On 2/7/22 23:45, Leonardo Bras Soares Passos wrote:
On Mon, Feb 7, 2022 at 6:00 PM Paolo Bonzini <pbonzini@xxxxxxxxxx> wrote:
On 2/7/22 21:24, Leonardo Bras Soares Passos wrote:
With this patch,
we have to reason about the effect of calling KVM_SET_CPUID2 twice calls
back to back. I think an "&=" would be wrong in that case.
So, you suggest something like this ?
vcpu->arch.guest_fpu.fpstate->xfeatures =
fpu_user_cfg.default_features & vcpu->arch.guest_supported_xcr0;
Yes, but you need to change user_xfeatures instead of xfeatures.
KVM_GET_XSAVE and KVM_SET_XSAVE will take it into account automatically:
- KVM_GET_XSAVE: fpu_copy_guest_fpstate_to_uabi -> __copy_xstate_to_uabi_buf
- KVM_SET_XSAVE: fpu_copy_uabi_to_guest_fpstate ->
copy_uabi_from_kernel_to_xstate -> copy_uabi_to_xstate ->
validate_user_xstate_buffer
Ok, I understand how this replaces patch 2/2, so no issue on that.
About patch 1/2, you suggest that instead of fixing what we save in
the regs buffer, we fix only what we want to return to the user when
they call KVM_GET_XSAVE, is that correct?
Yes, exactly.
Paolo
