On 19.03.2026 14:29, Ross Lagerwall wrote:
--- a/xen/arch/x86/cpu/common.c
+++ b/xen/arch/x86/cpu/common.c
@@ -883,9 +883,6 @@ void cpu_init(void)
/* Install correct page table. */
write_ptbase(current);
- /* Ensure FPU gets initialised for each domain. */
- stts();
I'm a little concerned by the removal of this and ...
@@ -193,31 +190,18 @@ void vcpu_restore_fpu(struct vcpu *v)
* On each context switch, save the necessary FPU info of VCPU being switch
* out. It dispatches saving operation based on CPU's capability.
*/
-static bool _vcpu_save_fpu(struct vcpu *v)
+void vcpu_save_fpu(struct vcpu *v)
{
ASSERT(!is_idle_vcpu(v));
/* This can happen, if a paravirtualised guest OS has set its CR0.TS. */
- clts();
+ if ( is_pv_vcpu(v) )
+ clts();
if ( cpu_has_xsave )
fpu_xsave(v);
else
fpu_fxsave(v);
-
- return true;
-}
-
-void vcpu_save_fpu(struct vcpu *v)
-{
- _vcpu_save_fpu(v);
- stts();
... this. At present it guards us against e.g. an idle CPU or context
switch code mistakenly using in particular XMM registers (but of course
also other extended state).
