On Wed, Dec 29, 2021, Yang Zhong wrote:
+static void handle_nm_fault_irqoff(struct kvm_vcpu *vcpu) +{
- rdmsrl(MSR_IA32_XFD_ERR, vcpu->arch.guest_fpu.xfd_err);
- kvm_queue_exception(vcpu, NM_VECTOR);
This is still wrong, even though no additional supported is needed to support nested XFD. If L1 wants to intercept #NM, then KVM must not inject the #NM and must not read XFD_ERR.
That this was posted multiple times is disturbing, because kvm-unit-tests has a test for exactly this, and running it against this series on a host without XFD yields:
unchecked MSR access error: RDMSR from 0x1c5 at rIP: 0xffffffffa02478ee (vmx_handle_exit_irqoff+0x1de/0x240 [kvm_intel]) Call Trace: <TASK> kvm_arch_vcpu_ioctl_run+0x11a0/0x1fb0 [kvm] kvm_vcpu_ioctl+0x279/0x690 [kvm] __x64_sys_ioctl+0x83/0xb0 do_syscall_64+0x3b/0xc0 entry_SYSCALL_64_after_hwframe+0x44/0xae </TASK>