i386/kvm: correct the meaning of '0xffffffff' value for hv-spinlocks

Hyper-V TLFS prior to version 6.0 had a mistake in it: special value
'0xffffffff' for CPUID 0x40000004.EBX was called 'never to retry', this
looked weird (like why it's not '0' which supposedly have the same effect?)
but nobody raised the question. In TLFS version 6.0 the mistake was
corrected to 'never notify' which sounds logical. Fix QEMU accordingly.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20200515114847.74523-1-vkuznets@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>

diff --git a/docs/hyperv.txt b/docs/hyperv.txt
index 6518b716a9585c995a7beb21c87384b33eb71390..5df00da54fc48fffc56a882b2133ad0043598a4f 100644 (file)
--- a/docs/hyperv.txt
+++ b/docs/hyperv.txt
@@ -49,7 +49,7 @@ more efficiently. In particular, this enlightenment allows paravirtualized
 ======================
 Enables paravirtualized spinlocks. The parameter indicates how many times
 spinlock acquisition should be attempted before indicating the situation to the
-hypervisor. A special value 0xffffffff indicates "never to retry".
+hypervisor. A special value 0xffffffff indicates "never notify".
 
 3.4. hv-vpindex
 ================

diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index 49d89585288d3b55ec2b66f0de922ec76a0b5f1e..37725bd354d05d75ee24c9c50668d2abe456c540 100644 (file)
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -7263,7 +7263,7 @@ static Property x86_cpu_properties[] = {
     DEFINE_PROP_BOOL("pmu", X86CPU, enable_pmu, false),
 
     DEFINE_PROP_UINT32("hv-spinlocks", X86CPU, hyperv_spinlock_attempts,
-                       HYPERV_SPINLOCK_NEVER_RETRY),
+                       HYPERV_SPINLOCK_NEVER_NOTIFY),
     DEFINE_PROP_BIT64("hv-relaxed", X86CPU, hyperv_features,
                       HYPERV_FEAT_RELAXED, 0),
     DEFINE_PROP_BIT64("hv-vapic", X86CPU, hyperv_features,

diff --git a/target/i386/cpu.h b/target/i386/cpu.h
index d3097be6a50a1f4e21777bf5603fe7ca09de47ef..f519d2bfd48d097baafb4bb2796fce6a534f4aa4 100644 (file)
--- a/target/i386/cpu.h
+++ b/target/i386/cpu.h
@@ -991,8 +991,8 @@ typedef uint64_t FeatureWordArray[FEATURE_WORDS];
 #define HYPERV_FEAT_IPI                 13
 #define HYPERV_FEAT_STIMER_DIRECT       14
 
-#ifndef HYPERV_SPINLOCK_NEVER_RETRY
-#define HYPERV_SPINLOCK_NEVER_RETRY             0xFFFFFFFF
+#ifndef HYPERV_SPINLOCK_NEVER_NOTIFY
+#define HYPERV_SPINLOCK_NEVER_NOTIFY             0xFFFFFFFF
 #endif
 
 #define EXCP00_DIVZ    0

diff --git a/target/i386/kvm.c b/target/i386/kvm.c
index d87af57a23ce6245e70595a018c0bcd33843cdb5..9efb07e7c8390dd9b699b3b45d4085aa57fbc7be 100644 (file)
--- a/target/i386/kvm.c
+++ b/target/i386/kvm.c
@@ -730,7 +730,7 @@ static bool hyperv_enabled(X86CPU *cpu)
 {
     CPUState *cs = CPU(cpu);
     return kvm_check_extension(cs->kvm_state, KVM_CAP_HYPERV) > 0 &&
-        ((cpu->hyperv_spinlock_attempts != HYPERV_SPINLOCK_NEVER_RETRY) ||
+        ((cpu->hyperv_spinlock_attempts != HYPERV_SPINLOCK_NEVER_NOTIFY) ||
          cpu->hyperv_features || cpu->hyperv_passthrough);
 }
 
@@ -1236,7 +1236,7 @@ static int hyperv_handle_properties(CPUState *cs,
             env->features[FEAT_HV_RECOMM_EAX] = c->eax;
 
             /* hv-spinlocks may have been overriden */
-            if (cpu->hyperv_spinlock_attempts != HYPERV_SPINLOCK_NEVER_RETRY) {
+            if (cpu->hyperv_spinlock_attempts != HYPERV_SPINLOCK_NEVER_NOTIFY) {
                 c->ebx = cpu->hyperv_spinlock_attempts;
             }
         }