commit f701c082e72d4786686dfd1d9d877b64dc1d2804
author Vitaly Kuznetsov <vkuznets@redhat.com> Fri May 15 13:48:47 2020 +0200
committer Eduardo Habkost <ehabkost@redhat.com> Fri Sep 18 13:49:54 2020 -0400
tree 46c8fbd06b4942b1b10236bdaa764aac40da72e2
parent 053a4177817db307ec854356e95b5b350800a216

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>

docs/hyperv.txt

diff --git a/docs/hyperv.txt b/docs/hyperv.txt
index 6518b71..5df00da 100644
--- a/docs/hyperv.txt
+++ b/docs/hyperv.txt
@@ -49,7 +49,7 @@
 ======================
 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
 ================

target/i386/cpu.c

diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index 49d8958..37725bd 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -7263,7 +7263,7 @@
     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,

target/i386/cpu.h

diff --git a/target/i386/cpu.h b/target/i386/cpu.h
index d3097be..f519d2b 100644
--- a/target/i386/cpu.h
+++ b/target/i386/cpu.h
@@ -991,8 +991,8 @@
 #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

target/i386/kvm.c

diff --git a/target/i386/kvm.c b/target/i386/kvm.c
index d87af57..9efb07e 100644
--- a/target/i386/kvm.c
+++ b/target/i386/kvm.c
@@ -730,7 +730,7 @@
 {
     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 @@
             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;
             }
         }