From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paolo Bonzini Subject: Re: [PATCH 1/3] target-i386: kvm: Abort if MCE bank count is not supported by host Date: Wed, 25 Nov 2015 17:46:38 +0100 Message-ID: <5655E5EE.8060906@redhat.com> References: <1448466589-9407-1-git-send-email-ehabkost@redhat.com> <1448466589-9407-2-git-send-email-ehabkost@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Cc: Marcelo Tosatti , kvm@vger.kernel.org, ying.huang@intel.com, Borislav Petkov , =?UTF-8?Q?Andreas_F=c3=a4rber?= , Richard Henderson To: Eduardo Habkost , qemu-devel@nongnu.org Return-path: Received: from mx1.redhat.com ([209.132.183.28]:55161 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752234AbbKYQqo (ORCPT ); Wed, 25 Nov 2015 11:46:44 -0500 In-Reply-To: <1448466589-9407-2-git-send-email-ehabkost@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On 25/11/2015 16:49, Eduardo Habkost wrote: > Instead of silently changing the number of banks in mcg_cap based > on kvm_get_mce_cap_supported(), abort initialization if the host > doesn't support MCE_BANKS_DEF banks. > > Note that MCE_BANKS_DEF was always 10 since it was introduced in > QEMU, and Linux always returned 32 at KVM_CAP_MCE since > KVM_CAP_MCE was introduced, so no behavior is being changed and > the error can't be triggered by any Linux version. The point of > the new check is to ensure we won't silently change the bank > count if we change MCE_BANKS_DEF or make the bank count > configurable in the future. > > Signed-off-by: Eduardo Habkost > --- > target-i386/kvm.c | 9 ++++++--- > 1 file changed, 6 insertions(+), 3 deletions(-) > > diff --git a/target-i386/kvm.c b/target-i386/kvm.c > index 2a9953b..ee7bc69 100644 > --- a/target-i386/kvm.c > +++ b/target-i386/kvm.c > @@ -784,11 +784,14 @@ int kvm_arch_init_vcpu(CPUState *cs) > return ret; > } > > - if (banks > MCE_BANKS_DEF) { > - banks = MCE_BANKS_DEF; > + if (MCE_BANKS_DEF > banks) { > + error_report("kvm: Unsupported MCE bank count: %d > %d\n", > + MCE_BANKS_DEF, banks); Yoda conditions? if (banks < MCE_BANKS_DEF) { error_report("kvm: Unsupported MCE bank count (QEMU = %d, KVM = %d)", MCE_BANKS_DEF, banks); Paolo > + return -ENOTSUP; > } > + > mcg_cap &= MCE_CAP_DEF; > - mcg_cap |= banks; > + mcg_cap |= MCE_BANKS_DEF; > ret = kvm_vcpu_ioctl(cs, KVM_X86_SETUP_MCE, &mcg_cap); > if (ret < 0) { > fprintf(stderr, "KVM_X86_SETUP_MCE: %s", strerror(-ret)); >