From: Tao Xu <tao3.xu@intel.com>
To: pbonzini@redhat.com, rkrcmar@redhat.com, corbet@lwn.net,
tglx@linutronix.de, mingo@redhat.com, bp@alien8.de,
hpa@zytor.com, sean.j.christopherson@intel.com
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
fenghua.yu@intel.com, xiaoyao.li@linux.intel.com,
jingqi.liu@intel.com, tao3.xu@intel.com
Subject: [PATCH v5 0/3] KVM: x86: Enable user wait instructions
Date: Thu, 20 Jun 2019 16:46:17 +0800 [thread overview]
Message-ID: <20190620084620.17974-1-tao3.xu@intel.com> (raw)
UMONITOR, UMWAIT and TPAUSE are a set of user wait instructions.
UMONITOR arms address monitoring hardware using an address. A store
to an address within the specified address range triggers the
monitoring hardware to wake up the processor waiting in umwait.
UMWAIT instructs the processor to enter an implementation-dependent
optimized state while monitoring a range of addresses. The optimized
state may be either a light-weight power/performance optimized state
(c0.1 state) or an improved power/performance optimized state
(c0.2 state).
TPAUSE instructs the processor to enter an implementation-dependent
optimized state c0.1 or c0.2 state and wake up when time-stamp counter
reaches specified timeout.
Availability of the user wait instructions is indicated by the presence
of the CPUID feature flag WAITPKG CPUID.0x07.0x0:ECX[5].
The patches enable the umonitor, umwait and tpause features in KVM.
Because umwait and tpause can put a (psysical) CPU into a power saving
state, by default we dont't expose it to kvm and enable it only when
guest CPUID has it. If the instruction causes a delay, the amount
of time delayed is called here the physical delay. The physical delay is
first computed by determining the virtual delay (the time to delay
relative to the VM’s timestamp counter).
The release document ref below link:
Intel 64 and IA-32 Architectures Software Developer's Manual,
https://software.intel.com/sites/default/files/\
managed/39/c5/325462-sdm-vol-1-2abcd-3abcd.pdf
This patch has a dependency on https://lkml.org/lkml/2019/6/19/972
Changelog:
v5:
remove vmx_waitpkg_supported() to fix guest can rdmsr or wrmsr
when the feature is off (Xiaoyao)
rebase the patch because the kernel dependcy patch updated to
v5: https://lkml.org/lkml/2019/6/19/972
v4:
Set msr of IA32_UMWAIT_CONTROL can be 0 and add the check of
reserved bit 1 (Radim and Xiaoyao)
Use umwait_control_cached directly and add the IA32_UMWAIT_CONTROL
in msrs_to_save[] to support migration (Xiaoyao)
v3:
Simplify the patches, expose user wait instructions when the
guest has CPUID (Paolo)
Use mwait_control_cached to avoid frequently rdmsr of
IA32_UMWAIT_CONTROL (Paolo and Xiaoyao)
Handle vm-exit for UMWAIT and TPAUSE as "never happen" (Paolo)
v2:
Separated from the series https://lkml.org/lkml/2018/7/10/160
Add provide a capability to enable UMONITOR, UMWAIT and TPAUSE
v1:
Sent out with MOVDIRI/MOVDIR64B instructions patches
Tao Xu (3):
KVM: x86: add support for user wait instructions
KVM: vmx: Emulate MSR IA32_UMWAIT_CONTROL
KVM: vmx: handle vm-exit for UMWAIT and TPAUSE
arch/x86/include/asm/vmx.h | 1 +
arch/x86/include/uapi/asm/vmx.h | 6 ++++-
arch/x86/kernel/cpu/umwait.c | 3 ++-
arch/x86/kvm/cpuid.c | 2 +-
arch/x86/kvm/vmx/vmx.c | 44 +++++++++++++++++++++++++++++++++
arch/x86/kvm/vmx/vmx.h | 3 +++
arch/x86/kvm/x86.c | 1 +
7 files changed, 57 insertions(+), 3 deletions(-)
--
2.20.1
next reply other threads:[~2019-06-20 8:48 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-20 8:46 Tao Xu [this message]
2019-06-20 8:46 ` [PATCH v5 1/3] KVM: x86: add support for user wait instructions Tao Xu
2019-06-20 13:13 ` Xiaoyao Li
2019-06-20 8:46 ` [PATCH v5 2/3] KVM: vmx: Emulate MSR IA32_UMWAIT_CONTROL Tao Xu
2019-06-20 9:46 ` Xiaoyao Li
2019-07-02 16:37 ` Paolo Bonzini
2019-07-03 0:29 ` Tao Xu
2019-06-20 10:34 ` Xiaoyao Li
2019-06-20 8:46 ` [PATCH v5 3/3] KVM: vmx: handle vm-exit for UMWAIT and TPAUSE Tao Xu
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20190620084620.17974-1-tao3.xu@intel.com \
--to=tao3.xu@intel.com \
--cc=bp@alien8.de \
--cc=corbet@lwn.net \
--cc=fenghua.yu@intel.com \
--cc=hpa@zytor.com \
--cc=jingqi.liu@intel.com \
--cc=kvm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=pbonzini@redhat.com \
--cc=rkrcmar@redhat.com \
--cc=sean.j.christopherson@intel.com \
--cc=tglx@linutronix.de \
--cc=xiaoyao.li@linux.intel.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).