From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michael Ellerman Subject: Re: [PATCH] KVM: PPC: powerpc: Add count cache flush parameters to kvmppc_get_cpu_char() Date: Sun, 03 Mar 2019 20:06:29 +1100 Message-ID: <87wolgiay2.fsf@concordia.ellerman.id.au> References: <20190301032516.29919-1-sjitindarsingh@gmail.com> <87bm2vjdbw.fsf@concordia.ellerman.id.au> <20190301080113.GB22341@blackberry> Mime-Version: 1.0 Content-Type: text/plain Cc: linuxppc-dev@lists.ozlabs.org, kvm-ppc@vger.kernel.org, Suraj Jitindar Singh , kvm@vger.kernel.org To: Paul Mackerras Return-path: In-Reply-To: <20190301080113.GB22341@blackberry> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linuxppc-dev-bounces+glppe-linuxppc-embedded-2=m.gmane.org@lists.ozlabs.org Sender: "Linuxppc-dev" List-Id: kvm.vger.kernel.org Paul Mackerras writes: > On Fri, Mar 01, 2019 at 05:52:51PM +1100, Michael Ellerman wrote: >> Suraj Jitindar Singh 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 >> > --- >> > 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