thr3ads.net - Linux Virtualization - [PATCH v2] virtio-mmio: Update the device to OASIS spec version [Jan 2015]

If this information is useful, please help other people find it:
Share via:

Pawel Moll

2015-Jan-20 18:12 UTC

[PATCH v2] virtio-mmio: Update the device to OASIS spec version

This patch add a support for second version of the virtio-mmio device,
which follows OASIS "Virtual I/O Device (VIRTIO) Version 1.0"
specification.

Main changes:

1. The control register symbolic names use the new device/driver
   nomenclature rather than the old guest/host one.

2. The driver detect the device version (version 1 is the pre-OASIS
   spec, version 2 is compatible with fist revision of the OASIS spec)
   and drives the device accordingly.

3. New version uses direct addressing (64 bit address split into two
   low/high register) instead of the guest page size based one,
   and addresses each part of the queue (descriptors, available, used)
   separately.

4. The device activity is now explicitly triggered by writing to the
   "queue ready" register.

5. Whole 64 bit features are properly handled now (both ways).

Signed-off-by: Pawel Moll <pawel.moll at arm.com>
---
 drivers/virtio/virtio_mmio.c | 131 ++++++++++++++++++++++++++-----------------
 include/linux/virtio_mmio.h  |  44 ++++++++++++---
 2 files changed, 118 insertions(+), 57 deletions(-)

Tested with our custom models (*not* qemu).

Changes from v1:

* added legacy/modern checks in probe and finalize_features.

Changes from RFC:

* removed the "version" sysfs attribute at its usablity  was
questioned
* added #ifndefs allowing to disable legacy register names in the header
* started using handy virtqueue_get_used/avail() functions instead of
  doing all the calculations manually
* ID 0 special handled by returning -ENODEV instead of 0 - still prints
  no error (unless you've got DEBUG for drivers/base), but doesn't
  actually bind the device

diff --git a/drivers/virtio/virtio_mmio.c b/drivers/virtio/virtio_mmio.c
index 00d115b..cad5698 100644
--- a/drivers/virtio/virtio_mmio.c
+++ b/drivers/virtio/virtio_mmio.c
@@ -1,7 +1,7 @@
 /*
  * Virtio memory mapped device driver
  *
- * Copyright 2011, ARM Ltd.
+ * Copyright 2011-2014, ARM Ltd.
  *
  * This module allows virtio devices to be used over a virtual, memory mapped
  * platform device.
@@ -50,36 +50,6 @@
  *
  *
  *
- * Registers layout (all 32-bit wide):
- *
- * offset d. name             description
- * ------ -- ---------------- -----------------
- *
- * 0x000  R  MagicValue       Magic value "virt"
- * 0x004  R  Version          Device version (current max. 1)
- * 0x008  R  DeviceID         Virtio device ID
- * 0x00c  R  VendorID         Virtio vendor ID
- *
- * 0x010  R  HostFeatures     Features supported by the host
- * 0x014  W  HostFeaturesSel  Set of host features to access via HostFeatures
- *
- * 0x020  W  GuestFeatures    Features activated by the guest
- * 0x024  W  GuestFeaturesSel Set of activated features to set via
GuestFeatures
- * 0x028  W  GuestPageSize    Size of guest's memory page in bytes
- *
- * 0x030  W  QueueSel         Queue selector
- * 0x034  R  QueueNumMax      Maximum size of the currently selected queue
- * 0x038  W  QueueNum         Queue size for the currently selected queue
- * 0x03c  W  QueueAlign       Used Ring alignment for the current queue
- * 0x040  RW QueuePFN         PFN for the currently selected queue
- *
- * 0x050  W  QueueNotify      Queue notifier
- * 0x060  R  InterruptStatus  Interrupt status register
- * 0x064  W  InterruptACK     Interrupt acknowledge register
- * 0x070  RW Status           Device status register
- *
- * 0x100+ RW                  Device-specific configuration space
- *
  * Based on Virtio PCI driver by Anthony Liguori, copyright IBM Corp. 2007
  *
  * This work is licensed under the terms of the GNU GPL, version 2 or later.
@@ -145,11 +115,16 @@ struct virtio_mmio_vq_info {
 static u64 vm_get_features(struct virtio_device *vdev)
 {
 	struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
+	u64 features;
+
+	writel(1, vm_dev->base + VIRTIO_MMIO_DEVICE_FEATURES_SEL);
+	features = readl(vm_dev->base + VIRTIO_MMIO_DEVICE_FEATURES);
+	features <<= 32;
 
-	/* TODO: Features > 32 bits */
-	writel(0, vm_dev->base + VIRTIO_MMIO_HOST_FEATURES_SEL);
+	writel(0, vm_dev->base + VIRTIO_MMIO_DEVICE_FEATURES_SEL);
+	features |= readl(vm_dev->base + VIRTIO_MMIO_DEVICE_FEATURES);
 
-	return readl(vm_dev->base + VIRTIO_MMIO_HOST_FEATURES);
+	return features;
 }
 
 static int vm_finalize_features(struct virtio_device *vdev)
@@ -159,11 +134,20 @@ static int vm_finalize_features(struct virtio_device
*vdev)
 	/* Give virtio_ring a chance to accept features. */
 	vring_transport_features(vdev);
 
-	/* Make sure we don't have any features > 32 bits! */
-	BUG_ON((u32)vdev->features != vdev->features);
+	/* Make sure there is are no mixed devices */
+	if (vm_dev->version == 2 &&
+			!__virtio_test_bit(vdev, VIRTIO_F_VERSION_1)) {
+		dev_err(&vdev->dev, "New virtio-mmio devices (version 2) must
provide VIRTIO_F_VERSION_1 feature!\n");
+		return -EINVAL;
+	}
+
+	writel(1, vm_dev->base + VIRTIO_MMIO_DRIVER_FEATURES_SEL);
+	writel((u32)(vdev->features >> 32),
+			vm_dev->base + VIRTIO_MMIO_DRIVER_FEATURES);
 
-	writel(0, vm_dev->base + VIRTIO_MMIO_GUEST_FEATURES_SEL);
-	writel(vdev->features, vm_dev->base + VIRTIO_MMIO_GUEST_FEATURES);
+	writel(0, vm_dev->base + VIRTIO_MMIO_DRIVER_FEATURES_SEL);
+	writel((u32)vdev->features,
+			vm_dev->base + VIRTIO_MMIO_DRIVER_FEATURES);
 
 	return 0;
 }
@@ -275,7 +259,12 @@ static void vm_del_vq(struct virtqueue *vq)
 
 	/* Select and deactivate the queue */
 	writel(index, vm_dev->base + VIRTIO_MMIO_QUEUE_SEL);
-	writel(0, vm_dev->base + VIRTIO_MMIO_QUEUE_PFN);
+	if (vm_dev->version == 1) {
+		writel(0, vm_dev->base + VIRTIO_MMIO_QUEUE_PFN);
+	} else {
+		writel(0, vm_dev->base + VIRTIO_MMIO_QUEUE_READY);
+		WARN_ON(readl(vm_dev->base + VIRTIO_MMIO_QUEUE_READY));
+	}
 
 	size = PAGE_ALIGN(vring_size(info->num, VIRTIO_MMIO_VRING_ALIGN));
 	free_pages_exact(info->queue, size);
@@ -312,7 +301,8 @@ static struct virtqueue *vm_setup_vq(struct virtio_device
*vdev, unsigned index,
 	writel(index, vm_dev->base + VIRTIO_MMIO_QUEUE_SEL);
 
 	/* Queue shouldn't already be set up. */
-	if (readl(vm_dev->base + VIRTIO_MMIO_QUEUE_PFN)) {
+	if (readl(vm_dev->base + (vm_dev->version == 1 ?
+			VIRTIO_MMIO_QUEUE_PFN : VIRTIO_MMIO_QUEUE_READY))) {
 		err = -ENOENT;
 		goto error_available;
 	}
@@ -356,13 +346,6 @@ static struct virtqueue *vm_setup_vq(struct virtio_device
*vdev, unsigned index,
 		info->num /= 2;
 	}
 
-	/* Activate the queue */
-	writel(info->num, vm_dev->base + VIRTIO_MMIO_QUEUE_NUM);
-	writel(VIRTIO_MMIO_VRING_ALIGN,
-			vm_dev->base + VIRTIO_MMIO_QUEUE_ALIGN);
-	writel(virt_to_phys(info->queue) >> PAGE_SHIFT,
-			vm_dev->base + VIRTIO_MMIO_QUEUE_PFN);
-
 	/* Create the vring */
 	vq = vring_new_virtqueue(index, info->num, VIRTIO_MMIO_VRING_ALIGN, vdev,
 				 true, info->queue, vm_notify, callback, name);
@@ -371,6 +354,33 @@ static struct virtqueue *vm_setup_vq(struct virtio_device
*vdev, unsigned index,
 		goto error_new_virtqueue;
 	}
 
+	/* Activate the queue */
+	writel(info->num, vm_dev->base + VIRTIO_MMIO_QUEUE_NUM);
+	if (vm_dev->version == 1) {
+		writel(PAGE_SIZE, vm_dev->base + VIRTIO_MMIO_QUEUE_ALIGN);
+		writel(virt_to_phys(info->queue) >> PAGE_SHIFT,
+				vm_dev->base + VIRTIO_MMIO_QUEUE_PFN);
+	} else {
+		u64 addr;
+
+		addr = virt_to_phys(info->queue);
+		writel((u32)addr, vm_dev->base + VIRTIO_MMIO_QUEUE_DESC_LOW);
+		writel((u32)(addr >> 32),
+				vm_dev->base + VIRTIO_MMIO_QUEUE_DESC_HIGH);
+
+		addr = virt_to_phys(virtqueue_get_avail(vq));
+		writel((u32)addr, vm_dev->base + VIRTIO_MMIO_QUEUE_AVAIL_LOW);
+		writel((u32)(addr >> 32),
+				vm_dev->base + VIRTIO_MMIO_QUEUE_AVAIL_HIGH);
+
+		addr = virt_to_phys(virtqueue_get_used(vq));
+		writel((u32)addr, vm_dev->base + VIRTIO_MMIO_QUEUE_USED_LOW);
+		writel((u32)(addr >> 32),
+				vm_dev->base + VIRTIO_MMIO_QUEUE_USED_HIGH);
+
+		writel(1, vm_dev->base + VIRTIO_MMIO_QUEUE_READY);
+	}
+
 	vq->priv = info;
 	info->vq = vq;
 
@@ -381,7 +391,12 @@ static struct virtqueue *vm_setup_vq(struct virtio_device
*vdev, unsigned index,
 	return vq;
 
 error_new_virtqueue:
-	writel(0, vm_dev->base + VIRTIO_MMIO_QUEUE_PFN);
+	if (vm_dev->version == 1) {
+		writel(0, vm_dev->base + VIRTIO_MMIO_QUEUE_PFN);
+	} else {
+		writel(0, vm_dev->base + VIRTIO_MMIO_QUEUE_READY);
+		WARN_ON(readl(vm_dev->base + VIRTIO_MMIO_QUEUE_READY));
+	}
 	free_pages_exact(info->queue, size);
 error_alloc_pages:
 	kfree(info);
@@ -476,16 +491,32 @@ static int virtio_mmio_probe(struct platform_device *pdev)
 
 	/* Check device version */
 	vm_dev->version = readl(vm_dev->base + VIRTIO_MMIO_VERSION);
-	if (vm_dev->version != 1) {
+	if (vm_dev->version < 1 || vm_dev->version > 2) {
 		dev_err(&pdev->dev, "Version %ld not supported!\n",
 				vm_dev->version);
 		return -ENXIO;
 	}
 
 	vm_dev->vdev.id.device = readl(vm_dev->base + VIRTIO_MMIO_DEVICE_ID);
+	if (vm_dev->vdev.id.device == 0) {
+		/*
+		 * virtio-mmio device with an ID 0 is a (dummy) placeholder
+		 * with no function. End probing now with no error reported.
+		 */
+		return -ENODEV;
+	}
 	vm_dev->vdev.id.vendor = readl(vm_dev->base + VIRTIO_MMIO_VENDOR_ID);
 
-	writel(PAGE_SIZE, vm_dev->base + VIRTIO_MMIO_GUEST_PAGE_SIZE);
+	/* Reject legacy-only IDs for version 2 devices */
+	if (vm_dev->version == 2 &&
+			virtio_device_is_legacy_only(vm_dev->vdev.id)) {
+		dev_err(&pdev->dev, "Version 2 not supported for devices
%u!\n",
+				vm_dev->vdev.id.device);
+		return -ENODEV;
+	}
+
+	if (vm_dev->version == 1)
+		writel(PAGE_SIZE, vm_dev->base + VIRTIO_MMIO_GUEST_PAGE_SIZE);
 
 	platform_set_drvdata(pdev, vm_dev);
 
diff --git a/include/linux/virtio_mmio.h b/include/linux/virtio_mmio.h
index 5c7b6f0..c4b0968 100644
--- a/include/linux/virtio_mmio.h
+++ b/include/linux/virtio_mmio.h
@@ -51,23 +51,29 @@
 /* Virtio vendor ID - Read Only */
 #define VIRTIO_MMIO_VENDOR_ID		0x00c
 
-/* Bitmask of the features supported by the host
+/* Bitmask of the features supported by the device (host)
  * (32 bits per set) - Read Only */
-#define VIRTIO_MMIO_HOST_FEATURES	0x010
+#define VIRTIO_MMIO_DEVICE_FEATURES	0x010
 
-/* Host features set selector - Write Only */
-#define VIRTIO_MMIO_HOST_FEATURES_SEL	0x014
+/* Device (host) features set selector - Write Only */
+#define VIRTIO_MMIO_DEVICE_FEATURES_SEL	0x014
 
-/* Bitmask of features activated by the guest
+/* Bitmask of features activated by the driver (guest)
  * (32 bits per set) - Write Only */
-#define VIRTIO_MMIO_GUEST_FEATURES	0x020
+#define VIRTIO_MMIO_DRIVER_FEATURES	0x020
 
 /* Activated features set selector - Write Only */
-#define VIRTIO_MMIO_GUEST_FEATURES_SEL	0x024
+#define VIRTIO_MMIO_DRIVER_FEATURES_SEL	0x024
+
+
+#ifndef VIRTIO_MMIO_NO_LEGACY /* LEGACY DEVICES ONLY! */
 
 /* Guest's memory page size in bytes - Write Only */
 #define VIRTIO_MMIO_GUEST_PAGE_SIZE	0x028
 
+#endif
+
+
 /* Queue selector - Write Only */
 #define VIRTIO_MMIO_QUEUE_SEL		0x030
 
@@ -77,12 +83,21 @@
 /* Queue size for the currently selected queue - Write Only */
 #define VIRTIO_MMIO_QUEUE_NUM		0x038
 
+
+#ifndef VIRTIO_MMIO_NO_LEGACY /* LEGACY DEVICES ONLY! */
+
 /* Used Ring alignment for the currently selected queue - Write Only */
 #define VIRTIO_MMIO_QUEUE_ALIGN		0x03c
 
 /* Guest's PFN for the currently selected queue - Read Write */
 #define VIRTIO_MMIO_QUEUE_PFN		0x040
 
+#endif
+
+
+/* Ready bit for the currently selected queue - Read Write */
+#define VIRTIO_MMIO_QUEUE_READY		0x044
+
 /* Queue notifier - Write Only */
 #define VIRTIO_MMIO_QUEUE_NOTIFY	0x050
 
@@ -95,6 +110,21 @@
 /* Device status register - Read Write */
 #define VIRTIO_MMIO_STATUS		0x070
 
+/* Selected queue's Descriptor Table address, 64 bits in two halves */
+#define VIRTIO_MMIO_QUEUE_DESC_LOW	0x080
+#define VIRTIO_MMIO_QUEUE_DESC_HIGH	0x084
+
+/* Selected queue's Available Ring address, 64 bits in two halves */
+#define VIRTIO_MMIO_QUEUE_AVAIL_LOW	0x090
+#define VIRTIO_MMIO_QUEUE_AVAIL_HIGH	0x094
+
+/* Selected queue's Used Ring address, 64 bits in two halves */
+#define VIRTIO_MMIO_QUEUE_USED_LOW	0x0a0
+#define VIRTIO_MMIO_QUEUE_USED_HIGH	0x0a4
+
+/* Configuration atomicity value */
+#define VIRTIO_MMIO_CONFIG_GENERATION	0x0fc
+
 /* The config space is defined by each driver as
  * the per-driver configuration space - Read Write */
 #define VIRTIO_MMIO_CONFIG		0x100
-- 
2.1.0

Michael S. Tsirkin

2015-Jan-20 18:33 UTC

head link

[PATCH v2] virtio-mmio: Update the device to OASIS spec version

On Tue, Jan 20, 2015 at 06:12:11PM +0000, Pawel Moll
wrote:> This patch add a support for second version of the virtio-mmio device,
> which follows OASIS "Virtual I/O Device (VIRTIO) Version 1.0"
> specification.
> 
> Main changes:
> 
> 1. The control register symbolic names use the new device/driver
>    nomenclature rather than the old guest/host one.
> 
> 2. The driver detect the device version (version 1 is the pre-OASIS
>    spec, version 2 is compatible with fist revision of the OASIS spec)
>    and drives the device accordingly.
> 
> 3. New version uses direct addressing (64 bit address split into two
>    low/high register) instead of the guest page size based one,
>    and addresses each part of the queue (descriptors, available, used)
>    separately.
> 
> 4. The device activity is now explicitly triggered by writing to the
>    "queue ready" register.
> 
> 5. Whole 64 bit features are properly handled now (both ways).
> 
> Signed-off-by: Pawel Moll <pawel.moll at arm.com>
Acked-by: Michael S. Tsirkin <mst at redhat.com>
> ---
>  drivers/virtio/virtio_mmio.c | 131
++++++++++++++++++++++++++-----------------
>  include/linux/virtio_mmio.h  |  44 ++++++++++++---
>  2 files changed, 118 insertions(+), 57 deletions(-)
> 
> Tested with our custom models (*not* qemu).
> 
> Changes from v1:
> 
> * added legacy/modern checks in probe and finalize_features.
> 
> Changes from RFC:
> 
> * removed the "version" sysfs attribute at its usablity  was
questioned
> * added #ifndefs allowing to disable legacy register names in the header
> * started using handy virtqueue_get_used/avail() functions instead of
>   doing all the calculations manually
> * ID 0 special handled by returning -ENODEV instead of 0 - still prints
>   no error (unless you've got DEBUG for drivers/base), but doesn't
>   actually bind the device
> 
> diff --git a/drivers/virtio/virtio_mmio.c b/drivers/virtio/virtio_mmio.c
> index 00d115b..cad5698 100644
> --- a/drivers/virtio/virtio_mmio.c
> +++ b/drivers/virtio/virtio_mmio.c
> @@ -1,7 +1,7 @@
>  /*
>   * Virtio memory mapped device driver
>   *
> - * Copyright 2011, ARM Ltd.
> + * Copyright 2011-2014, ARM Ltd.
>   *
>   * This module allows virtio devices to be used over a virtual, memory
mapped
>   * platform device.
> @@ -50,36 +50,6 @@
>   *
>   *
>   *
> - * Registers layout (all 32-bit wide):
> - *
> - * offset d. name             description
> - * ------ -- ---------------- -----------------
> - *
> - * 0x000  R  MagicValue       Magic value "virt"
> - * 0x004  R  Version          Device version (current max. 1)
> - * 0x008  R  DeviceID         Virtio device ID
> - * 0x00c  R  VendorID         Virtio vendor ID
> - *
> - * 0x010  R  HostFeatures     Features supported by the host
> - * 0x014  W  HostFeaturesSel  Set of host features to access via
HostFeatures
> - *
> - * 0x020  W  GuestFeatures    Features activated by the guest
> - * 0x024  W  GuestFeaturesSel Set of activated features to set via
GuestFeatures
> - * 0x028  W  GuestPageSize    Size of guest's memory page in bytes
> - *
> - * 0x030  W  QueueSel         Queue selector
> - * 0x034  R  QueueNumMax      Maximum size of the currently selected queue
> - * 0x038  W  QueueNum         Queue size for the currently selected queue
> - * 0x03c  W  QueueAlign       Used Ring alignment for the current queue
> - * 0x040  RW QueuePFN         PFN for the currently selected queue
> - *
> - * 0x050  W  QueueNotify      Queue notifier
> - * 0x060  R  InterruptStatus  Interrupt status register
> - * 0x064  W  InterruptACK     Interrupt acknowledge register
> - * 0x070  RW Status           Device status register
> - *
> - * 0x100+ RW                  Device-specific configuration space
> - *
>   * Based on Virtio PCI driver by Anthony Liguori, copyright IBM Corp. 2007
>   *
>   * This work is licensed under the terms of the GNU GPL, version 2 or
later.
> @@ -145,11 +115,16 @@ struct virtio_mmio_vq_info {
>  static u64 vm_get_features(struct virtio_device *vdev)
>  {
>  	struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
> +	u64 features;
> +
> +	writel(1, vm_dev->base + VIRTIO_MMIO_DEVICE_FEATURES_SEL);
> +	features = readl(vm_dev->base + VIRTIO_MMIO_DEVICE_FEATURES);
> +	features <<= 32;
>  
> -	/* TODO: Features > 32 bits */
> -	writel(0, vm_dev->base + VIRTIO_MMIO_HOST_FEATURES_SEL);
> +	writel(0, vm_dev->base + VIRTIO_MMIO_DEVICE_FEATURES_SEL);
> +	features |= readl(vm_dev->base + VIRTIO_MMIO_DEVICE_FEATURES);
>  
> -	return readl(vm_dev->base + VIRTIO_MMIO_HOST_FEATURES);
> +	return features;
>  }
>  
>  static int vm_finalize_features(struct virtio_device *vdev)
> @@ -159,11 +134,20 @@ static int vm_finalize_features(struct virtio_device
*vdev)
>  	/* Give virtio_ring a chance to accept features. */
>  	vring_transport_features(vdev);
>  
> -	/* Make sure we don't have any features > 32 bits! */
> -	BUG_ON((u32)vdev->features != vdev->features);
> +	/* Make sure there is are no mixed devices */
> +	if (vm_dev->version == 2 &&
> +			!__virtio_test_bit(vdev, VIRTIO_F_VERSION_1)) {
> +		dev_err(&vdev->dev, "New virtio-mmio devices (version 2)
must provide VIRTIO_F_VERSION_1 feature!\n");
> +		return -EINVAL;
> +	}
> +
> +	writel(1, vm_dev->base + VIRTIO_MMIO_DRIVER_FEATURES_SEL);
> +	writel((u32)(vdev->features >> 32),
> +			vm_dev->base + VIRTIO_MMIO_DRIVER_FEATURES);
>  
> -	writel(0, vm_dev->base + VIRTIO_MMIO_GUEST_FEATURES_SEL);
> -	writel(vdev->features, vm_dev->base + VIRTIO_MMIO_GUEST_FEATURES);
> +	writel(0, vm_dev->base + VIRTIO_MMIO_DRIVER_FEATURES_SEL);
> +	writel((u32)vdev->features,
> +			vm_dev->base + VIRTIO_MMIO_DRIVER_FEATURES);
>  
>  	return 0;
>  }
> @@ -275,7 +259,12 @@ static void vm_del_vq(struct virtqueue *vq)
>  
>  	/* Select and deactivate the queue */
>  	writel(index, vm_dev->base + VIRTIO_MMIO_QUEUE_SEL);
> -	writel(0, vm_dev->base + VIRTIO_MMIO_QUEUE_PFN);
> +	if (vm_dev->version == 1) {
> +		writel(0, vm_dev->base + VIRTIO_MMIO_QUEUE_PFN);
> +	} else {
> +		writel(0, vm_dev->base + VIRTIO_MMIO_QUEUE_READY);
> +		WARN_ON(readl(vm_dev->base + VIRTIO_MMIO_QUEUE_READY));
> +	}
>  
>  	size = PAGE_ALIGN(vring_size(info->num, VIRTIO_MMIO_VRING_ALIGN));
>  	free_pages_exact(info->queue, size);
> @@ -312,7 +301,8 @@ static struct virtqueue *vm_setup_vq(struct
virtio_device *vdev, unsigned index,
>  	writel(index, vm_dev->base + VIRTIO_MMIO_QUEUE_SEL);
>  
>  	/* Queue shouldn't already be set up. */
> -	if (readl(vm_dev->base + VIRTIO_MMIO_QUEUE_PFN)) {
> +	if (readl(vm_dev->base + (vm_dev->version == 1 ?
> +			VIRTIO_MMIO_QUEUE_PFN : VIRTIO_MMIO_QUEUE_READY))) {
>  		err = -ENOENT;
>  		goto error_available;
>  	}
> @@ -356,13 +346,6 @@ static struct virtqueue *vm_setup_vq(struct
virtio_device *vdev, unsigned index,
>  		info->num /= 2;
>  	}
>  
> -	/* Activate the queue */
> -	writel(info->num, vm_dev->base + VIRTIO_MMIO_QUEUE_NUM);
> -	writel(VIRTIO_MMIO_VRING_ALIGN,
> -			vm_dev->base + VIRTIO_MMIO_QUEUE_ALIGN);
> -	writel(virt_to_phys(info->queue) >> PAGE_SHIFT,
> -			vm_dev->base + VIRTIO_MMIO_QUEUE_PFN);
> -
>  	/* Create the vring */
>  	vq = vring_new_virtqueue(index, info->num, VIRTIO_MMIO_VRING_ALIGN,
vdev,
>  				 true, info->queue, vm_notify, callback, name);
> @@ -371,6 +354,33 @@ static struct virtqueue *vm_setup_vq(struct
virtio_device *vdev, unsigned index,
>  		goto error_new_virtqueue;
>  	}
>  
> +	/* Activate the queue */
> +	writel(info->num, vm_dev->base + VIRTIO_MMIO_QUEUE_NUM);
> +	if (vm_dev->version == 1) {
> +		writel(PAGE_SIZE, vm_dev->base + VIRTIO_MMIO_QUEUE_ALIGN);
> +		writel(virt_to_phys(info->queue) >> PAGE_SHIFT,
> +				vm_dev->base + VIRTIO_MMIO_QUEUE_PFN);
> +	} else {
> +		u64 addr;
> +
> +		addr = virt_to_phys(info->queue);
> +		writel((u32)addr, vm_dev->base + VIRTIO_MMIO_QUEUE_DESC_LOW);
> +		writel((u32)(addr >> 32),
> +				vm_dev->base + VIRTIO_MMIO_QUEUE_DESC_HIGH);
> +
> +		addr = virt_to_phys(virtqueue_get_avail(vq));
> +		writel((u32)addr, vm_dev->base + VIRTIO_MMIO_QUEUE_AVAIL_LOW);
> +		writel((u32)(addr >> 32),
> +				vm_dev->base + VIRTIO_MMIO_QUEUE_AVAIL_HIGH);
> +
> +		addr = virt_to_phys(virtqueue_get_used(vq));
> +		writel((u32)addr, vm_dev->base + VIRTIO_MMIO_QUEUE_USED_LOW);
> +		writel((u32)(addr >> 32),
> +				vm_dev->base + VIRTIO_MMIO_QUEUE_USED_HIGH);
> +
> +		writel(1, vm_dev->base + VIRTIO_MMIO_QUEUE_READY);
> +	}
> +
>  	vq->priv = info;
>  	info->vq = vq;
>  
> @@ -381,7 +391,12 @@ static struct virtqueue *vm_setup_vq(struct
virtio_device *vdev, unsigned index,
>  	return vq;
>  
>  error_new_virtqueue:
> -	writel(0, vm_dev->base + VIRTIO_MMIO_QUEUE_PFN);
> +	if (vm_dev->version == 1) {
> +		writel(0, vm_dev->base + VIRTIO_MMIO_QUEUE_PFN);
> +	} else {
> +		writel(0, vm_dev->base + VIRTIO_MMIO_QUEUE_READY);
> +		WARN_ON(readl(vm_dev->base + VIRTIO_MMIO_QUEUE_READY));
> +	}
>  	free_pages_exact(info->queue, size);
>  error_alloc_pages:
>  	kfree(info);
> @@ -476,16 +491,32 @@ static int virtio_mmio_probe(struct platform_device
*pdev)
>  
>  	/* Check device version */
>  	vm_dev->version = readl(vm_dev->base + VIRTIO_MMIO_VERSION);
> -	if (vm_dev->version != 1) {
> +	if (vm_dev->version < 1 || vm_dev->version > 2) {
>  		dev_err(&pdev->dev, "Version %ld not supported!\n",
>  				vm_dev->version);
>  		return -ENXIO;
>  	}
>  
>  	vm_dev->vdev.id.device = readl(vm_dev->base +
VIRTIO_MMIO_DEVICE_ID);
> +	if (vm_dev->vdev.id.device == 0) {
> +		/*
> +		 * virtio-mmio device with an ID 0 is a (dummy) placeholder
> +		 * with no function. End probing now with no error reported.
> +		 */
> +		return -ENODEV;
> +	}
>  	vm_dev->vdev.id.vendor = readl(vm_dev->base +
VIRTIO_MMIO_VENDOR_ID);
>  
> -	writel(PAGE_SIZE, vm_dev->base + VIRTIO_MMIO_GUEST_PAGE_SIZE);
> +	/* Reject legacy-only IDs for version 2 devices */
> +	if (vm_dev->version == 2 &&
> +			virtio_device_is_legacy_only(vm_dev->vdev.id)) {
> +		dev_err(&pdev->dev, "Version 2 not supported for devices
%u!\n",
> +				vm_dev->vdev.id.device);
> +		return -ENODEV;
> +	}
> +
> +	if (vm_dev->version == 1)
> +		writel(PAGE_SIZE, vm_dev->base + VIRTIO_MMIO_GUEST_PAGE_SIZE);
>  
>  	platform_set_drvdata(pdev, vm_dev);
>  
> diff --git a/include/linux/virtio_mmio.h b/include/linux/virtio_mmio.h
> index 5c7b6f0..c4b0968 100644
> --- a/include/linux/virtio_mmio.h
> +++ b/include/linux/virtio_mmio.h
> @@ -51,23 +51,29 @@
>  /* Virtio vendor ID - Read Only */
>  #define VIRTIO_MMIO_VENDOR_ID		0x00c
>  
> -/* Bitmask of the features supported by the host
> +/* Bitmask of the features supported by the device (host)
>   * (32 bits per set) - Read Only */
> -#define VIRTIO_MMIO_HOST_FEATURES	0x010
> +#define VIRTIO_MMIO_DEVICE_FEATURES	0x010
>  
> -/* Host features set selector - Write Only */
> -#define VIRTIO_MMIO_HOST_FEATURES_SEL	0x014
> +/* Device (host) features set selector - Write Only */
> +#define VIRTIO_MMIO_DEVICE_FEATURES_SEL	0x014
>  
> -/* Bitmask of features activated by the guest
> +/* Bitmask of features activated by the driver (guest)
>   * (32 bits per set) - Write Only */
> -#define VIRTIO_MMIO_GUEST_FEATURES	0x020
> +#define VIRTIO_MMIO_DRIVER_FEATURES	0x020
>  
>  /* Activated features set selector - Write Only */
> -#define VIRTIO_MMIO_GUEST_FEATURES_SEL	0x024
> +#define VIRTIO_MMIO_DRIVER_FEATURES_SEL	0x024
> +
> +
> +#ifndef VIRTIO_MMIO_NO_LEGACY /* LEGACY DEVICES ONLY! */
>  
>  /* Guest's memory page size in bytes - Write Only */
>  #define VIRTIO_MMIO_GUEST_PAGE_SIZE	0x028
>  
> +#endif
> +
> +
>  /* Queue selector - Write Only */
>  #define VIRTIO_MMIO_QUEUE_SEL		0x030
>  
> @@ -77,12 +83,21 @@
>  /* Queue size for the currently selected queue - Write Only */
>  #define VIRTIO_MMIO_QUEUE_NUM		0x038
>  
> +
> +#ifndef VIRTIO_MMIO_NO_LEGACY /* LEGACY DEVICES ONLY! */
> +
>  /* Used Ring alignment for the currently selected queue - Write Only */
>  #define VIRTIO_MMIO_QUEUE_ALIGN		0x03c
>  
>  /* Guest's PFN for the currently selected queue - Read Write */
>  #define VIRTIO_MMIO_QUEUE_PFN		0x040
>  
> +#endif
> +
> +
> +/* Ready bit for the currently selected queue - Read Write */
> +#define VIRTIO_MMIO_QUEUE_READY		0x044
> +
>  /* Queue notifier - Write Only */
>  #define VIRTIO_MMIO_QUEUE_NOTIFY	0x050
>  
> @@ -95,6 +110,21 @@
>  /* Device status register - Read Write */
>  #define VIRTIO_MMIO_STATUS		0x070
>  
> +/* Selected queue's Descriptor Table address, 64 bits in two halves */
> +#define VIRTIO_MMIO_QUEUE_DESC_LOW	0x080
> +#define VIRTIO_MMIO_QUEUE_DESC_HIGH	0x084
> +
> +/* Selected queue's Available Ring address, 64 bits in two halves */
> +#define VIRTIO_MMIO_QUEUE_AVAIL_LOW	0x090
> +#define VIRTIO_MMIO_QUEUE_AVAIL_HIGH	0x094
> +
> +/* Selected queue's Used Ring address, 64 bits in two halves */
> +#define VIRTIO_MMIO_QUEUE_USED_LOW	0x0a0
> +#define VIRTIO_MMIO_QUEUE_USED_HIGH	0x0a4
> +
> +/* Configuration atomicity value */
> +#define VIRTIO_MMIO_CONFIG_GENERATION	0x0fc
> +
>  /* The config space is defined by each driver as
>   * the per-driver configuration space - Read Write */
>  #define VIRTIO_MMIO_CONFIG		0x100
> -- 
> 2.1.0

Rusty Russell

2015-Jan-21 06:05 UTC

head link

[PATCH v2] virtio-mmio: Update the device to OASIS spec version

"Michael S. Tsirkin" <mst at redhat.com>
writes:> On Tue, Jan 20, 2015 at 06:12:11PM +0000, Pawel Moll wrote:
>> This patch add a support for second version of the virtio-mmio device,
>> which follows OASIS "Virtual I/O Device (VIRTIO) Version 1.0"
>> specification.
OK, applied this instead :)

I'll leave it in my pending queue for a few days in case there's a v3.

Thanks,
Rusty.

Christopher Covington

2015-Apr-28 21:06 UTC

head link

[PATCH v2] virtio-mmio: Update the device to OASIS spec version

Hi,

On 01/20/2015 01:12 PM, Pawel Moll wrote:
> @@ -356,13 +346,6 @@ static struct virtqueue *vm_setup_vq(struct
virtio_device *vdev, unsigned index,
>  		info->num /= 2;
>  	}
>  
> -	/* Activate the queue */
> -	writel(info->num, vm_dev->base + VIRTIO_MMIO_QUEUE_NUM);
> -	writel(VIRTIO_MMIO_VRING_ALIGN,
> -			vm_dev->base + VIRTIO_MMIO_QUEUE_ALIGN);
> -	writel(virt_to_phys(info->queue) >> PAGE_SHIFT,
> -			vm_dev->base + VIRTIO_MMIO_QUEUE_PFN);
> -
>  	/* Create the vring */
>  	vq = vring_new_virtqueue(index, info->num, VIRTIO_MMIO_VRING_ALIGN,
vdev,
>  				 true, info->queue, vm_notify, callback, name);
> @@ -371,6 +354,33 @@ static struct virtqueue *vm_setup_vq(struct
virtio_device *vdev, unsigned index,
>  		goto error_new_virtqueue;
>  	}
>  
> +	/* Activate the queue */
> +	writel(info->num, vm_dev->base + VIRTIO_MMIO_QUEUE_NUM);
> +	if (vm_dev->version == 1) {
> +		writel(PAGE_SIZE, vm_dev->base + VIRTIO_MMIO_QUEUE_ALIGN);
> +		writel(virt_to_phys(info->queue) >> PAGE_SHIFT,
> +				vm_dev->base + VIRTIO_MMIO_QUEUE_PFN);
> +	} else {
> +		u64 addr;
> +
> +		addr = virt_to_phys(info->queue);
> +		writel((u32)addr, vm_dev->base + VIRTIO_MMIO_QUEUE_DESC_LOW);
> +		writel((u32)(addr >> 32),
> +				vm_dev->base + VIRTIO_MMIO_QUEUE_DESC_HIGH);
> +
> +		addr = virt_to_phys(virtqueue_get_avail(vq));
> +		writel((u32)addr, vm_dev->base + VIRTIO_MMIO_QUEUE_AVAIL_LOW);
> +		writel((u32)(addr >> 32),
> +				vm_dev->base + VIRTIO_MMIO_QUEUE_AVAIL_HIGH);
> +
> +		addr = virt_to_phys(virtqueue_get_used(vq));
> +		writel((u32)addr, vm_dev->base + VIRTIO_MMIO_QUEUE_USED_LOW);
> +		writel((u32)(addr >> 32),
> +				vm_dev->base + VIRTIO_MMIO_QUEUE_USED_HIGH);
> +
> +		writel(1, vm_dev->base + VIRTIO_MMIO_QUEUE_READY);
> +	}
> +
>  	vq->priv = info;
>  	info->vq = vq;
This patch moved the call to vring_new_virtqueue() in the legacy code flow
before the VIRTIO_MMIO_QUEUE_NUM, VIRTIO_MMIO_QUEUE_ALIGN, and
VIRTIO_MMIO_QUEUE_PFN writes. Was this intentional? Could the old behavior be
reinstated?

We have an implementation that relies on knowing ahead of time what address
range will be used, and is blind to memory accesses that occur before
VIRTIO_MMIO_QUEUE_PFN is written to (or VIRTIO_MMIO_QUEUE_READY when we
upgrade). Is such an implementation supported by the specification? We can't
find any explicit mention that the driver is forbidden from writing to the
memory region before VIRTIO_MMIO_QUEUE_READY is set to 1 (or
VIRTIO_MMIO_QUEUE_PFN is set for legacy devices).

Thanks,
Chris

-- 
Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project

Pawel Moll

2015-Apr-29 16:30 UTC

head link

[PATCH v2] virtio-mmio: Update the device to OASIS spec version

On Tue, 2015-04-28 at 22:06 +0100, Christopher Covington
wrote:> Hi,
> 
> On 01/20/2015 01:12 PM, Pawel Moll wrote:
> 
> > @@ -356,13 +346,6 @@ static struct virtqueue *vm_setup_vq(struct
virtio_device *vdev, unsigned index,
> >  		info->num /= 2;
> >  	}
> >  
> > -	/* Activate the queue */
> > -	writel(info->num, vm_dev->base + VIRTIO_MMIO_QUEUE_NUM);
> > -	writel(VIRTIO_MMIO_VRING_ALIGN,
> > -			vm_dev->base + VIRTIO_MMIO_QUEUE_ALIGN);
> > -	writel(virt_to_phys(info->queue) >> PAGE_SHIFT,
> > -			vm_dev->base + VIRTIO_MMIO_QUEUE_PFN);
> > -
> >  	/* Create the vring */
> >  	vq = vring_new_virtqueue(index, info->num,
VIRTIO_MMIO_VRING_ALIGN, vdev,
> >  				 true, info->queue, vm_notify, callback, name);
> > @@ -371,6 +354,33 @@ static struct virtqueue *vm_setup_vq(struct
virtio_device *vdev, unsigned index,
> >  		goto error_new_virtqueue;
> >  	}
> >  
> > +	/* Activate the queue */
> > +	writel(info->num, vm_dev->base + VIRTIO_MMIO_QUEUE_NUM);
> > +	if (vm_dev->version == 1) {
> > +		writel(PAGE_SIZE, vm_dev->base + VIRTIO_MMIO_QUEUE_ALIGN);
> > +		writel(virt_to_phys(info->queue) >> PAGE_SHIFT,
> > +				vm_dev->base + VIRTIO_MMIO_QUEUE_PFN);
> > +	} else {
> > +		u64 addr;
> > +
> > +		addr = virt_to_phys(info->queue);
> > +		writel((u32)addr, vm_dev->base + VIRTIO_MMIO_QUEUE_DESC_LOW);
> > +		writel((u32)(addr >> 32),
> > +				vm_dev->base + VIRTIO_MMIO_QUEUE_DESC_HIGH);
> > +
> > +		addr = virt_to_phys(virtqueue_get_avail(vq));
> > +		writel((u32)addr, vm_dev->base + VIRTIO_MMIO_QUEUE_AVAIL_LOW);
> > +		writel((u32)(addr >> 32),
> > +				vm_dev->base + VIRTIO_MMIO_QUEUE_AVAIL_HIGH);
> > +
> > +		addr = virt_to_phys(virtqueue_get_used(vq));
> > +		writel((u32)addr, vm_dev->base + VIRTIO_MMIO_QUEUE_USED_LOW);
> > +		writel((u32)(addr >> 32),
> > +				vm_dev->base + VIRTIO_MMIO_QUEUE_USED_HIGH);
> > +
> > +		writel(1, vm_dev->base + VIRTIO_MMIO_QUEUE_READY);
> > +	}
> > +
> >  	vq->priv = info;
> >  	info->vq = vq;
> 
> This patch moved the call to vring_new_virtqueue() in the legacy code flow
> before the VIRTIO_MMIO_QUEUE_NUM, VIRTIO_MMIO_QUEUE_ALIGN, and
> VIRTIO_MMIO_QUEUE_PFN writes. 
Just to make sure: we're talking the legacy case only here, correct?
> Was this intentional? 
Yes, it simply made the code cleaner. I remember stopping for a moment
doing this change and thinking what bad can it make. Haven't figured out
anything, but it seems I was wrong ;-)
> Could the old behavior be reinstated?
I see no big problem with this, but only for the "if (vm_dev->version
=1)" case.
> We have an implementation that relies on knowing ahead of time what address
> range will be used, and is blind to memory accesses that occur before
> VIRTIO_MMIO_QUEUE_PFN is written to (or VIRTIO_MMIO_QUEUE_READY when we
> upgrade). Is such an implementation supported by the specification? We
can't
> find any explicit mention that the driver is forbidden from writing to the
> memory region before VIRTIO_MMIO_QUEUE_READY is set to 1 (or
> VIRTIO_MMIO_QUEUE_PFN is set for legacy devices).
Hm. At the first glance I wouldn't expect the spec to impose such ban.
After all the driver is responsible for providing the ring memory, spec
doesn't care (or does it?) how is it coming into existence - it's the
guest's memory after all. Am I missing something obvious?

Pawel

Reasonably Related Threads

Search for more reasonably related threads

Linux Virtualization - Jan 2015 - [PATCH v2] virtio-mmio: Update the device to OASIS spec version

[PATCH v2] virtio-mmio: Update the device to OASIS spec version

[PATCH v2] virtio-mmio: Update the device to OASIS spec version

[PATCH v2] virtio-mmio: Update the device to OASIS spec version

[PATCH v2] virtio-mmio: Update the device to OASIS spec version

[PATCH v2] virtio-mmio: Update the device to OASIS spec version

Reasonably Related Threads