On Thu, Jul 16, 2020 at 04:20:19PM +0800, Xiaoyao Li wrote: > When setting up XSAVE components, it needs to mask off those unsupported > by KVM. > > Signed-off-by: Xiaoyao Li <xiaoyao...@intel.com>
We must never disable CPUID features silently based on host capabilities, otherwise we can't guarantee guest ABI stability when migrating to another host. Filtering of features should involve a call to mark_unavailable_features() (or some equivalent mechanism) so we can report the missing features properly through QMP. Could you explain what's the bug you are trying to fix? The loop at x86_cpu_filter_features() is already supposed to disable features unsupported by the host. > --- > target/i386/cpu.c | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/target/i386/cpu.c b/target/i386/cpu.c > index f5f11603e805..efc92334b7b1 100644 > --- a/target/i386/cpu.c > +++ b/target/i386/cpu.c > @@ -6274,8 +6274,10 @@ static void x86_cpu_enable_xsave_components(X86CPU > *cpu) > } > } > > - env->features[FEAT_XSAVE_COMP_LO] = mask; > - env->features[FEAT_XSAVE_COMP_HI] = mask >> 32; > + env->features[FEAT_XSAVE_COMP_LO] = mask & > + x86_cpu_get_supported_feature_word(FEAT_XSAVE_COMP_LO, > cpu->migratable); > + env->features[FEAT_XSAVE_COMP_HI] = (mask >> 32) & > + x86_cpu_get_supported_feature_word(FEAT_XSAVE_COMP_HI, > cpu->migratable); > } > > /***** Steps involved on loading and filtering CPUID data > -- > 2.18.4 > -- Eduardo
