On 26/06/20 20:18, Sean Christopherson wrote: >> Btw, would it be more staightforward to check "vcpu->arch.arch_capabilities & >> ARCH_CAP_TSX_CTRL_MSR" rather than "*ebx | (F(RTM) | F(HLE))" even if we want >> to have such a fix? > Not really, That ends up duplicating the check in vmx_get_msr(). From an > emulation perspective, this really is a "guest" access to the MSR, in the > sense that it the virtual CPU is in the guest domain, i.e. not a god-like > entity that gets to break the rules of emulation. But if you wrote a guest that wants to read MSR_IA32_TSX_CTRL, there are two choices: 1) check ARCH_CAPABILITIES first 2) blindly access it and default to 0. Both are fine, because we know MSR_IA32_TSX_CTRL has no reserved/must-be-one bits. Calling __kvm_get_msr and checking for an invalid MSR through the return value is not breaking the rules of emulation, it is "faking" a #GP handler. So I think Peter's patch is fine, but (possibly on top as a third patch) __must_check should be added to MSR getters and setters. Also one possibility is to return -EINVAL for invalid MSRs. Paolo
