On 10/29/2025 12:58 PM, Chao Gao wrote:
On Fri, Oct 24, 2025 at 02:56:23PM +0800, Zhao Liu wrote:
From: Yang Weijiang <[email protected]>
Add CET_U/S bits in xstate area and report support in xstate
feature mask.
MSR_XSS[bit 11] corresponds to CET user mode states.
MSR_XSS[bit 12] corresponds to CET supervisor mode states.
CET Shadow Stack(SHSTK) and Indirect Branch Tracking(IBT) features
are enumerated via CPUID.(EAX=07H,ECX=0H):ECX[7] and EDX[20]
respectively, two features share the same state bits in XSS, so
if either of the features is enabled, set CET_U and CET_S bits
together.
Tested-by: Farrah Chen <[email protected]>
Signed-off-by: Yang Weijiang <[email protected]>
Co-developed-by: Chao Gao <[email protected]>
Signed-off-by: Chao Gao <[email protected]>
Co-developed-by: Zhao Liu <[email protected]>
Signed-off-by: Zhao Liu <[email protected]>
It just occurred to me that KVM_GET/SET_XSAVE don't save/restore supervisor
states. Supervisor states need to be saved/restored via MSR APIs. So, there
is no need to add supervisor states (including ARCH_LBR states) to
x86_ext_save_areas[].
x86_ext_save_areas[] is not used only for xsave state, it's also used
for the setup of xsave features, i.e., CPUID leaf 0xD.
And you did catch the missing part of this series, it lacks the
save/restore of CET XSAVE state in
x86_cpu_xsave_all_areas()/x86_cpu_xrstor_all_areas()
