i386: hvf: Don't duplicate register reset
hvf_reset_vcpu() duplicates actions performed by x86_cpu_reset(). The difference is that hvf_reset_vcpu() stores initial values directly to VMCS while x86_cpu_reset() stores it in CPUX86State and then cpu_synchronize_all_post_init() or cpu_synchronize_all_post_reset() flushes CPUX86State into VMCS. That makes hvf_reset_vcpu() a kind of no-op. Here's the trace of CPU state modifications during VM start: hvf_reset_vcpu (resets VMCS) cpu_synchronize_all_post_init (overwrites VMCS fields written by hvf_reset_vcpu()) cpu_synchronize_all_states hvf_reset_vcpu (resets VMCS) cpu_synchronize_all_post_reset (overwrites VMCS fields written by hvf_reset_vcpu()) General purpose registers, system registers, segment descriptors, flags and IP are set by hvf_put_segments() in post-init and post-reset, therefore it's safe to remove them from hvf_reset_vcpu(). PDPTE initialization can be dropped because Intel SDM (26.3.1.6 Checks on Guest Page-Directory-Pointer-Table Entries) doesn't require PDPTE to be clear unless PAE is used: "A VM entry to a guest that does not use PAE paging does not check the validity of any PDPTEs." And if PAE is used, PDPTE's are initialized from CR3 in macvm_set_cr0(). Cc: Cameron Esfahani <dirty@apple.com> Signed-off-by: NRoman Bolshakov <r.bolshakov@yadro.com> Message-Id: <20200630102824.77604-8-r.bolshakov@yadro.com> Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
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