diff mbox series

[v11,1/2] virtio: let arch advertise guest's memory access restrictions

Message ID 1599471547-28631-2-git-send-email-pmorel@linux.ibm.com (mailing list archive)
State New, archived
Headers show
Series s390: virtio: let arch validate VIRTIO features | expand

Commit Message

Pierre Morel Sept. 7, 2020, 9:39 a.m. UTC 
An architecture may restrict host access to guest memory,
e.g. IBM s390 Secure Execution or AMD SEV.

Provide a new Kconfig entry the architecture can select,
CONFIG_ARCH_HAS_RESTRICTED_VIRTIO_MEMORY_ACCESS, when it provides
the arch_has_restricted_virtio_memory_access callback to advertise
to VIRTIO common code when the architecture restricts memory access
from the host.

The common code can then fail the probe for any device where
VIRTIO_F_ACCESS_PLATFORM is required, but not set.

Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
---
 drivers/virtio/Kconfig        |  6 ++++++
 drivers/virtio/virtio.c       | 15 +++++++++++++++
 include/linux/virtio_config.h | 10 ++++++++++
 3 files changed, 31 insertions(+)

Comments

Halil Pasic Sept. 7, 2020, 10:22 p.m. UTC | #1 
On Mon,  7 Sep 2020 11:39:06 +0200
Pierre Morel <pmorel@linux.ibm.com> wrote:

> An architecture may restrict host access to guest memory,
> e.g. IBM s390 Secure Execution or AMD SEV.
> 
> Provide a new Kconfig entry the architecture can select,
> CONFIG_ARCH_HAS_RESTRICTED_VIRTIO_MEMORY_ACCESS, when it provides
> the arch_has_restricted_virtio_memory_access callback to advertise
> to VIRTIO common code when the architecture restricts memory access
> from the host.
> 
> The common code can then fail the probe for any device where
> VIRTIO_F_ACCESS_PLATFORM is required, but not set.
> 
> Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
> Reviewed-by: Cornelia Huck <cohuck@redhat.com>

Reviewed-by: Halil Pasic <pasic@linux.ibm.com>

[..]
>  
> +config ARCH_HAS_RESTRICTED_VIRTIO_MEMORY_ACCESS
> +	bool
> +	help
> +	  This option is selected if the architecture may need to enforce
> +	  VIRTIO_F_IOMMU_PLATFORM.
> +

A small nit: you use F_ACCESS_PLATFORM everywhere but here.

Regards,
Halil
diff mbox series

Patch

diff --git a/drivers/virtio/Kconfig b/drivers/virtio/Kconfig
index 5c92e4a50882..3999b411624c 100644
--- a/drivers/virtio/Kconfig
+++ b/drivers/virtio/Kconfig
@@ -6,6 +6,12 @@  config VIRTIO
 	  bus, such as CONFIG_VIRTIO_PCI, CONFIG_VIRTIO_MMIO, CONFIG_RPMSG
 	  or CONFIG_S390_GUEST.
 
+config ARCH_HAS_RESTRICTED_VIRTIO_MEMORY_ACCESS
+	bool
+	help
+	  This option is selected if the architecture may need to enforce
+	  VIRTIO_F_IOMMU_PLATFORM.
+
 menuconfig VIRTIO_MENU
 	bool "Virtio drivers"
 	default y
diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c
index a977e32a88f2..a2b3f12e10a2 100644
--- a/drivers/virtio/virtio.c
+++ b/drivers/virtio/virtio.c
@@ -176,6 +176,21 @@  int virtio_finalize_features(struct virtio_device *dev)
 	if (ret)
 		return ret;
 
+	ret = arch_has_restricted_virtio_memory_access();
+	if (ret) {
+		if (!virtio_has_feature(dev, VIRTIO_F_VERSION_1)) {
+			dev_warn(&dev->dev,
+				 "device must provide VIRTIO_F_VERSION_1\n");
+			return -ENODEV;
+		}
+
+		if (!virtio_has_feature(dev, VIRTIO_F_ACCESS_PLATFORM)) {
+			dev_warn(&dev->dev,
+				 "device must provide VIRTIO_F_ACCESS_PLATFORM\n");
+			return -ENODEV;
+		}
+	}
+
 	if (!virtio_has_feature(dev, VIRTIO_F_VERSION_1))
 		return 0;
 
diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h
index 8fe857e27ef3..3f697c8c8205 100644
--- a/include/linux/virtio_config.h
+++ b/include/linux/virtio_config.h
@@ -540,4 +540,14 @@  static inline void virtio_cwrite64(struct virtio_device *vdev,
 			virtio_cread_le((vdev), structname, member, ptr); \
 		_r;							\
 	})
+
+#ifdef CONFIG_ARCH_HAS_RESTRICTED_VIRTIO_MEMORY_ACCESS
+int arch_has_restricted_virtio_memory_access(void);
+#else
+static inline int arch_has_restricted_virtio_memory_access(void)
+{
+	return 0;
+}
+#endif /* CONFIG_ARCH_HAS_RESTRICTED_VIRTIO_MEMORY_ACCESS */
+
 #endif /* _LINUX_VIRTIO_CONFIG_H */