On 7/7/2020 12:41 AM, Paolo Bonzini wrote:
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-sta...@nongnu.org
Reported-by: Maxim Levitsky <mlevi...@redhat.com>
Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
---
target/i386/cpu.c | 3 +++
target/i386/kvm.c | 11 +++++------
target/i386/kvm_i386.h | 1 +
3 files changed, 9 insertions(+), 6 deletions(-)
diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index c44cc510e1..dc9ba06f1f 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -6536,6 +6536,9 @@ 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;
+ }
Hi Paolo and Maxim,
Sorry to find out this long-time-ago mail although the code has been
refactor nowadays. Recently, when testing WAITPKG exposure, I found
WAITPKG is no longer controlled by "-overcommit cpu-pm", i.e. if
!enable_cpu_pm && KVM cap reports WAITPKG (KVM set the cap in
vmx_set_cpu_caps), this feature can still be seen in guest. It is
obviously due to QEMU doesn't clear CPUID_7_0_ECX_WAITPKG explicitly if
!enable_cpu_pm.
So, is this the expected behavior for this patch?
Thanks
Chenyi
}
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..b8455c89ed 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.
@@ -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 00bde7acaf..064b8798a2 100644
--- 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);
--
2.26.2
