 file changed, 9 insertions(+), 7 deletions(-)
>>
> I was looking at the code. It looks like this is going to break VFIO AMBA. The
> common implementation is shared with AMBA and platform devices.
> 
> I couldn't see a reset function for AMBA devices.
> 
> Is there anyway to write reset function for it? I have no experience with 
> AMBA devices.
To my knowledge only the PL330 DMA controller (drivers/dma/pl330.c) was
passthrough'ed at some point, rather for development purpose than
production purpose. This was done by Virtual Open Systems (ask Baptiste
for more details). But I don't think this is really used.
> 
> Would you include a reset needed flag and just not require it for AMBA? 
> (I honestly don't like this idea)
> 
I think the requirement also makes sense for AMBA.

Maybe an option would be to add a module parameter that would allow to
use the vfio platform/amba driver without reset module (with explicit
opt-in from the user). Maybe this can be done later on.

FYI I will not have access to my mailbox until the end of the week.

Best Regards

Eric

Re: [PATCH V2 2/3] vfio, platform: make reset driver a requirement

[Sinan Kaya]

Hi Baptiste,

>> I couldn't see a reset function for AMBA devices.
>>
>> Is there anyway to write reset function for it? I have no experience with 
>> AMBA devices.
> To my knowledge only the PL330 DMA controller (drivers/dma/pl330.c) was
> passthrough'ed at some point, rather for development purpose than
> production purpose. This was done by Virtual Open Systems (ask Baptiste
> for more details). But I don't think this is really used.

Are you OK with requiring reset driver for AMBA devices too? The PL330 
driver won't work until a reset driver is submitted for it.

>>
>> Would you include a reset needed flag and just not require it for AMBA? 
>> (I honestly don't like this idea)
>>
> I think the requirement also makes sense for AMBA.
> 
> Maybe an option would be to add a module parameter that would allow to
> use the vfio platform/amba driver without reset module (with explicit
> opt-in from the user). Maybe this can be done later on.

I can see this flag useful for testing purposes but it should not be used in 
production.

How about I add a module parameter which is not set by default? When set,
I don't perform the reset requirement check.

> 
> FYI I will not have access to my mailbox until the end of the week.

OK, no rush.

> 
> Best Regards
> 
> Eric
> 


-- 
Sinan Kaya
Qualcomm Technologies, Inc. on behalf of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project

Re: [PATCH V2 2/3] vfio, platform: make reset driver a requirement

[Eric Auger]

Hi Sinan,
On 03/16/2016 03:27 PM, Sinan Kaya wrote:
> Hi Baptiste,
> 
>>> I couldn't see a reset function for AMBA devices.
>>>
>>> Is there anyway to write reset function for it? I have no experience with 
>>> AMBA devices.
>> To my knowledge only the PL330 DMA controller (drivers/dma/pl330.c) was
>> passthrough'ed at some point, rather for development purpose than
>> production purpose. This was done by Virtual Open Systems (ask Baptiste
>> for more details). But I don't think this is really used.
> 
> Are you OK with requiring reset driver for AMBA devices too? The PL330 
> driver won't work until a reset driver is submitted for it.
> 
>>>
>>> Would you include a reset needed flag and just not require it for AMBA? 
>>> (I honestly don't like this idea)
>>>
>> I think the requirement also makes sense for AMBA.
>>
>> Maybe an option would be to add a module parameter that would allow to
>> use the vfio platform/amba driver without reset module (with explicit
>> opt-in from the user). Maybe this can be done later on.
> 
> I can see this flag useful for testing purposes but it should not be used in 
> production.
> 
> How about I add a module parameter which is not set by default? When set,
> I don't perform the reset requirement check.
Yes that's what I meant

Best Regards

Eric
> 
>>
>> FYI I will not have access to my mailbox until the end of the week.
> 
> OK, no rush.
> 
>>
>> Best Regards
>>
>> Eric
>>
> 
> 

Re: [PATCH V2 2/3] vfio, platform: make reset driver a requirement

[Sinan Kaya]

On 3/27/2016 11:21 AM, Eric Auger wrote:
>> How about I add a module parameter which is not set by default? When set,
>> > I don't perform the reset requirement check.
> Yes that's what I meant
> 
> Best Regards
> 
> Eric

Got it. I'll post something soon.

-- 
Sinan Kaya
Qualcomm Technologies, Inc. on behalf of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project