diff options
Diffstat (limited to 'Documentation/virt')
| -rw-r--r-- | Documentation/virt/kvm/api.rst | 41 | ||||
| -rw-r--r-- | Documentation/virt/kvm/arm/pvtime.rst | 14 | ||||
| -rw-r--r-- | Documentation/virt/kvm/devices/arm-vgic-its.rst | 5 | ||||
| -rw-r--r-- | Documentation/virt/kvm/devices/vcpu.rst | 2 |
4 files changed, 45 insertions, 17 deletions
diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst index 9175d41e8081..fbb9a22030ba 100644 --- a/Documentation/virt/kvm/api.rst +++ b/Documentation/virt/kvm/api.rst @@ -7418,8 +7418,9 @@ hibernation of the host; however the VMM needs to manually save/restore the tags as appropriate if the VM is migrated. When this capability is enabled all memory in memslots must be mapped as -not-shareable (no MAP_SHARED), attempts to create a memslot with a -MAP_SHARED mmap will result in an -EINVAL return. +``MAP_ANONYMOUS`` or with a RAM-based file mapping (``tmpfs``, ``memfd``), +attempts to create a memslot with an invalid mmap will result in an +-EINVAL return. When enabled the VMM may make use of the ``KVM_ARM_MTE_COPY_TAGS`` ioctl to perform a bulk copy of tags to/from the guest. @@ -7954,7 +7955,7 @@ regardless of what has actually been exposed through the CPUID leaf. 8.29 KVM_CAP_DIRTY_LOG_RING/KVM_CAP_DIRTY_LOG_RING_ACQ_REL ---------------------------------------------------------- -:Architectures: x86 +:Architectures: x86, arm64 :Parameters: args[0] - size of the dirty log ring KVM is capable of tracking dirty memory using ring buffers that are @@ -8036,13 +8037,6 @@ flushing is done by the KVM_GET_DIRTY_LOG ioctl). To achieve that, one needs to kick the vcpu out of KVM_RUN using a signal. The resulting vmexit ensures that all dirty GFNs are flushed to the dirty rings. -NOTE: the capability KVM_CAP_DIRTY_LOG_RING and the corresponding -ioctl KVM_RESET_DIRTY_RINGS are mutual exclusive to the existing ioctls -KVM_GET_DIRTY_LOG and KVM_CLEAR_DIRTY_LOG. After enabling -KVM_CAP_DIRTY_LOG_RING with an acceptable dirty ring size, the virtual -machine will switch to ring-buffer dirty page tracking and further -KVM_GET_DIRTY_LOG or KVM_CLEAR_DIRTY_LOG ioctls will fail. - NOTE: KVM_CAP_DIRTY_LOG_RING_ACQ_REL is the only capability that should be exposed by weakly ordered architecture, in order to indicate the additional memory ordering requirements imposed on userspace when @@ -8051,6 +8045,33 @@ Architecture with TSO-like ordering (such as x86) are allowed to expose both KVM_CAP_DIRTY_LOG_RING and KVM_CAP_DIRTY_LOG_RING_ACQ_REL to userspace. +After enabling the dirty rings, the userspace needs to detect the +capability of KVM_CAP_DIRTY_LOG_RING_WITH_BITMAP to see whether the +ring structures can be backed by per-slot bitmaps. With this capability +advertised, it means the architecture can dirty guest pages without +vcpu/ring context, so that some of the dirty information will still be +maintained in the bitmap structure. KVM_CAP_DIRTY_LOG_RING_WITH_BITMAP +can't be enabled if the capability of KVM_CAP_DIRTY_LOG_RING_ACQ_REL +hasn't been enabled, or any memslot has been existing. + +Note that the bitmap here is only a backup of the ring structure. The +use of the ring and bitmap combination is only beneficial if there is +only a very small amount of memory that is dirtied out of vcpu/ring +context. Otherwise, the stand-alone per-slot bitmap mechanism needs to +be considered. + +To collect dirty bits in the backup bitmap, userspace can use the same +KVM_GET_DIRTY_LOG ioctl. KVM_CLEAR_DIRTY_LOG isn't needed as long as all +the generation of the dirty bits is done in a single pass. Collecting +the dirty bitmap should be the very last thing that the VMM does before +considering the state as complete. VMM needs to ensure that the dirty +state is final and avoid missing dirty pages from another ioctl ordered +after the bitmap collection. + +NOTE: One example of using the backup bitmap is saving arm64 vgic/its +tables through KVM_DEV_ARM_{VGIC_GRP_CTRL, ITS_SAVE_TABLES} command on +KVM device "kvm-arm-vgic-its" when dirty ring is enabled. + 8.30 KVM_CAP_XEN_HVM -------------------- diff --git a/Documentation/virt/kvm/arm/pvtime.rst b/Documentation/virt/kvm/arm/pvtime.rst index 392521af7c90..e88b34e586be 100644 --- a/Documentation/virt/kvm/arm/pvtime.rst +++ b/Documentation/virt/kvm/arm/pvtime.rst @@ -23,21 +23,23 @@ the PV_TIME_FEATURES hypercall should be probed using the SMCCC 1.1 ARCH_FEATURES mechanism before calling it. PV_TIME_FEATURES - ============= ======== ========== + + ============= ======== ================================================= Function ID: (uint32) 0xC5000020 PV_call_id: (uint32) The function to query for support. Currently only PV_TIME_ST is supported. Return value: (int64) NOT_SUPPORTED (-1) or SUCCESS (0) if the relevant PV-time feature is supported by the hypervisor. - ============= ======== ========== + ============= ======== ================================================= PV_TIME_ST - ============= ======== ========== + + ============= ======== ============================================== Function ID: (uint32) 0xC5000021 Return value: (int64) IPA of the stolen time data structure for this VCPU. On failure: NOT_SUPPORTED (-1) - ============= ======== ========== + ============= ======== ============================================== The IPA returned by PV_TIME_ST should be mapped by the guest as normal memory with inner and outer write back caching attributes, in the inner shareable @@ -76,5 +78,5 @@ It is advisable that one or more 64k pages are set aside for the purpose of these structures and not used for other purposes, this enables the guest to map the region using 64k pages and avoids conflicting attributes with other memory. -For the user space interface see Documentation/virt/kvm/devices/vcpu.rst -section "3. GROUP: KVM_ARM_VCPU_PVTIME_CTRL". +For the user space interface see +:ref:`Documentation/virt/kvm/devices/vcpu.rst <kvm_arm_vcpu_pvtime_ctrl>`.
\ No newline at end of file diff --git a/Documentation/virt/kvm/devices/arm-vgic-its.rst b/Documentation/virt/kvm/devices/arm-vgic-its.rst index d257eddbae29..e053124f77c4 100644 --- a/Documentation/virt/kvm/devices/arm-vgic-its.rst +++ b/Documentation/virt/kvm/devices/arm-vgic-its.rst @@ -52,7 +52,10 @@ KVM_DEV_ARM_VGIC_GRP_CTRL KVM_DEV_ARM_ITS_SAVE_TABLES save the ITS table data into guest RAM, at the location provisioned - by the guest in corresponding registers/table entries. + by the guest in corresponding registers/table entries. Should userspace + require a form of dirty tracking to identify which pages are modified + by the saving process, it should use a bitmap even if using another + mechanism to track the memory dirtied by the vCPUs. The layout of the tables in guest memory defines an ABI. The entries are laid out in little endian format as described in the last paragraph. diff --git a/Documentation/virt/kvm/devices/vcpu.rst b/Documentation/virt/kvm/devices/vcpu.rst index 716aa3edae14..31f14ec4a65b 100644 --- a/Documentation/virt/kvm/devices/vcpu.rst +++ b/Documentation/virt/kvm/devices/vcpu.rst @@ -171,6 +171,8 @@ configured values on other VCPUs. Userspace should configure the interrupt numbers on at least one VCPU after creating all VCPUs and before running any VCPUs. +.. _kvm_arm_vcpu_pvtime_ctrl: + 3. GROUP: KVM_ARM_VCPU_PVTIME_CTRL ================================== |