Paul Mackerras <paulus@xxxxxxxxxx> writes: > On Fri, Mar 01, 2019 at 05:52:51PM +1100, Michael Ellerman wrote: >> Suraj Jitindar Singh <sjitindarsingh@xxxxxxxxx> 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@xxxxxxxxx> >> > --- >> > 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. > > My recollection is that the security flags didn't have all the > information we need. It's possible that's no longer true. Actually I don't think they existed at all back then, we didn't add them until after the initial panic. > I merged the patch and sent a pull request to Paolo; using the same > pattern as the existing code made it a low-risk patch and I wanted to > get it in for 5.1. For 5.2 we can look at changing it over if you > like. Yep that's fine. cheers
