linux-kernel - [tip:locking/core] Documentation/virtual/kvm: Support the vCPU preemption check

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Date:   Tue, 22 Nov 2016 04:35:45 -0800
From:   tip-bot for Pan Xinhui <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     rkrcmar@...hat.com, xinhui.pan@...ux.vnet.ibm.com,
        torvalds@...ux-foundation.org, mingo@...nel.org,
        tglx@...utronix.de, peterz@...radead.org, hpa@...or.com,
        linux-kernel@...r.kernel.org, pbonzini@...hat.com
Subject: [tip:locking/core] Documentation/virtual/kvm: Support the vCPU
 preemption check

Commit-ID:  3dd3e0ce7989b645eee0174b17f5095e187c7f28
Gitweb:     http://git.kernel.org/tip/3dd3e0ce7989b645eee0174b17f5095e187c7f28
Author:     Pan Xinhui <xinhui.pan@...ux.vnet.ibm.com>
AuthorDate: Wed, 2 Nov 2016 05:08:38 -0400
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Tue, 22 Nov 2016 12:48:09 +0100

Documentation/virtual/kvm: Support the vCPU preemption check

Commit ("x86/kvm: support vCPU preemption check") added a new
struct kvm_steal_time::preempted field. This field tells us if
a vCPU is running or not.

It is zero if some old KVM does not support this field or if the vCPU
is not preempted. Other values means the vCPU has been preempted.

Signed-off-by: Pan Xinhui <xinhui.pan@...ux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Acked-by: Radim Krčmář <rkrcmar@...hat.com>
Acked-by: Paolo Bonzini <pbonzini@...hat.com>
Cc: David.Laight@...LAB.COM
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: benh@...nel.crashing.org
Cc: boqun.feng@...il.com
Cc: borntraeger@...ibm.com
Cc: bsingharora@...il.com
Cc: dave@...olabs.net
Cc: jgross@...e.com
Cc: kernellwp@...il.com
Cc: konrad.wilk@...cle.com
Cc: linuxppc-dev@...ts.ozlabs.org
Cc: mpe@...erman.id.au
Cc: paulmck@...ux.vnet.ibm.com
Cc: paulus@...ba.org
Cc: virtualization@...ts.linux-foundation.org
Cc: will.deacon@....com
Cc: xen-devel-request@...ts.xenproject.org
Cc: xen-devel@...ts.xenproject.org
Link: http://lkml.kernel.org/r/1478077718-37424-12-git-send-email-xinhui.pan@linux.vnet.ibm.com
[ Various typo fixes. ]
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 Documentation/virtual/kvm/msr.txt | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/Documentation/virtual/kvm/msr.txt b/Documentation/virtual/kvm/msr.txt
index 2a71c8f..0a9ea51 100644
--- a/Documentation/virtual/kvm/msr.txt
+++ b/Documentation/virtual/kvm/msr.txt
@@ -208,7 +208,9 @@ MSR_KVM_STEAL_TIME: 0x4b564d03
 		__u64 steal;
 		__u32 version;
 		__u32 flags;
-		__u32 pad[12];
+		__u8  preempted;
+		__u8  u8_pad[3];
+		__u32 pad[11];
 	}
 
 	whose data will be filled in by the hypervisor periodically. Only one
@@ -232,6 +234,11 @@ MSR_KVM_STEAL_TIME: 0x4b564d03
 		nanoseconds. Time during which the vcpu is idle, will not be
 		reported as steal time.
 
+		preempted: indicate the vCPU who owns this struct is running or
+		not. Non-zero values mean the vCPU has been preempted. Zero
+		means the vCPU is not preempted. NOTE, it is always zero if the
+		the hypervisor doesn't support this field.
+
 MSR_KVM_EOI_EN: 0x4b564d04
 	data: Bit 0 is 1 when PV end of interrupt is enabled on the vcpu; 0
 	when disabled.  Bit 1 is reserved and must be zero.  When PV end of