Re: [PATCH v5 27/30] RFC: KVM: powerpc: Move processor compatibility check to hardware setup
On Fri, Sep 23, 2022 at 04:58:41PM +1000,
Michael Ellerman wrote:
> isaku.yamah...@intel.com writes:
> > From: Isaku Yamahata
> >
> > 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.
Thanks. I'll update the commit message.
> > 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
> > Signed-off-by: Isaku Yamahata
> > Cc: linuxppc-dev@lists.ozlabs.org
> > Cc: Fabiano Rosas
> > ---
> > 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 (powerpc)
Thanks so much for testing. I'll remove RFC.
--
Isaku Yamahata
Re: [PATCH v5 27/30] RFC: KVM: powerpc: Move processor compatibility check to hardware setup
isaku.yamah...@intel.com writes:
> From: Isaku Yamahata
>
> 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
> Signed-off-by: Isaku Yamahata
> Cc: linuxppc-dev@lists.ozlabs.org
> Cc: Fabiano Rosas
> ---
> 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 (powerpc)
cheers
[PATCH v5 27/30] RFC: KVM: powerpc: Move processor compatibility check to hardware setup
From: Isaku Yamahata
Move processor compatibility check from kvm_arch_processor_compat() into
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.
kvmppc_core_check_processor_compat() checks the global variable. There are
five implementation for it as follows.
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
Signed-off-by: Isaku Yamahata
Cc: linuxppc-dev@lists.ozlabs.org
Cc: Fabiano Rosas
---
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;
}
int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
--
2.25.1
