[PATCH v4 6/6] KVM: X86: Expose PV_SEND_IPI CPUID feature bit to guest

[Wanpeng Li]

From: Wanpeng Li <wanpengli@xxxxxxxxxxx>

Expose PV_SEND_IPI feature bit to guest, the guest can check this feature
bit before using paravirtualized send IPIs.

Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Cc: Radim KrÄmÃÅ <rkrcmar@xxxxxxxxxx>
Cc: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
Signed-off-by: Wanpeng Li <wanpengli@xxxxxxxxxxx>
---
 Documentation/virtual/kvm/cpuid.txt | 4 ++++
 arch/x86/kvm/cpuid.c                | 3 ++-
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/Documentation/virtual/kvm/cpuid.txt b/Documentation/virtual/kvm/cpuid.txt
index ab022dc..97ca194 100644
--- a/Documentation/virtual/kvm/cpuid.txt
+++ b/Documentation/virtual/kvm/cpuid.txt
@@ -62,6 +62,10 @@ KVM_FEATURE_ASYNC_PF_VMEXIT        ||    10 || paravirtualized async PF VM exit
                                    ||       || can be enabled by setting bit 2
                                    ||       || when writing to msr 0x4b564d02
 ------------------------------------------------------------------------------
+KVM_FEATURE_PV_SEND_IPI            ||    11 || guest checks this feature bit
+                                   ||       || before using paravirtualized
+                                   ||       || send IPIs.
+------------------------------------------------------------------------------
 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/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 7e042e3..7bcfa61 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -621,7 +621,8 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
 			     (1 << KVM_FEATURE_CLOCKSOURCE_STABLE_BIT) |
 			     (1 << KVM_FEATURE_PV_UNHALT) |
 			     (1 << KVM_FEATURE_PV_TLB_FLUSH) |
-			     (1 << KVM_FEATURE_ASYNC_PF_VMEXIT);
+			     (1 << KVM_FEATURE_ASYNC_PF_VMEXIT) |
+			     (1 << KVM_FEATURE_PV_SEND_IPI);
 
 		if (sched_info_on())
 			entry->eax |= (1 << KVM_FEATURE_STEAL_TIME);
-- 
2.7.4