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@xxxxxxxxx> --- arch/x86/kernel/fpu/xstate.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c index 4753c677e2e1..c5d903b4df4d 100644 --- a/arch/x86/kernel/fpu/xstate.c +++ b/arch/x86/kernel/fpu/xstate.c @@ -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 */ -- 2.27.0
