Hi, This series aims to complete KVM support of VMware backdoor interface. This interface is currently partially supported. Before these commits, KVM forwaded accesses to vmport I/O ports to QEMU where they were handled correctly. However, it turns out VMware design allows these I/O ports to also be accessible to guest when TSS I/O permissions bitmap disallows it. The way VMware hypervisor does it is to intercept #GP and on #GP intercept handler run the x86 emulator which was modified to specifically skip checking TSS I/O permissions bitmap for these magic I/O ports. This behavior was found to be a must for some VMware workloads. For example, VMware Tools Windows installer refuse to install as it cannot access vmport I/O ports from Ring3, therefore assuming it is not running inside a VM. Patches 1-6 mimics the above behavior in KVM. It installs a #GP intercept on both VMX & SVM such that the #GP intercept handler will call x86 emulator which was modified to always allow access to these I/O ports. Because this behavior is not a must for all workloads and #GP intercept can introduce a slight performance overhead, a module parameter was added to control whether KVM will do this or not. Patch 7 finally completes VMware backdoor interface by adding support for VMware Pseduo-PMCs. VMware defines a couple of PMCs which are made-up by their hypervisor which returns various PV information (Such as host's RDTSC). Similar to vmport I/O ports, these Pseduo-PMCs can be accessed via RDPMC even if executed from Ring3 when CR4.PCE=0. Therefore, the x86 emulator was modified to mimic this behavior. Regards, -Liran Alon
