On Thu, Jul 23, 2020 at 03:50:52PM +0530, Ravi Bangoria wrote:
> Power10 is introducing second DAWR. Use real register names (with
> suffix 0) from ISA for current macros and variables used by kvm.
Most of this looks fine, but I think we should not change the existing
names in arch/powerpc/include/uapi/asm/kvm.h (and therefore also
Documentation/virt/kvm/api.rst).
> diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
> index 426f94582b7a..4dc18fe6a2bf 100644
> --- a/Documentation/virt/kvm/api.rst
> +++ b/Documentation/virt/kvm/api.rst
> @@ -2219,8 +2219,8 @@ registers, find a list below:
> PPC KVM_REG_PPC_BESCR 64
> PPC KVM_REG_PPC_TAR 64
> PPC KVM_REG_PPC_DPDES 64
> - PPC KVM_REG_PPC_DAWR 64
> - PPC KVM_REG_PPC_DAWRX 64
> + PPC KVM_REG_PPC_DAWR0 64
> + PPC KVM_REG_PPC_DAWRX0 64
> PPC KVM_REG_PPC_CIABR 64
> PPC KVM_REG_PPC_IC 64
> PPC KVM_REG_PPC_VTB 64
...
> diff --git a/arch/powerpc/include/uapi/asm/kvm.h b/arch/powerpc/include/uapi/asm/kvm.h
> index 264e266a85bf..38d61b73f5ed 100644
> --- a/arch/powerpc/include/uapi/asm/kvm.h
> +++ b/arch/powerpc/include/uapi/asm/kvm.h
> @@ -608,8 +608,8 @@ struct kvm_ppc_cpu_char {
> #define KVM_REG_PPC_BESCR (KVM_REG_PPC | KVM_REG_SIZE_U64 | 0xa7)
> #define KVM_REG_PPC_TAR (KVM_REG_PPC | KVM_REG_SIZE_U64 | 0xa8)
> #define KVM_REG_PPC_DPDES (KVM_REG_PPC | KVM_REG_SIZE_U64 | 0xa9)
> -#define KVM_REG_PPC_DAWR (KVM_REG_PPC | KVM_REG_SIZE_U64 | 0xaa)
> -#define KVM_REG_PPC_DAWRX (KVM_REG_PPC | KVM_REG_SIZE_U64 | 0xab)
> +#define KVM_REG_PPC_DAWR0 (KVM_REG_PPC | KVM_REG_SIZE_U64 | 0xaa)
> +#define KVM_REG_PPC_DAWRX0 (KVM_REG_PPC | KVM_REG_SIZE_U64 | 0xab)
> #define KVM_REG_PPC_CIABR (KVM_REG_PPC | KVM_REG_SIZE_U64 | 0xac)
> #define KVM_REG_PPC_IC (KVM_REG_PPC | KVM_REG_SIZE_U64 | 0xad)
> #define KVM_REG_PPC_VTB (KVM_REG_PPC | KVM_REG_SIZE_U64 | 0xae)
The existing names are an API, and if you change them you will break
compilation of existing userspace programs. I don't see that adding
the '0' on the end is so important that we need to break userspace.
Paul.
