From: Paolo Bonzini <pbonzini@redhat.com>
To: Jingqi Liu <jingqi.liu@intel.com>
Cc: rkrcmar@redhat.com, tglx@linutronix.de, mingo@redhat.com,
hpa@zytor.com, x86@kernel.org, linux-kernel@vger.kernel.org,
kvm@vger.kernel.org, wei.w.wang@intel.com,
Robert Hoo <robert.hu@linux.intel.com>
Subject: Re: [PATCH v2] KVM: Expose the split lock detection feature to guest VM
Date: Wed, 4 Jul 2018 15:36:40 +0200 [thread overview]
Message-ID: <7813a04b-8058-538b-8c9b-cdd01ce119ac@redhat.com> (raw)
In-Reply-To: <1530709593-87702-1-git-send-email-jingqi.liu@intel.com>
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@intel.com>
> ---
> 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 QEMU.
Thanks,
Paolo
next prev parent reply other threads:[~2018-07-04 13:36 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-04 13:06 [PATCH v2] KVM: Expose the split lock detection feature to guest VM Jingqi Liu
2018-07-04 13:36 ` Paolo Bonzini [this message]
2018-07-04 14:51 ` Thomas Gleixner
2018-07-04 16:21 ` Paolo Bonzini
2018-07-04 18:39 ` Thomas Gleixner
2018-07-06 8:13 ` Liu, Jingqi
2018-07-04 23:07 ` kbuild test robot
2018-07-04 23:07 ` kbuild test robot
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