On Tue, Jan 14, 2025, Adrian Hunter wrote: > On 10/01/25 19:30, Sean Christopherson wrote: > >> Currently the KVM selftests expect to be able to set XCR0: > >> > >> td_vcpu_add() > >> vm_vcpu_add() > >> vm_arch_vcpu_add() > >> vcpu_init_xcrs() > >> vcpu_xcrs_set() > >> vcpu_ioctl(KVM_SET_XCRS) > >> __TEST_ASSERT_VM_VCPU_IOCTL(!ret) > >> > >> Seems like vm->arch.has_protected_state is needed for KVM selftests? > > > > I doubt it's truly needed, my guess (without looking at the code) is that selftests > > are fudging around the fact that KVM doesn't stuff arch.xcr0. > > Here is when it was added: > > commit 8b14c4d85d031f7700fa4e042aebf99d933971f0 > Author: Sean Christopherson <seanjc@xxxxxxxxxx> > Date: Thu Oct 3 16:43:31 2024 -0700 > > KVM: selftests: Configure XCR0 to max supported value by default > > To play nice with compilers generating AVX instructions, set CR4.OSXSAVE > and configure XCR0 by default when creating selftests vCPUs. Some distros > have switched gcc to '-march=x86-64-v3' by default, and while it's hard to > find a CPU which doesn't support AVX today, many KVM selftests fail with Gah, sorry. I misread the callstack the first time around and didn't realize it was the common code that was writing XCR0. > Is below OK to avoid it? Skipping the ioctls to set XCRs and SREGS is definitely ok. I'll hold off on providing concrete feedback until I review the TDX selftests in its entirety, as I'm skeptical of having td_vcpu_add() wrap vm_arch_vcpu_add() instead of the other way around, but I don't want to cause a bunch of noise by reacting to a sliver of the code.
