On 7/16/2020 11:14 PM, Eduardo Habkost wrote:
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.
Sorry, I forgot x86_cpu_filter_features() totally when code inspection.
---
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
