@@ -1636,9 +1636,17 @@ static int __xstate_request_perm(u64 permitted, u64 requested, bool guest)
/* Calculate the resulting kernel state size */
mask = permitted | requested;
- /* Take supervisor states into account on the host */
+ /*
+ * Take supervisor states into account on the host. And add
+ * kernel dynamic xfeatures to guest since guest kernel may
+ * enable corresponding CPU feaures and the xstate registers
+ * need to be saved/restored properly.
+ */
if (!guest)
mask |= xfeatures_mask_supervisor();
+ else
+ mask |= fpu_kernel_dynamic_xfeatures;
+
ksize = xstate_calculate_size(mask, compacted);
/* Calculate the resulting user state size */
When user space requests guest xstate permits, the sufficient xstate size is calculated from permitted mask. Currently the max guest permits are set to fpu_kernel_cfg.default_features, and the latter doesn't include kernel dynamic xfeatures, so add them back for correct guest fpstate size. If guest dynamic xfeatures are enabled, KVM re-allocates guest fpstate area with above resulting size before launches VM. Signed-off-by: Yang Weijiang <weijiang.yang@intel.com> --- arch/x86/kernel/fpu/xstate.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-)