linux-kernel - [PATCH RFC 6/7] Doc/KVM: introduce a new cpuid bit for kvm pvtimer

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Date:   Fri,  8 Dec 2017 16:39:49 +0800
From:   Quan Xu <quan.xu0@...il.com>
To:     pbonzini@...hat.com, rkrcmar@...hat.com
Cc:     yang.zhang.wz@...il.com, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, Ben Luo <bn0418@...il.com>,
        Quan Xu <quan.xu0@...il.com>
Subject: [PATCH RFC 6/7] Doc/KVM: introduce a new cpuid bit for kvm pvtimer

From: Ben Luo <bn0418@...il.com>

KVM_FEATURE_PV_TIMER enables guest to check whether pvtimer
can be enabled in guest.

Signed-off-by: Yang Zhang <yang.zhang.wz@...il.com>
Signed-off-by: Quan Xu <quan.xu0@...il.com>
Signed-off-by: Ben Luo <bn0418@...il.com>
---
 Documentation/virtual/kvm/cpuid.txt  |    4 ++++
 arch/x86/include/uapi/asm/kvm_para.h |    1 +
 arch/x86/kvm/cpuid.c                 |    1 +
 3 files changed, 6 insertions(+), 0 deletions(-)

diff --git a/Documentation/virtual/kvm/cpuid.txt b/Documentation/virtual/kvm/cpuid.txt
index 3c65feb..b26b31c 100644
--- a/Documentation/virtual/kvm/cpuid.txt
+++ b/Documentation/virtual/kvm/cpuid.txt
@@ -54,6 +54,10 @@ KVM_FEATURE_PV_UNHALT              ||     7 || guest checks this feature bit
                                    ||       || before enabling paravirtualized
                                    ||       || spinlock support.
 ------------------------------------------------------------------------------
+KVM_FEATURE_PV_TIMER               ||     8 || guest checks this feature bit
+                                   ||       || before enabling paravirtualized
+                                   ||       || timer support.
+------------------------------------------------------------------------------
 KVM_FEATURE_CLOCKSOURCE_STABLE_BIT ||    24 || host will warn if no guest-side
                                    ||       || per-cpu warps are expected in
                                    ||       || kvmclock.
diff --git a/arch/x86/include/uapi/asm/kvm_para.h b/arch/x86/include/uapi/asm/kvm_para.h
index 3dd6116..46734a8 100644
--- a/arch/x86/include/uapi/asm/kvm_para.h
+++ b/arch/x86/include/uapi/asm/kvm_para.h
@@ -25,6 +25,7 @@
 #define KVM_FEATURE_STEAL_TIME		5
 #define KVM_FEATURE_PV_EOI		6
 #define KVM_FEATURE_PV_UNHALT		7
+#define KVM_FEATURE_PV_TIMER		8
 
 /* The last 8 bits are used to indicate how to interpret the flags field
  * in pvclock structure. If no bits are set, all flags are ignored.
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 0099e10..e02fd23 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -593,6 +593,7 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
 			     (1 << KVM_FEATURE_CLOCKSOURCE2) |
 			     (1 << KVM_FEATURE_ASYNC_PF) |
 			     (1 << KVM_FEATURE_PV_EOI) |
+			     (1 << KVM_FEATURE_PV_TIMER) |
 			     (1 << KVM_FEATURE_CLOCKSOURCE_STABLE_BIT) |
 			     (1 << KVM_FEATURE_PV_UNHALT);
 
-- 
1.7.1