From 54f39aa8cb0a870de6ec36bb0eb8f479f97d7fec Mon Sep 17 00:00:00 2001
From: Sebastien Boeuf <sebastien.boeuf@intel.com>
Date: Thu, 5 May 2022 11:00:07 +0200
Subject: [PATCH] vmm: Validate vhost-user-block/net are not configured with
 iommu=on

Extend the validate() function for both DiskConfig and NetConfig so that
we return an error if a vhost-user-block or vhost-user-net device is
expected to be placed behind the virtual IOMMU. Since these devices
don't support this feature, we can't allow iommu to be set to true in
these cases.

Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
---
 vmm/src/config.rs | 31 ++++++++++++++++++++++++-------
 1 file changed, 24 insertions(+), 7 deletions(-)

diff --git a/vmm/src/config.rs b/vmm/src/config.rs
index 3a601728b..480002348 100644
--- a/vmm/src/config.rs
+++ b/vmm/src/config.rs
@@ -169,11 +169,13 @@ pub enum ValidationError {
     /// On a IOMMU segment but not behind IOMMU
     OnIommuSegment(u16),
     // On a IOMMU segment but IOMMU not suported
-    IommuNotSupported(u16),
+    IommuNotSupportedOnSegment(u16),
     // Identifier is not unique
     IdentifierNotUnique(String),
     /// Invalid identifier
     InvalidIdentifier(String),
+    /// Placing the device behind a virtual IOMMU is not supported
+    IommuNotSupported,
 }
 
 type ValidationResult<T> = std::result::Result<T, ValidationError>;
@@ -253,10 +255,10 @@ impl fmt::Display for ValidationError {
                     pci_segment
                 )
             }
-            IommuNotSupported(pci_segment) => {
+            IommuNotSupportedOnSegment(pci_segment) => {
                 write!(
                     f,
-                    "Device is on an IOMMU PCI segment ({}) but does support being placed behind IOMMU",
+                    "Device is on an IOMMU PCI segment ({}) but does not support being placed behind IOMMU",
                     pci_segment
                 )
             }
@@ -266,6 +268,9 @@ impl fmt::Display for ValidationError {
             InvalidIdentifier(s) => {
                 write!(f, "Identifier {} is invalid", s)
             }
+            IommuNotSupported => {
+                write!(f, "Device does not support being placed behind IOMMU")
+            }
         }
     }
 }
@@ -1157,6 +1162,10 @@ impl DiskConfig {
             return Err(ValidationError::TooManyQueues);
         }
 
+        if self.vhost_user && self.iommu {
+            return Err(ValidationError::IommuNotSupported);
+        }
+
         if let Some(platform_config) = vm_config.platform.as_ref() {
             if self.pci_segment >= platform_config.num_pci_segments {
                 return Err(ValidationError::InvalidPciSegment(self.pci_segment));
@@ -1453,6 +1462,10 @@ impl NetConfig {
             return Err(ValidationError::TooManyQueues);
         }
 
+        if self.vhost_user && self.iommu {
+            return Err(ValidationError::IommuNotSupported);
+        }
+
         if let Some(platform_config) = vm_config.platform.as_ref() {
             if self.pci_segment >= platform_config.num_pci_segments {
                 return Err(ValidationError::InvalidPciSegment(self.pci_segment));
@@ -1682,7 +1695,9 @@ impl FsConfig {
 
             if let Some(iommu_segments) = platform_config.iommu_segments.as_ref() {
                 if iommu_segments.contains(&self.pci_segment) {
-                    return Err(ValidationError::IommuNotSupported(self.pci_segment));
+                    return Err(ValidationError::IommuNotSupportedOnSegment(
+                        self.pci_segment,
+                    ));
                 }
             }
         }
@@ -1971,7 +1986,9 @@ impl UserDeviceConfig {
 
             if let Some(iommu_segments) = platform_config.iommu_segments.as_ref() {
                 if iommu_segments.contains(&self.pci_segment) {
-                    return Err(ValidationError::IommuNotSupported(self.pci_segment));
+                    return Err(ValidationError::IommuNotSupportedOnSegment(
+                        self.pci_segment,
+                    ));
                 }
             }
         }
@@ -3725,7 +3742,7 @@ mod tests {
         }]);
         assert_eq!(
             invalid_config.validate(),
-            Err(ValidationError::IommuNotSupported(1))
+            Err(ValidationError::IommuNotSupportedOnSegment(1))
         );
 
         let mut invalid_config = valid_config.clone();
@@ -3756,7 +3773,7 @@ mod tests {
         }]);
         assert_eq!(
             invalid_config.validate(),
-            Err(ValidationError::IommuNotSupported(1))
+            Err(ValidationError::IommuNotSupportedOnSegment(1))
         );
     }
 }