From mboxrd@z Thu Jan 1 00:00:00 1970 From: Laurent Vivier Subject: Re: [kvm-unit-tests PATCH v3] powerpc: Check whether TM is available before running other tests Date: Tue, 4 Oct 2016 11:45:40 +0200 Message-ID: References: <1475572050-13164-1-git-send-email-thuth@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Cc: =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= , kvm-ppc@vger.kernel.org, Drew Jones , Suraj Jitindar Singh To: Thomas Huth , kvm@vger.kernel.org Return-path: Received: from mx1.redhat.com ([209.132.183.28]:60906 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750724AbcJDJpo (ORCPT ); Tue, 4 Oct 2016 05:45:44 -0400 In-Reply-To: <1475572050-13164-1-git-send-email-thuth@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On 04/10/2016 11:07, Thomas Huth wrote: > Transactional memory is currently only supported on KVM-HV, and > not yet on KVM-PR. So it's better to check the device tree first > and fail gracefully if it is not available. > > Reviewed-by: Laurent Vivier > Reviewed-by: Andrew Jones > Signed-off-by: Thomas Huth > --- > v3: > - Removed unnecessary check for "plen >= 26" in cpu_has_tm() > > v2: > - Reworked the check for the "ibm,pa-features" and added a comment > - Use a dedicated variable "has_tm" instead of "i" in main() > > powerpc/tm.c | 43 ++++++++++++++++++++++++++++++++++++++++++- > 1 file changed, 42 insertions(+), 1 deletion(-) > > diff --git a/powerpc/tm.c b/powerpc/tm.c > index 6ce750a..b611061 100644 > --- a/powerpc/tm.c > +++ b/powerpc/tm.c > @@ -10,6 +10,41 @@ > #include > #include > #include > +#include > +#include > + > +/* Check "ibm,pa-features" property of a CPU node for the TM flag */ > +static void cpu_has_tm(int fdtnode, u32 regval __unused, void *ptr) > +{ > + const struct fdt_property *prop; > + int plen; > + > + prop = fdt_get_property(dt_fdt(), fdtnode, "ibm,pa-features", &plen); > + if (!prop) /* No features means TM is also not available */ > + return; > + /* Sanity check for the property layout (first two bytes are header) */ > + assert(plen >= 8 && prop->data[1] == 0 && prop->data[0] <= plen - 2); > + > + /* > + * The "Transactional Memory Category Support" flags are at byte > + * offset 22 and 23 of the attribute type 0, so when adding the > + * two bytes for the header, we've got to look at offset 24 for > + * the TM support bit. > + */ > + if (prop->data[0] >= 24 && (prop->data[24] & 0x80) != 0) > + *(int *)ptr += 1; > +} in the future, if we think we can have more than the type 0, we should scan the property with something like: off = 0 while (off + 1 < plen) { if (prop->data[off + 1] != 0) { off += 2 + prop->data[off]; continue; } ... check TM ... } but I don't think we need that now... Laurent