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KVM: MIPS: Change the definition of kvm type

MIPS defines two kvm types: #define KVM_VM_MIPS_TE 0 #define KVM_VM_MIPS_VZ 1 In Documentation/virt/kvm/api.rst it is said that "You probably want to use 0 as machine type", which implies that type 0 be the "automatic" or "default" type. And, in user-space libvirt use the null-machine (with type 0) to detect the kvm capability, which returns "KVM not supported" on a VZ platform. I try to fix it in QEMU but it is ugly: https://lists.nongnu.org/archive/html/qemu-devel/2020-08/msg05629.html And Thomas Huth suggests me to change the definition of kvm type: https://lists.nongnu.org/archive/html/qemu-devel/2020-09/msg03281.html So I define like this: #define KVM_VM_MIPS_AUTO 0 #define KVM_VM_MIPS_VZ 1 #define KVM_VM_MIPS_TE 2 Since VZ and TE cannot co-exists, using type 0 on a TE platform will still return success (so old user-space tools have no problems on new kernels); the advantage is that using type 0 on a VZ platform will not return failure. So, the only problem is "new user-space tools use type 2 on old kernels", but if we treat this as a kernel bug, we can backport this patch to old stable kernels.

Huacai Chen committed 6 years ago

Commit 15e9e351 parent f6f61952 files · +5 −2Browse files

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include/uapi/linux/kvm.h+3−2
@@ -790,9 +790,10 @@ struct kvm_ppc_resize_hpt { · 789 unmodified lines
790790 #define KVM_VM_PPC_HV 1
791791 #define KVM_VM_PPC_PR 2
792792
793−/* on MIPS, 0 forces trap & emulate, 1 forces VZ ASE */
794−#define KVM_VM_MIPS_TE 0
793+/* on MIPS, 0 indicates auto, 1 forces VZ ASE, 2 forces trap & emulate */
794+#define KVM_VM_MIPS_AUTO 0
795795 #define KVM_VM_MIPS_VZ 1
796+#define KVM_VM_MIPS_TE 2
796797
797798 #define KVM_S390_SIE_PAGE_OFFSET 1
798799