Re: [PATCH] KVM: PPC: powerpc: Add count cache flush parameters to kvmppc_get_cpu_char()

Michael Ellerman
2019-03-01T06:52:51Z

Suraj Jitindar Singh <sjitindarsingh@gmail.com> writes:

> Add KVM_PPC_CPU_CHAR_BCCTR_FLUSH_ASSIST &
> KVM_PPC_CPU_BEHAV_FLUSH_COUNT_CACHE to the characteristics returned from
> the H_GET_CPU_CHARACTERISTICS H-CALL, as queried from either the
> hypervisor or the device tree.
>
> Signed-off-by: Suraj Jitindar Singh <sjitindarsingh@gmail.com>
> ---
> arch/powerpc/include/uapi/asm/kvm.h | 2 ++
> arch/powerpc/kvm/powerpc.c | 18 ++++++++++++++----
> 2 files changed, 16 insertions(+), 4 deletions(-)
>
> diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
> index b90a7d154180..a99dcac91e50 100644
> --- a/arch/powerpc/kvm/powerpc.c
> +++ b/arch/powerpc/kvm/powerpc.c
> @@ -2251,12 +2253,16 @@ static int kvmppc_get_cpu_char(struct kvm_ppc_cpu_char *cp)
> if (have_fw_feat(fw_features, "enabled",
> "fw-count-cache-disabled"))
> cp->character |= KVM_PPC_CPU_CHAR_COUNT_CACHE_DIS;
> + if (have_fw_feat(fw_features, "enabled",
> + "fw-count-cache-flush-bcctr2,0,0"))

I don't think there's any reason KVM needs to be querying the device
tree directly, is there?

Can't it just use the security flags (security_features.h), that are
initialised by the powernv platform code based on the device tree.

I seem to remember we didn't do it that way originally just because we
didn't have time to get everything lined up.

cheers