On 2/21/2023 8:36 AM, Mingwei Zhang wrote:
Avoid getting xstate address of init_fpstate if fpstate contains the xstate component. Since XTILEDATA (bit 18) was turned off in xinit, when KVM calls __raw_xsave_addr(xinit, 18), it triggers a warning as follows.
__raw_xsave_addr() is an internal function that assume caller does the checking, ie., all function arguments should be checked before calling. So, instead of removing the WARNING, add checks in __copy_xstate_to_uabi_buf().
<snip>
@@ -1151,10 +1152,11 @@ void __copy_xstate_to_uabi_buf(struct membuf to, struct fpstate *fpstate, pkru.pkru = pkru_val; membuf_write(&to, &pkru, sizeof(pkru)); } else {
copy_feature(header.xfeatures & BIT_ULL(i), &to,__raw_xsave_addr(xsave, i),__raw_xsave_addr(xinit, i),xstate_sizes[i]);
xsave_addr = (header.xfeatures & BIT_ULL(i)) ?__raw_xsave_addr(xsave, i) :__raw_xsave_addr(xinit, i);membuf_write(&to, xsave_addr, xstate_sizes[i]);
- Keep track of the last copied state in the non-compacted
So this hunk is under for_each_extended_xfeature(i, mask) -- it skips the copy routine if mask[i] == 0; instead, it fills zeros.
We have this [1]:
if (fpu_state_size_dynamic()) mask &= (header.xfeatures | xinit->header.xcomp_bv);
If header.xfeatures[18] = 0 then mask[18] = 0 because xinit->header.xcomp_bv[18] = 0. Then, it won't hit that code. So, I'm confused about the problem that you described here.
Can you elaborate on your test case a bit? Let me try to reproduce the issue on my end.
Thanks, Chang
[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch...