Hi all, while digging into the PAT topic for Jailhouse, I also wondered how KVM deals with it. And I'm still not getting it complete - or there is a bug:
KVM intercepts all guest writes to the PAT MSR and instead keeps the guest value in vcpu->arch.pat. But, besides returning that value back on read accesses, arch.pat has no other purpose. On Intel, we only seem to have proper emulation - through hardware - when VMX supports PAT switching (see vmx_set_msr). On AMD, the situation is even worse as the g_pat save field is not updated at all on PAT writes. That seems to be a low hanging fruit to bring svm on the same support level as vmx. Or am I missing something? Jan PS: If someone has a good idea for a simple test case on machines without IOMMU (like my current boxes), thus without a chance to use device pass-through to stress guest PAT settings, I would be all ears. -- Siemens AG, Corporate Technology, CT RTC ITP SES-DE Corporate Competence Center Embedded Linux -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
