[PATCH] KVM: x86: believe what KVM says about WAITPKG

[Paolo Bonzini]

Currently, QEMU is overriding KVM_GET_SUPPORTED_CPUID's answer for
the WAITPKG bit depending on the "-overcommit cpu-pm" setting.  This is a
bad idea because it does not even check if the host supports it, but it
can be done in x86_cpu_realizefn just like we do for the MONITOR bit.

This patch moves it there, of course making it conditional on host
availability which is not being done for the MONITOR bit.  It also makes
MONITOR conditional, though not strictly necessary, so that the code
looks the same for both and generally more natural.

Cc: qemu-stable@nongnu.org
Reported-by: Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 target/i386/cpu.c | 5 ++++-
 target/i386/kvm.c | 6 ------
 2 files changed, 4 insertions(+), 7 deletions(-)

diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index c44cc510e1..0de8dc569a 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -6535,7 +6535,10 @@ static void x86_cpu_realizefn(DeviceState *dev, Error 
**errp)
         if (enable_cpu_pm) {
             host_cpuid(5, 0, &cpu->mwait.eax, &cpu->mwait.ebx,
                        &cpu->mwait.ecx, &cpu->mwait.edx);
-            env->features[FEAT_1_ECX] |= CPUID_EXT_MONITOR;
+            env->features[FEAT_1_ECX] |=
+                x86_cpu_get_supported_feature_word(FEAT_1_ECX, 
cpu->migratable) & CPUID_EXT_MONITOR;
+            env->features[FEAT_7_0_ECX] |=
+                x86_cpu_get_supported_feature_word(FEAT_7_0_ECX, 
cpu->migratable) & CPUID_7_0_ECX_WAITPKG;
         }
         if (kvm_enabled() && cpu->ucode_rev == 0) {
             cpu->ucode_rev = kvm_arch_get_supported_msr_feature(kvm_state,
diff --git a/target/i386/kvm.c b/target/i386/kvm.c
index 2b6b7443d2..c9ef27080d 100644
--- a/target/i386/kvm.c
+++ b/target/i386/kvm.c
@@ -411,12 +411,6 @@ uint32_t kvm_arch_get_supported_cpuid(KVMState *s, 
uint32_t function,
         if (host_tsx_blacklisted()) {
             ret &= ~(CPUID_7_0_EBX_RTM | CPUID_7_0_EBX_HLE);
         }
-    } else if (function == 7 && index == 0 && reg == R_ECX) {
-        if (enable_cpu_pm) {
-            ret |= CPUID_7_0_ECX_WAITPKG;
-        } else {
-            ret &= ~CPUID_7_0_ECX_WAITPKG;
-        }
     } else if (function == 7 && index == 0 && reg == R_EDX) {
         /*
          * Linux v4.17-v4.20 incorrectly return ARCH_CAPABILITIES on SVM hosts.
-- 
2.26.2