On 1/8/2021 2:40 AM, Bae, Chang Seok wrote:
On Jan 7, 2021, at 17:41, Liu, Jing2 <jing2.liu@xxxxxxxxx> wrote:
static void kvm_save_current_fpu(struct fpu *fpu) {
+ struct fpu *src_fpu = ¤t->thread.fpu;
+
/*
* If the target FPU state is not resident in the CPU registers, just
* memcpy() from current, else save CPU state directly to the target.
*/
- if (test_thread_flag(TIF_NEED_FPU_LOAD))
- memcpy(&fpu->state, ¤t->thread.fpu.state,
+ if (test_thread_flag(TIF_NEED_FPU_LOAD)) {
+ memcpy(&fpu->state, &src_fpu->state,
fpu_kernel_xstate_min_size);
For kvm, if we assume that it does not support dynamic features until this series,
memcpy for only fpu->state is correct.
I think this kind of assumption is reasonable and we only make original xstate work.
- else
+ } else {
+ if (fpu->state_mask != src_fpu->state_mask)
+ fpu->state_mask = src_fpu->state_mask;
Though dynamic feature is not supported in kvm now, this function still need
consider more things for fpu->state_mask.
Can you elaborate this? Which path might be affected by fpu->state_mask
without dynamic state supported in KVM?
I suggest that we can set it before if...else (for both cases) and not change other.
I tried a minimum change here. The fpu->state_mask value does not impact the
memcpy(). So, why do we need to change it for both?
Sure, what I'm considering is that "mask" is the first time introduced
into "fpu",
representing the usage, so not only set it when needed, but also make it
as a
representation, in case of anywhere using it (especially between the
interval
of this series and kvm series in future).
Thanks,
Jing
Thanks,
Chang
