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KVM: MIPS: Change the definition of kvm type

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[ Upstream commit 15e9e35cd1 ]

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.

Signed-off-by: Huacai Chen <chenhc@lemote.com>
Message-Id: <1599734031-28746-1-git-send-email-chenhc@lemote.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Huacai Chen 2020-09-10 18:33:51 +08:00 committed by Greg Kroah-Hartman
parent a8c374444f
commit 09d69bfda6
2 changed files with 5 additions and 2 deletions
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2
arch/mips/kvm/mips.c
View File

@ -131,6 +131,8 @@ void kvm_arch_check_processor_compat(void *rtn)
int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
{
switch (type) {
case KVM_VM_MIPS_AUTO:
break;
#ifdef CONFIG_KVM_MIPS_VZ
case KVM_VM_MIPS_VZ:
#else

5
include/uapi/linux/kvm.h
View File

@ -735,9 +735,10 @@ struct kvm_ppc_resize_hpt {
#define KVM_VM_PPC_HV 1
#define KVM_VM_PPC_PR 2
/* on MIPS, 0 forces trap & emulate, 1 forces VZ ASE */
#define KVM_VM_MIPS_TE 0
/* on MIPS, 0 indicates auto, 1 forces VZ ASE, 2 forces trap & emulate */
#define KVM_VM_MIPS_AUTO 0
#define KVM_VM_MIPS_VZ 1
#define KVM_VM_MIPS_TE 2
#define KVM_S390_SIE_PAGE_OFFSET 1