Re: [PATCH] KVM: MIPS: Change the definition of kvm type

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Thu, Sep 10, 2020 at 12:34 PM Huacai Chen <chenhc@xxxxxxxxxx> wrote:
>
> 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

I'm not sure this is helpful information to keep in the commit message.

Otherwise:
Reviewed-by: Philippe Mathieu-Daudé <f4bug@xxxxxxxxx>

>
> And Thomas Huth suggests me to change the definition of kvm type:
> https://lists.nongnu.org/archive/html/qemu-devel/2020-09/msg03281.html

Suggested-by: Thomas Huth <thuth@xxxxxxxxxx>

>
> 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.
>
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Huacai Chen <chenhc@xxxxxxxxxx>
> ---
>  arch/mips/kvm/mips.c     | 2 ++
>  include/uapi/linux/kvm.h | 5 +++--
>  2 files changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/arch/mips/kvm/mips.c b/arch/mips/kvm/mips.c
> index d7ba3f9..9efeb67 100644
> --- a/arch/mips/kvm/mips.c
> +++ b/arch/mips/kvm/mips.c
> @@ -138,6 +138,8 @@ extern void kvm_init_loongson_ipi(struct kvm *kvm);
>  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
> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
> index 29ba8e8..cfc1ae2 100644
> --- a/include/uapi/linux/kvm.h
> +++ b/include/uapi/linux/kvm.h
> @@ -790,9 +790,10 @@ 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
>
> --
> 2.7.0
>



[Index of Archives]     [KVM ARM]     [KVM ia64]     [KVM ppc]     [Virtualization Tools]     [Spice Development]     [Libvirt]     [Libvirt Users]     [Linux USB Devel]     [Linux Audio Users]     [Yosemite Questions]     [Linux Kernel]     [Linux SCSI]     [XFree86]

  Powered by Linux