RE: [PATCH v2] KVM: Expose the split lock detection feature to guest VM
From: Liu, Jingqi
Date: Fri Jul 06 2018 - 04:14:07 EST
On 04/07/2018 21:37, Paolo Bonzini wrote:
> On 04/07/2018 15:06, Jingqi Liu wrote:
> > A new control bit(bit 29) in the TEST_CTRL MSR will be introduced to
> > enable detection of split locks.
> > When bit 29 of the TEST_CTRL(33H) MSR is set, the processor causes an
> > #AC exception to be issued instead of suppressing LOCK on bus(during
> > split lock access). A previous control bit (bit 31) in this MSR causes
> > the processor to disable LOCK# assertion for split locked accesses
> > when set. When bits 29 and 31 are both set, bit 29 takes precedence.
> > The release document ref below link:
> > https://software.intel.com/sites/default/files/managed/c5/15/\
> > architecture-instruction-set-extensions-programming-reference.pdf
> > This patch has a dependency on https://lkml.org/lkml/2018/5/27/78.
> > Signed-off-by: Jingqi Liu <jingqi.liu@xxxxxxxxx>
> > ---
> > arch/x86/include/asm/kvm_host.h | 1 +
> > arch/x86/kvm/vmx.c | 77
> > arch/x86/kvm/x86.c | 10 ++++++
> > arch/x86/kvm/x86.h | 5 +++
> > include/uapi/linux/kvm.h | 1 +
> > 5 files changed, 94 insertions(+)
> Checking for split lock is done with the MSR_TEST_CTL too, so you should not
> use a capability to expose the availability to KVM userspace.
> Instead you should expose the contents of MSR_TEST_CTL on the host, in a
> similar way to https://marc.info/?l=kvm&m=152998661713547&w=2.
> Please coordinate with Robert Hu on the QEMU patches too, because he's
> working on the infrastructure to use KVM_GET_MSR_FEATURE_INDEX_LIST in
Thanks for your review, had synced with Robert.
Need to work out a way, not impact on the old infrastructure.