From 423873736b78f549fbfa2f715f2e4de7e6c5e1e9 Mon Sep 17 00:00:00 2001 From: Alex Williamson Date: Tue, 20 Dec 2011 21:59:03 -0700 Subject: KVM: Remove ability to assign a device without iommu support This option has no users and it exposes a security hole that we can allow devices to be assigned without iommu protection. Make KVM_DEV_ASSIGN_ENABLE_IOMMU a mandatory option. Signed-off-by: Alex Williamson Signed-off-by: Marcelo Tosatti --- Documentation/virtual/kvm/api.txt | 3 +++ 1 file changed, 3 insertions(+) (limited to 'Documentation') diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt index 7945b0b..ee2c96b 100644 --- a/Documentation/virtual/kvm/api.txt +++ b/Documentation/virtual/kvm/api.txt @@ -1151,6 +1151,9 @@ following flags are specified: /* Depends on KVM_CAP_IOMMU */ #define KVM_DEV_ASSIGN_ENABLE_IOMMU (1 << 0) +The KVM_DEV_ASSIGN_ENABLE_IOMMU flag is a mandatory option to ensure +isolation of the device. Usages not specifying this flag are deprecated. + 4.49 KVM_DEASSIGN_PCI_DEVICE Capability: KVM_CAP_DEVICE_DEASSIGNMENT -- cgit v1.1 From 3d27e23b17010c668db311140b17bbbb70c78fb9 Mon Sep 17 00:00:00 2001 From: Alex Williamson Date: Tue, 20 Dec 2011 21:59:09 -0700 Subject: KVM: Device assignment permission checks Only allow KVM device assignment to attach to devices which: - Are not bridges - Have BAR resources (assume others are special devices) - The user has permissions to use Assigning a bridge is a configuration error, it's not supported, and typically doesn't result in the behavior the user is expecting anyway. Devices without BAR resources are typically chipset components that also don't have host drivers. We don't want users to hold such devices captive or cause system problems by fencing them off into an iommu domain. We determine "permission to use" by testing whether the user has access to the PCI sysfs resource files. By default a normal user will not have access to these files, so it provides a good indication that an administration agent has granted the user access to the device. [Yang Bai: add missing #include] [avi: fix comment style] Signed-off-by: Alex Williamson Signed-off-by: Yang Bai Signed-off-by: Marcelo Tosatti --- Documentation/virtual/kvm/api.txt | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'Documentation') diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt index ee2c96b..4df9af4 100644 --- a/Documentation/virtual/kvm/api.txt +++ b/Documentation/virtual/kvm/api.txt @@ -1154,6 +1154,10 @@ following flags are specified: The KVM_DEV_ASSIGN_ENABLE_IOMMU flag is a mandatory option to ensure isolation of the device. Usages not specifying this flag are deprecated. +Only PCI header type 0 devices with PCI BAR resources are supported by +device assignment. The user requesting this ioctl must have read/write +access to the PCI sysfs resource files associated with the device. + 4.49 KVM_DEASSIGN_PCI_DEVICE Capability: KVM_CAP_DEVICE_DEASSIGNMENT -- cgit v1.1 From 4d25a066b69fb749a39d0d4c610689dd765a0b0e Mon Sep 17 00:00:00 2001 From: Jan Kiszka Date: Wed, 21 Dec 2011 12:28:29 +0100 Subject: KVM: Don't automatically expose the TSC deadline timer in cpuid Unlike all of the other cpuid bits, the TSC deadline timer bit is set unconditionally, regardless of what userspace wants. This is broken in several ways: - if userspace doesn't use KVM_CREATE_IRQCHIP, and doesn't emulate the TSC deadline timer feature, a guest that uses the feature will break - live migration to older host kernels that don't support the TSC deadline timer will cause the feature to be pulled from under the guest's feet; breaking it - guests that are broken wrt the feature will fail. Fix by not enabling the feature automatically; instead report it to userspace. Because the feature depends on KVM_CREATE_IRQCHIP, which we cannot guarantee will be called, we expose it via a KVM_CAP_TSC_DEADLINE_TIMER and not KVM_GET_SUPPORTED_CPUID. Fixes the Illumos guest kernel, which uses the TSC deadline timer feature. [avi: add the KVM_CAP + documentation] Reported-by: Alexey Zaytsev Tested-by: Alexey Zaytsev Signed-off-by: Jan Kiszka Signed-off-by: Avi Kivity --- Documentation/virtual/kvm/api.txt | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'Documentation') diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt index 4df9af4..e2a4b52 100644 --- a/Documentation/virtual/kvm/api.txt +++ b/Documentation/virtual/kvm/api.txt @@ -1100,6 +1100,15 @@ emulate them efficiently. The fields in each entry are defined as follows: eax, ebx, ecx, edx: the values returned by the cpuid instruction for this function/index combination +The TSC deadline timer feature (CPUID leaf 1, ecx[24]) is always returned +as false, since the feature depends on KVM_CREATE_IRQCHIP for local APIC +support. Instead it is reported via + + ioctl(KVM_CHECK_EXTENSION, KVM_CAP_TSC_DEADLINE_TIMER) + +if that returns true and you use KVM_CREATE_IRQCHIP, or if you emulate the +feature in userspace, then you can enable the feature for KVM_SET_CPUID2. + 4.47 KVM_PPC_GET_PVINFO Capability: KVM_CAP_PPC_GET_PVINFO -- cgit v1.1