kvm: rename KVM_HINTS_DEDICATED to KVM_HINTS_REALTIME

KVM_HINTS_DEDICATED seems to be somewhat confusing:

Guest doesn't really care whether it's the only task running on a host
CPU as long as it's not preempted.

And there are more reasons for Guest to be preempted than host CPU
sharing, for example, with memory overcommit it can get preempted on a
memory access, post copy migration can cause preemption, etc.

Let's call it KVM_HINTS_REALTIME which seems to better
match what guests expect.

Also, the flag most be set on all vCPUs - current guests assume this.
Note so in the documentation.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/Documentation/virtual/kvm/cpuid.txt b/Documentation/virtual/kvm/cpuid.txt
index d4f33eb805dd228a8d8aff796bd77327334aa24b..ab022dcd09117571d215294ed51c5675543165f1 100644 (file)
--- a/Documentation/virtual/kvm/cpuid.txt
+++ b/Documentation/virtual/kvm/cpuid.txt
@@ -72,8 +72,8 @@ KVM_FEATURE_CLOCKSOURCE_STABLE_BIT ||    24 || host will warn if no guest-side
 
 flag                               || value || meaning
 ==================================================================================
-KVM_HINTS_DEDICATED                ||     0 || guest checks this feature bit to
-                                   ||       || determine if there is vCPU pinning
-                                   ||       || and there is no vCPU over-commitment,
+KVM_HINTS_REALTIME                 ||     0 || guest checks this feature bit to
+                                   ||       || determine that vCPUs are never
+                                   ||       || preempted for an unlimited time,
                                    ||       || allowing optimizations
 ----------------------------------------------------------------------------------

diff --git a/arch/x86/include/uapi/asm/kvm_para.h b/arch/x86/include/uapi/asm/kvm_para.h
index 4c851ebb3cebd4654f9dabed1e9c19520b072c0d..0ede697c396119be61eb223a40607ff6e6e985ef 100644 (file)
--- a/arch/x86/include/uapi/asm/kvm_para.h
+++ b/arch/x86/include/uapi/asm/kvm_para.h
@@ -29,7 +29,7 @@
 #define KVM_FEATURE_PV_TLB_FLUSH       9
 #define KVM_FEATURE_ASYNC_PF_VMEXIT    10
 
-#define KVM_HINTS_DEDICATED      0
+#define KVM_HINTS_REALTIME      0
 
 /* 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/kernel/kvm.c b/arch/x86/kernel/kvm.c
index 7867417cfaff2b59ee2c2531072a632a9e810f41..5b2300b818af9333f8d57f6b082f426b8556b606 100644 (file)
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -457,7 +457,7 @@ static void __init sev_map_percpu_data(void)
 static void __init kvm_smp_prepare_cpus(unsigned int max_cpus)
 {
        native_smp_prepare_cpus(max_cpus);
-       if (kvm_para_has_hint(KVM_HINTS_DEDICATED))
+       if (kvm_para_has_hint(KVM_HINTS_REALTIME))
                static_branch_disable(&virt_spin_lock_key);
 }
 
@@ -553,7 +553,7 @@ static void __init kvm_guest_init(void)
        }
 
        if (kvm_para_has_feature(KVM_FEATURE_PV_TLB_FLUSH) &&
-           !kvm_para_has_hint(KVM_HINTS_DEDICATED) &&
+           !kvm_para_has_hint(KVM_HINTS_REALTIME) &&
            kvm_para_has_feature(KVM_FEATURE_STEAL_TIME))
                pv_mmu_ops.flush_tlb_others = kvm_flush_tlb_others;
 
@@ -649,7 +649,7 @@ static __init int kvm_setup_pv_tlb_flush(void)
        int cpu;
 
        if (kvm_para_has_feature(KVM_FEATURE_PV_TLB_FLUSH) &&
-           !kvm_para_has_hint(KVM_HINTS_DEDICATED) &&
+           !kvm_para_has_hint(KVM_HINTS_REALTIME) &&
            kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) {
                for_each_possible_cpu(cpu) {
                        zalloc_cpumask_var_node(per_cpu_ptr(&__pv_tlb_mask, cpu),
@@ -745,7 +745,7 @@ void __init kvm_spinlock_init(void)
        if (!kvm_para_has_feature(KVM_FEATURE_PV_UNHALT))
                return;
 
-       if (kvm_para_has_hint(KVM_HINTS_DEDICATED))
+       if (kvm_para_has_hint(KVM_HINTS_REALTIME))
                return;
 
        __pv_init_lock_hash();