On Fri, Dec 10, 2021 at 05:02:49PM +0100, Paolo Bonzini wrote: > First, the MSR should be added to msrs_to_save_all and > kvm_cpu_cap_has(X86_FEATURE_XFD) should be checked in > kvm_init_msr_list. > > It seems that RDMSR support is missing, too. > > More important, please include: > > - documentation for the new KVM_EXIT_* value > > - a selftest that explains how userspace should react to it. > > This is a strong requirement for any new API (the first has been for > years; but the latter is also almost always respected these days). > This series should not have been submitted without documentation. > > Also: > > On 12/8/21 01:03, Yang Zhong wrote: > > > >+ if (!guest_cpuid_has(vcpu, X86_FEATURE_XFD)) > >+ return 1; > > This should allow msr->host_initiated always (even if XFD is not > part of CPUID). However, if XFD is nonzero and > kvm_check_guest_realloc_fpstate returns true, then it should return > 1. > > The selftest should also cover using KVM_GET_MSR/KVM_SET_MSR. > Paolo, Seems we do not need new KVM_EXIT_* again from below thomas' new patchset: git://git.kernel.org/pub/scm/linux/kernel/git/people/tglx/devel.git x86/fpu-kvm So the selftest stll need support KVM_GET_MSR/KVM_SET_MSR for MSR_IA32_XFD and MSR_IA32_XFD_ERR? If yes, we only do some read/write test with vcpu_set_msr()/ vcpu_get_msr() from new selftest tool? or do wrmsr from guest side and check this value from selftest side? I checked some msr selftest reference code, tsc_msrs_test.c, which maybe better for this reference. If you have better suggestion, please share it to me. thanks! Yang
