KVM: x86: believe what KVM says about WAITPKG

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, while making it conditional on host
support for the related UMWAIT MSR.

Cc: [email protected]
Reported-by: Maxim Levitsky <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>

diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index 1546cd78ff4befc23e2ededb26746f625bea9efd..105eb47eab53adad83da874e43b74a4ed2cd816e 100644 (file)
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -6509,6 +6509,9 @@ static void x86_cpu_realizefn(DeviceState *dev, Error **errp)
             host_cpuid(5, 0, &cpu->mwait.eax, &cpu->mwait.ebx,
                        &cpu->mwait.ecx, &cpu->mwait.edx);
             env->features[FEAT_1_ECX] |= CPUID_EXT_MONITOR;
+            if (kvm_enabled() && kvm_has_waitpkg()) {
+                env->features[FEAT_7_0_ECX] |= 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 2b6b7443d2730f0e61f80389ce30cef854bab827..b8455c89ed09632ef09631ae51fae22a936e2028 100644 (file)
--- 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.
@@ -4730,3 +4724,8 @@ int kvm_arch_msi_data_to_gsi(uint32_t data)
 {
     abort();
 }
+
+bool kvm_has_waitpkg(void)
+{
+    return has_msr_umwait;
+}

diff --git a/target/i386/kvm_i386.h b/target/i386/kvm_i386.h
index 00bde7acaf21612cbb519e656350ab141f260482..064b8798a26c4ac4d34d619ef74cd5a4a19122dc 100644 (file)
--- a/target/i386/kvm_i386.h
+++ b/target/i386/kvm_i386.h
@@ -44,6 +44,7 @@ void kvm_put_apicbase(X86CPU *cpu, uint64_t value);
 
 bool kvm_enable_x2apic(void);
 bool kvm_has_x2apic_api(void);
+bool kvm_has_waitpkg(void);
 
 bool kvm_hv_vpindex_settable(void);