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KVM: x86: believe what KVM says about WAITPKG

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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: qemu-stable@nongnu.org
Reported-by: Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Paolo Bonzini 2020-06-30 09:49:27 -04:00
parent c0c8445255
commit e1e43813e7
3 changed files with 9 additions and 6 deletions
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3
target/i386/cpu.c
View File

@ -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,

11
target/i386/kvm.c
View File

@ -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;
}

1
target/i386/kvm_i386.h
View File

@ -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);