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79a197ab18
Previous to this change, a vCPU exposed with VMX running on a kernel without KVM_CAP_NESTED_STATE or KVM_CAP_EXCEPTION_PAYLOAD resulted in adding a migration blocker. This was because when the code was written it was thought there is no way to reliably know if a vCPU is utilising VMX or not at runtime. However, it turns out that this can be known to some extent: In order for a vCPU to enter VMX operation it must have CR4.VMXE set. Since it was set, CR4.VMXE must remain set as long as the vCPU is in VMX operation. This is because CR4.VMXE is one of the bits set in MSR_IA32_VMX_CR4_FIXED1. There is one exception to the above statement when vCPU enters SMM mode. When a vCPU enters SMM mode, it temporarily exits VMX operation and may also reset CR4.VMXE during execution in SMM mode. When the vCPU exits SMM mode, vCPU state is restored to be in VMX operation and CR4.VMXE is restored to its original state of being set. Therefore, when the vCPU is not in SMM mode, we can infer whether VMX is being used by examining CR4.VMXE. Otherwise, we cannot know for certain but assume the worse that vCPU may utilise VMX. Summaring all the above, a vCPU may have enabled VMX in case CR4.VMXE is set or vCPU is in SMM mode. Therefore, remove migration blocker and check before migration (cpu_pre_save()) if the vCPU may have enabled VMX. If true, only then require relevant kernel capabilities. While at it, demand KVM_CAP_EXCEPTION_PAYLOAD only when the vCPU is in guest-mode and there is a pending/injected exception. Otherwise, this kernel capability is not required for proper migration. Reviewed-by: Joao Martins <joao.m.martins@oracle.com> Signed-off-by: Liran Alon <liran.alon@oracle.com> Reviewed-by: Maran Wilson <maran.wilson@oracle.com> Tested-by: Maran Wilson <maran.wilson@oracle.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> |
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| .. | ||
| hvf | ||
| arch_dump.c | ||
| arch_memory_mapping.c | ||
| bpt_helper.c | ||
| cc_helper_template.h | ||
| cc_helper.c | ||
| cpu-param.h | ||
| cpu-qom.h | ||
| cpu.c | ||
| cpu.h | ||
| excp_helper.c | ||
| fpu_helper.c | ||
| gdbstub.c | ||
| hax-all.c | ||
| hax-i386.h | ||
| hax-interface.h | ||
| hax-mem.c | ||
| hax-posix.c | ||
| hax-posix.h | ||
| hax-windows.c | ||
| hax-windows.h | ||
| helper.c | ||
| helper.h | ||
| hyperv-proto.h | ||
| hyperv-stub.c | ||
| hyperv.c | ||
| hyperv.h | ||
| int_helper.c | ||
| kvm_i386.h | ||
| kvm-stub.c | ||
| kvm.c | ||
| machine.c | ||
| Makefile.objs | ||
| mem_helper.c | ||
| misc_helper.c | ||
| monitor.c | ||
| mpx_helper.c | ||
| ops_sse_header.h | ||
| ops_sse.h | ||
| seg_helper.c | ||
| sev_i386.h | ||
| sev-stub.c | ||
| sev.c | ||
| shift_helper_template.h | ||
| smm_helper.c | ||
| svm_helper.c | ||
| svm.h | ||
| TODO | ||
| trace-events | ||
| translate.c | ||
| whp-dispatch.h | ||
| whpx-all.c | ||
| xsave_helper.c | ||