summaryrefslogtreecommitdiffstats
path: root/Documentation/virtual
diff options
context:
space:
mode:
authorPaul Mackerras <paulus@ozlabs.org>2018-09-12 02:42:12 +0200
committerPaul Mackerras <paulus@ozlabs.org>2018-10-05 07:55:06 +0200
commitaa2278644ae54ff762ce33f9c9563d759e9cca9f (patch)
treefc55e858903a21c302862c1dc5ac5b3b46f7a6e6 /Documentation/virtual
parentKVM: PPC: Book3S PR: Exiting split hack mode needs to fixup both PC and LR (diff)
downloadlinux-aa2278644ae54ff762ce33f9c9563d759e9cca9f.tar.xz
linux-aa2278644ae54ff762ce33f9c9563d759e9cca9f.zip
KVM: PPC: Book3S HV: Provide mode where all vCPUs on a core must be the same VM
This adds a mode where the vcore scheduling logic in HV KVM limits itself to scheduling only virtual cores from the same VM on any given physical core. This is enabled via a new module parameter on the kvm-hv module called "one_vm_per_core". For this to work on POWER9, it is necessary to set indep_threads_mode=N. (On POWER8, hardware limitations mean that KVM is never in independent threads mode, regardless of the indep_threads_mode setting.) Thus the settings needed for this to work are: 1. The host is in SMT1 mode. 2. On POWER8, the host is not in 2-way or 4-way static split-core mode. 3. On POWER9, the indep_threads_mode parameter is N. 4. The one_vm_per_core parameter is Y. With these settings, KVM can run up to 4 vcpus on a core at the same time on POWER9, or up to 8 vcpus on POWER8 (depending on the guest threading mode), and will ensure that all of the vcpus belong to the same VM. This is intended for use in security-conscious settings where users are concerned about possible side-channel attacks between threads which could perhaps enable one VM to attack another VM on the same core, or the host. Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Diffstat (limited to 'Documentation/virtual')
0 files changed, 0 insertions, 0 deletions