[Qemu-devel] Re: [PATCH 0/9] S390x KVM support

[Avi Kivity <avi@redhat.com>]

On 10/20/2009 06:40 PM, Carsten Otte wrote:
>
> This patch moves s390 processor status word into the base kvm_run
> struct and keeps it up-to date on all userspace exits.
>
> +#include <linux/autoconf.h>
> #include <linux/types.h>
> #include <linux/compiler.h>
> #include <linux/ioctl.h>

Not needed.

> @@ -116,6 +117,11 @@
>     __u64 cr8;
>     __u64 apic_base;
>
> +#ifdef CONFIG_S390
> +    /* the processor status word for s390 */
> +    __u64 psw_mask; /* psw upper half */
> +    __u64 psw_addr; /* psw lower half */
> +#endif

Doesn't this break backward compatibility by changing the structure?

Best to put it after the union (and as a copy, so userspace that expects 
the previous location still works).  If you're reading it from the 
kernel, also need a way to tell the kernel which copy to read from.

Also advertise with a KVM_CAP.

Additionally, CONFIG_ in public headers are frowned upon as 
non-portable.  A workaround is to #define __KVM_S390 in <asm/kvm.h> and 
depend on that.

> --- kvm.orig/arch/s390/kvm/kvm-s390.c    2009-10-20 15:01:02.000000000 
> +0200
> +++ kvm/arch/s390/kvm/kvm-s390.c    2009-10-20 18:13:45.000000000 +0200
> @@ -421,7 +421,8 @@
>     if (atomic_read(&vcpu->arch.sie_block->cpuflags) & CPUSTAT_RUNNING)
>         rc = -EBUSY;
>     else
> -        vcpu->arch.sie_block->gpsw = psw;
> +        vcpu->run->psw_mask = psw.mask;
> +        vcpu->run->psw_addr = psw.addr;

It's traditional to add braces around multi-line else blocks.

I'd also appreciate an explanation of what this is all about.

-- 
error compiling committee.c: too many arguments to function