[PATCH v2 0/3] xen/virtio: support grant based virtio on x86

[PATCH v2 0/3] xen/virtio: support grant based virtio on x86

[Juergen Gross]

Add basic support for virtio with grants on x86 by defaulting the
backend to be in dom0 in the case the guest kernel was built with
CONFIG_XEN_VIRTIO_FORCE_GRANT.

Juergen Gross (3):
  xen/virtio: restructure xen grant dma setup
  xen/virtio: use dom0 as default backend for
    CONFIG_XEN_VIRTIO_FORCE_GRANT
  xen/virtio: enable grant based virtio on x86

 arch/x86/xen/enlighten_hvm.c |  2 +-
 arch/x86/xen/enlighten_pv.c  |  2 +-
 drivers/xen/grant-dma-ops.c  | 83 +++++++++++++++++++++++++-----------
 include/xen/xen-ops.h        |  6 +++
 4 files changed, 65 insertions(+), 28 deletions(-)

-- 
2.35.3

[PATCH v2 1/3] xen/virtio: restructure xen grant dma setup

[Juergen Gross]

In order to prepare supporting other means than device tree for
setting up virtio devices under Xen, restructure the functions
xen_is_grant_dma_device() and xen_grant_setup_dma_ops() a little bit.

Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
Tested-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com> # Arm64 only
Acked-by: Stefano Stabellini <sstabellini@kernel.org>
---
V2:
- rename xen_dt_grant_setup_dma_ops() (Oleksandr Tyshchenko)
---
 drivers/xen/grant-dma-ops.c | 68 +++++++++++++++++++++++--------------
 1 file changed, 43 insertions(+), 25 deletions(-)

diff --git a/drivers/xen/grant-dma-ops.c b/drivers/xen/grant-dma-ops.c
index 8973fc1e9ccc..646ca913c05c 100644
--- a/drivers/xen/grant-dma-ops.c
+++ b/drivers/xen/grant-dma-ops.c
@@ -273,22 +273,28 @@ static const struct dma_map_ops xen_grant_dma_ops = {
 	.dma_supported = xen_grant_dma_supported,
 };
 
-bool xen_is_grant_dma_device(struct device *dev)
+static bool xen_is_dt_grant_dma_device(struct device *dev)
 {
 	struct device_node *iommu_np;
 	bool has_iommu;
 
-	/* XXX Handle only DT devices for now */
-	if (!dev->of_node)
-		return false;
-
 	iommu_np = of_parse_phandle(dev->of_node, "iommus", 0);
-	has_iommu = iommu_np && of_device_is_compatible(iommu_np, "xen,grant-dma");
+	has_iommu = iommu_np &&
+		    of_device_is_compatible(iommu_np, "xen,grant-dma");
 	of_node_put(iommu_np);
 
 	return has_iommu;
 }
 
+bool xen_is_grant_dma_device(struct device *dev)
+{
+	/* XXX Handle only DT devices for now */
+	if (dev->of_node)
+		return xen_is_dt_grant_dma_device(dev);
+
+	return false;
+}
+
 bool xen_virtio_mem_acc(struct virtio_device *dev)
 {
 	if (IS_ENABLED(CONFIG_XEN_VIRTIO_FORCE_GRANT))
@@ -297,45 +303,56 @@ bool xen_virtio_mem_acc(struct virtio_device *dev)
 	return xen_is_grant_dma_device(dev->dev.parent);
 }
 
-void xen_grant_setup_dma_ops(struct device *dev)
+static int xen_dt_grant_init_backend_domid(struct device *dev,
+					   struct xen_grant_dma_data *data)
 {
-	struct xen_grant_dma_data *data;
 	struct of_phandle_args iommu_spec;
 
-	data = find_xen_grant_dma_data(dev);
-	if (data) {
-		dev_err(dev, "Xen grant DMA data is already created\n");
-		return;
-	}
-
-	/* XXX ACPI device unsupported for now */
-	if (!dev->of_node)
-		goto err;
-
 	if (of_parse_phandle_with_args(dev->of_node, "iommus", "#iommu-cells",
 			0, &iommu_spec)) {
 		dev_err(dev, "Cannot parse iommus property\n");
-		goto err;
+		return -ESRCH;
 	}
 
 	if (!of_device_is_compatible(iommu_spec.np, "xen,grant-dma") ||
 			iommu_spec.args_count != 1) {
 		dev_err(dev, "Incompatible IOMMU node\n");
 		of_node_put(iommu_spec.np);
-		goto err;
+		return -ESRCH;
 	}
 
 	of_node_put(iommu_spec.np);
 
+	/*
+	 * The endpoint ID here means the ID of the domain where the
+	 * corresponding backend is running
+	 */
+	data->backend_domid = iommu_spec.args[0];
+
+	return 0;
+}
+
+void xen_grant_setup_dma_ops(struct device *dev)
+{
+	struct xen_grant_dma_data *data;
+
+	data = find_xen_grant_dma_data(dev);
+	if (data) {
+		dev_err(dev, "Xen grant DMA data is already created\n");
+		return;
+	}
+
 	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
 	if (!data)
 		goto err;
 
-	/*
-	 * The endpoint ID here means the ID of the domain where the corresponding
-	 * backend is running
-	 */
-	data->backend_domid = iommu_spec.args[0];
+	if (dev->of_node) {
+		if (xen_dt_grant_init_backend_domid(dev, data))
+			goto err;
+	} else {
+		/* XXX ACPI device unsupported for now */
+		goto err;
+	}
 
 	if (xa_err(xa_store(&xen_grant_dma_devices, (unsigned long)dev, data,
 			GFP_KERNEL))) {
@@ -348,6 +365,7 @@ void xen_grant_setup_dma_ops(struct device *dev)
 	return;
 
 err:
+	devm_kfree(dev, data);
 	dev_err(dev, "Cannot set up Xen grant DMA ops, retain platform DMA ops\n");
 }
 
-- 
2.35.3

[PATCH v2 2/3] xen/virtio: use dom0 as default backend for CONFIG_XEN_VIRTIO_FORCE_GRANT

[Juergen Gross]

With CONFIG_XEN_VIRTIO_FORCE_GRANT set the default backend domid to 0,
enabling to use xen_grant_dma_ops for those devices.

Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
Acked-by: Stefano Stabellini <sstabellini@kernel.org>
---
 drivers/xen/grant-dma-ops.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/xen/grant-dma-ops.c b/drivers/xen/grant-dma-ops.c
index 646ca913c05c..c703b77b33c9 100644
--- a/drivers/xen/grant-dma-ops.c
+++ b/drivers/xen/grant-dma-ops.c
@@ -349,6 +349,9 @@ void xen_grant_setup_dma_ops(struct device *dev)
 	if (dev->of_node) {
 		if (xen_dt_grant_init_backend_domid(dev, data))
 			goto err;
+	} else if (IS_ENABLED(CONFIG_XEN_VIRTIO_FORCE_GRANT)) {
+		dev_info(dev, "Using dom0 as backend\n");
+		data->backend_domid = 0;
 	} else {
 		/* XXX ACPI device unsupported for now */
 		goto err;
-- 
2.35.3

[PATCH v2 3/3] xen/virtio: enable grant based virtio on x86

[Juergen Gross]

Use an x86-specific virtio_check_mem_acc_cb() for Xen in order to setup
the correct DMA ops.

Signed-off-by: Juergen Gross <jgross@suse.com>
---
V2:
- add missing PV check in xen_virtio_mem_acc() (Oleksandr Tyshchenko)
- add xen_virtio_restricted_mem_acc() stub (Oleksandr Tyshchenko)
---
 arch/x86/xen/enlighten_hvm.c |  2 +-
 arch/x86/xen/enlighten_pv.c  |  2 +-
 drivers/xen/grant-dma-ops.c  | 12 +++++++++++-
 include/xen/xen-ops.h        |  6 ++++++
 4 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/arch/x86/xen/enlighten_hvm.c b/arch/x86/xen/enlighten_hvm.c
index 1c1ac418484b..c1cd28e915a3 100644
--- a/arch/x86/xen/enlighten_hvm.c
+++ b/arch/x86/xen/enlighten_hvm.c
@@ -212,7 +212,7 @@ static void __init xen_hvm_guest_init(void)
 		return;
 
 	if (IS_ENABLED(CONFIG_XEN_VIRTIO_FORCE_GRANT))
-		virtio_set_mem_acc_cb(virtio_require_restricted_mem_acc);
+		virtio_set_mem_acc_cb(xen_virtio_restricted_mem_acc);
 
 	init_hvm_pv_info();
 
diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c
index 9b1a58dda935..45b24c1b646a 100644
--- a/arch/x86/xen/enlighten_pv.c
+++ b/arch/x86/xen/enlighten_pv.c
@@ -112,7 +112,7 @@ static void __init xen_pv_init_platform(void)
 {
 	/* PV guests can't operate virtio devices without grants. */
 	if (IS_ENABLED(CONFIG_XEN_VIRTIO))
-		virtio_set_mem_acc_cb(virtio_require_restricted_mem_acc);
+		virtio_set_mem_acc_cb(xen_virtio_restricted_mem_acc);
 
 	populate_extra_pte(fix_to_virt(FIX_PARAVIRT_BOOTMAP));
 
diff --git a/drivers/xen/grant-dma-ops.c b/drivers/xen/grant-dma-ops.c
index c703b77b33c9..63c3f0dac066 100644
--- a/drivers/xen/grant-dma-ops.c
+++ b/drivers/xen/grant-dma-ops.c
@@ -297,7 +297,7 @@ bool xen_is_grant_dma_device(struct device *dev)
 
 bool xen_virtio_mem_acc(struct virtio_device *dev)
 {
-	if (IS_ENABLED(CONFIG_XEN_VIRTIO_FORCE_GRANT))
+	if (IS_ENABLED(CONFIG_XEN_VIRTIO_FORCE_GRANT) || xen_pv_domain())
 		return true;
 
 	return xen_is_grant_dma_device(dev->dev.parent);
@@ -372,6 +372,16 @@ void xen_grant_setup_dma_ops(struct device *dev)
 	dev_err(dev, "Cannot set up Xen grant DMA ops, retain platform DMA ops\n");
 }
 
+bool xen_virtio_restricted_mem_acc(struct virtio_device *dev)
+{
+	bool ret = xen_virtio_mem_acc(dev);
+
+	if (ret)
+		xen_grant_setup_dma_ops(dev->dev.parent);
+
+	return ret;
+}
+
 MODULE_DESCRIPTION("Xen grant DMA-mapping layer");
 MODULE_AUTHOR("Juergen Gross <jgross@suse.com>");
 MODULE_LICENSE("GPL");
diff --git a/include/xen/xen-ops.h b/include/xen/xen-ops.h
index dae0f350c678..a34f4271a2e9 100644
--- a/include/xen/xen-ops.h
+++ b/include/xen/xen-ops.h
@@ -219,6 +219,7 @@ static inline void xen_preemptible_hcall_end(void) { }
 void xen_grant_setup_dma_ops(struct device *dev);
 bool xen_is_grant_dma_device(struct device *dev);
 bool xen_virtio_mem_acc(struct virtio_device *dev);
+bool xen_virtio_restricted_mem_acc(struct virtio_device *dev);
 #else
 static inline void xen_grant_setup_dma_ops(struct device *dev)
 {
@@ -234,6 +235,11 @@ static inline bool xen_virtio_mem_acc(struct virtio_device *dev)
 {
 	return false;
 }
+
+static inline bool xen_virtio_restricted_mem_acc(struct virtio_device *dev)
+{
+	return false;
+}
 #endif /* CONFIG_XEN_GRANT_DMA_OPS */
 
 #endif /* INCLUDE_XEN_OPS_H */
-- 
2.35.3

Re: [PATCH v2 3/3] xen/virtio: enable grant based virtio on x86

[Oleksandr Tyshchenko]

On 07.10.22 09:41, Juergen Gross wrote:

Hello Juergen

> Use an x86-specific virtio_check_mem_acc_cb() for Xen in order to setup
> the correct DMA ops.
>
> Signed-off-by: Juergen Gross <jgross@suse.com>
> ---
> V2:
> - add missing PV check in xen_virtio_mem_acc() (Oleksandr Tyshchenko)
> - add xen_virtio_restricted_mem_acc() stub (Oleksandr Tyshchenko)


Reviewed-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com> # 
common code


> ---
>   arch/x86/xen/enlighten_hvm.c |  2 +-
>   arch/x86/xen/enlighten_pv.c  |  2 +-
>   drivers/xen/grant-dma-ops.c  | 12 +++++++++++-
>   include/xen/xen-ops.h        |  6 ++++++
>   4 files changed, 19 insertions(+), 3 deletions(-)
>
> diff --git a/arch/x86/xen/enlighten_hvm.c b/arch/x86/xen/enlighten_hvm.c
> index 1c1ac418484b..c1cd28e915a3 100644
> --- a/arch/x86/xen/enlighten_hvm.c
> +++ b/arch/x86/xen/enlighten_hvm.c
> @@ -212,7 +212,7 @@ static void __init xen_hvm_guest_init(void)
>   		return;
>   
>   	if (IS_ENABLED(CONFIG_XEN_VIRTIO_FORCE_GRANT))
> -		virtio_set_mem_acc_cb(virtio_require_restricted_mem_acc);
> +		virtio_set_mem_acc_cb(xen_virtio_restricted_mem_acc);
>   
>   	init_hvm_pv_info();
>   
> diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c
> index 9b1a58dda935..45b24c1b646a 100644
> --- a/arch/x86/xen/enlighten_pv.c
> +++ b/arch/x86/xen/enlighten_pv.c
> @@ -112,7 +112,7 @@ static void __init xen_pv_init_platform(void)
>   {
>   	/* PV guests can't operate virtio devices without grants. */
>   	if (IS_ENABLED(CONFIG_XEN_VIRTIO))
> -		virtio_set_mem_acc_cb(virtio_require_restricted_mem_acc);
> +		virtio_set_mem_acc_cb(xen_virtio_restricted_mem_acc);
>   
>   	populate_extra_pte(fix_to_virt(FIX_PARAVIRT_BOOTMAP));
>   
> diff --git a/drivers/xen/grant-dma-ops.c b/drivers/xen/grant-dma-ops.c
> index c703b77b33c9..63c3f0dac066 100644
> --- a/drivers/xen/grant-dma-ops.c
> +++ b/drivers/xen/grant-dma-ops.c
> @@ -297,7 +297,7 @@ bool xen_is_grant_dma_device(struct device *dev)
>   
>   bool xen_virtio_mem_acc(struct virtio_device *dev)
>   {
> -	if (IS_ENABLED(CONFIG_XEN_VIRTIO_FORCE_GRANT))
> +	if (IS_ENABLED(CONFIG_XEN_VIRTIO_FORCE_GRANT) || xen_pv_domain())
>   		return true;
>   
>   	return xen_is_grant_dma_device(dev->dev.parent);
> @@ -372,6 +372,16 @@ void xen_grant_setup_dma_ops(struct device *dev)
>   	dev_err(dev, "Cannot set up Xen grant DMA ops, retain platform DMA ops\n");
>   }
>   
> +bool xen_virtio_restricted_mem_acc(struct virtio_device *dev)
> +{
> +	bool ret = xen_virtio_mem_acc(dev);
> +
> +	if (ret)
> +		xen_grant_setup_dma_ops(dev->dev.parent);
> +
> +	return ret;
> +}
> +
>   MODULE_DESCRIPTION("Xen grant DMA-mapping layer");
>   MODULE_AUTHOR("Juergen Gross <jgross@suse.com>");
>   MODULE_LICENSE("GPL");
> diff --git a/include/xen/xen-ops.h b/include/xen/xen-ops.h
> index dae0f350c678..a34f4271a2e9 100644
> --- a/include/xen/xen-ops.h
> +++ b/include/xen/xen-ops.h
> @@ -219,6 +219,7 @@ static inline void xen_preemptible_hcall_end(void) { }
>   void xen_grant_setup_dma_ops(struct device *dev);
>   bool xen_is_grant_dma_device(struct device *dev);
>   bool xen_virtio_mem_acc(struct virtio_device *dev);
> +bool xen_virtio_restricted_mem_acc(struct virtio_device *dev);
>   #else
>   static inline void xen_grant_setup_dma_ops(struct device *dev)
>   {
> @@ -234,6 +235,11 @@ static inline bool xen_virtio_mem_acc(struct virtio_device *dev)
>   {
>   	return false;
>   }
> +
> +static inline bool xen_virtio_restricted_mem_acc(struct virtio_device *dev)
> +{
> +	return false;
> +}
>   #endif /* CONFIG_XEN_GRANT_DMA_OPS */
>   
>   #endif /* INCLUDE_XEN_OPS_H */

-- 
Regards,

Oleksandr Tyshchenko

Re: [PATCH v2 3/3] xen/virtio: enable grant based virtio on x86

[Boris Ostrovsky]

On 10/7/22 10:00 AM, Oleksandr Tyshchenko wrote:
> On 07.10.22 09:41, Juergen Gross wrote:
>
> Hello Juergen
>
>> Use an x86-specific virtio_check_mem_acc_cb() for Xen in order to setup
>> the correct DMA ops.
>>
>> Signed-off-by: Juergen Gross <jgross@suse.com>
>> ---
>> V2:
>> - add missing PV check in xen_virtio_mem_acc() (Oleksandr Tyshchenko)
>> - add xen_virtio_restricted_mem_acc() stub (Oleksandr Tyshchenko)
>
> Reviewed-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com> #
> common code



Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>