isaku.yamahata@xxxxxxxxx writes:
> From: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
>
> Move processor compatibility check from kvm_arch_processor_compat() into
^
kvm_arch_check_processor_compat()
> kvm_arch_hardware_setup(). The check does model name comparison with a
> global variable, cur_cpu_spec. There is no point to check it at run time
> on all processors.
A key detail I had to look up is that both kvm_arch_hardware_setup() and
kvm_arch_check_processor_compat() are called from kvm_init(), one after
the other. But the latter is called on each CPU.
And because the powerpc implementation of kvm_arch_check_processor_compat()
just checks a global, there's no need to call it on every CPU.
> kvmppc_core_check_processor_compat() checks the global variable. There are
> five implementation for it as follows.
There are three implementations not five.
> arch/powerpc/include/asm/cputable.h: extern struct cpu_spec *cur_cpu_spec;
> arch/powerpc/kvm/book3s.c: return 0
> arch/powerpc/kvm/e500.c: strcmp(cur_cpu_spec->cpu_name, "e500v2")
> arch/powerpc/kvm/e500mc.c: strcmp(cur_cpu_spec->cpu_name, "e500mc")
> strcmp(cur_cpu_spec->cpu_name, "e5500")
> strcmp(cur_cpu_spec->cpu_name, "e6500")
>
> Suggested-by: Sean Christopherson <seanjc@xxxxxxxxxx>
> Signed-off-by: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
> Cc: linuxppc-dev@xxxxxxxxxxxxxxxx
> Cc: Fabiano Rosas <farosas@xxxxxxxxxxxxx>
> ---
> arch/powerpc/kvm/powerpc.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
> index 7b56d6ccfdfb..31dc4f231e9d 100644
> --- a/arch/powerpc/kvm/powerpc.c
> +++ b/arch/powerpc/kvm/powerpc.c
> @@ -444,12 +444,12 @@ int kvm_arch_hardware_enable(void)
>
> int kvm_arch_hardware_setup(void *opaque)
> {
> - return 0;
> + return kvmppc_core_check_processor_compat();
> }
>
> int kvm_arch_check_processor_compat(void)
> {
> - return kvmppc_core_check_processor_compat();
> + return 0;
> }
The actual change seems OK. I gave it a quick test boot and ran some
VMs, everything seems to work as before.
Acked-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx> (powerpc)
cheers
