Messages in this thread |  | | Subject | Re: [PATCH 1/2] X86/KVM: Properly update 'tsc_offset' to represent the running guest | From | Paolo Bonzini <> | Date | Fri, 13 Apr 2018 17:35:12 +0200 |
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On 13/04/2018 14:40, Raslan, KarimAllah wrote: >> >> static void update_ia32_tsc_adjust_msr(struct kvm_vcpu *vcpu, s64 offset) >> { >> - u64 curr_offset = vcpu->arch.tsc_offset; >> + u64 curr_offset = kvm_x86_ops->read_l1_tsc_offset(vcpu); > I might be missing something but is this really strictly needed or is > it really a bug? > > I can see update_ia32_tsc_adjust_msr called from kvm_write_tsc only > which is called from a) vmx_set_msr or b) kvm_arch_vcpu_postcreate. > The adjust_msr would only be called if !host_initiated. So only > vmx_set_msr which is coming from an L1 write (or a restore but that > would not be !host_initiated). So the only that tsc_adjust is called is > !is_guest_mode.
It can also be called from guest mode if the MSR bitmap says there's no L1 vmexit for that MSR; that's what the testcases do.
Paolo
>> vcpu->arch.ia32_tsc_adjust_msr += offset - curr_offset;
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