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author | Zide Chen <zide.chen@intel.com> | 2024-06-03 17:02:22 -0700 |
---|---|---|
committer | Michael Tokarev <mjt@tls.msk.ru> | 2024-06-30 19:51:44 +0300 |
commit | 05fc711c3aa08ad800bf76eb0b7aeeb7a5cd0ecf (patch) | |
tree | ca717c0684e446b801f75387825982726330a889 /target/i386/kvm | |
parent | 3fd73736c69b71035cf1154ef58e8fa494f8612c (diff) | |
download | qemu-05fc711c3aa08ad800bf76eb0b7aeeb7a5cd0ecf.zip qemu-05fc711c3aa08ad800bf76eb0b7aeeb7a5cd0ecf.tar.gz qemu-05fc711c3aa08ad800bf76eb0b7aeeb7a5cd0ecf.tar.bz2 |
target/i386: Advertise MWAIT iff host supports
host_cpu_realizefn() sets CPUID_EXT_MONITOR without consulting host/KVM
capabilities. This may cause problems:
- If MWAIT/MONITOR is not available on the host, advertising this
feature to the guest and executing MWAIT/MONITOR from the guest
triggers #UD and the guest doesn't boot. This is because typically
#UD takes priority over VM-Exit interception checks and KVM doesn't
emulate MONITOR/MWAIT on #UD.
- If KVM doesn't support KVM_X86_DISABLE_EXITS_MWAIT, MWAIT/MONITOR
from the guest are intercepted by KVM, which is not what cpu-pm=on
intends to do.
In these cases, MWAIT/MONITOR should not be exposed to the guest.
The logic in kvm_arch_get_supported_cpuid() to handle CPUID_EXT_MONITOR
is correct and sufficient, and we can't set CPUID_EXT_MONITOR after
x86_cpu_filter_features().
This was not an issue before commit 662175b91ff ("i386: reorder call to
cpu_exec_realizefn") because the feature added in the accel-specific
realizefn could be checked against host availability and filtered out.
Additionally, it seems not a good idea to handle guest CPUID leaves in
host_cpu_realizefn(), and this patch merges host_cpu_enable_cpu_pm()
into kvm_cpu_realizefn().
Fixes: f5cc5a5c1686 ("i386: split cpu accelerators from cpu.c, using AccelCPUClass")
Fixes: 662175b91ff2 ("i386: reorder call to cpu_exec_realizefn")
Signed-off-by: Zide Chen <zide.chen@intel.com>
Reviewed-by: Zhao Liu <zhao1.liu@intel.com>
Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Michael Tokarev <mjt@tls.msk.ru>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
Diffstat (limited to 'target/i386/kvm')
-rw-r--r-- | target/i386/kvm/kvm-cpu.c | 11 |
1 files changed, 9 insertions, 2 deletions
diff --git a/target/i386/kvm/kvm-cpu.c b/target/i386/kvm/kvm-cpu.c index f9b99b5..d57a68a 100644 --- a/target/i386/kvm/kvm-cpu.c +++ b/target/i386/kvm/kvm-cpu.c @@ -64,8 +64,15 @@ static bool kvm_cpu_realizefn(CPUState *cs, Error **errp) * cpu_common_realizefn() (via xcc->parent_realize) */ if (cpu->max_features) { - if (enable_cpu_pm && kvm_has_waitpkg()) { - env->features[FEAT_7_0_ECX] |= CPUID_7_0_ECX_WAITPKG; + if (enable_cpu_pm) { + if (kvm_has_waitpkg()) { + env->features[FEAT_7_0_ECX] |= CPUID_7_0_ECX_WAITPKG; + } + + if (env->features[FEAT_1_ECX] & CPUID_EXT_MONITOR) { + host_cpuid(5, 0, &cpu->mwait.eax, &cpu->mwait.ebx, + &cpu->mwait.ecx, &cpu->mwait.edx); + } } if (cpu->ucode_rev == 0) { cpu->ucode_rev = |