From: Jing Liu jing2.liu@intel.com
When XFD causes an instruction to generate #NM, IA32_XFD_ERR contains information about which disabled state components are being accessed. The #NM handler is expected to check this information and then enable the state components by clearing IA32_XFD for the faulting task (if having permission).
If the XFD_ERR value generated in guest is consumed/clobbered by the host before the guest itself doing so. This may lead to non-XFD-related #NM treated as XFD #NM in host (due to non-zero value in XFD_ERR), or XFD-related #NM treated as non-XFD #NM in guest (XFD_ERR cleared by the host #NM handler).
Introduce a new field in fpu_guest to save the guest xfd_err value. KVM is expected to save guest xfd_err before preemption is enabled and restore it right before entering the guest (with preemption disabled).
Signed-off-by: Kevin Tian kevin.tian@intel.com Signed-off-by: Jing Liu jing2.liu@intel.com Signed-off-by: Yang Zhong yang.zhong@intel.com --- arch/x86/include/asm/fpu/types.h | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/arch/x86/include/asm/fpu/types.h b/arch/x86/include/asm/fpu/types.h index c752d0aa23a4..3795d0573773 100644 --- a/arch/x86/include/asm/fpu/types.h +++ b/arch/x86/include/asm/fpu/types.h @@ -517,6 +517,11 @@ struct fpu_guest { */ u64 perm;
+ /* + * @xfd_err: Save the guest value. + */ + u64 xfd_err; + /* * @fpstate: Pointer to the allocated guest fpstate */