From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:54381) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dedqj-0001Qk-L3 for qemu-devel@nongnu.org; Mon, 07 Aug 2017 04:57:22 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dedqe-0007Dh-N0 for qemu-devel@nongnu.org; Mon, 07 Aug 2017 04:57:21 -0400 Received: from mx1.redhat.com ([209.132.183.28]:57646) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1dedqe-0007Cp-GQ for qemu-devel@nongnu.org; Mon, 07 Aug 2017 04:57:16 -0400 From: Ladi Prosek Date: Mon, 7 Aug 2017 10:56:59 +0200 Message-Id: <20170807085703.32267-1-lprosek@redhat.com> Subject: [Qemu-devel] [PATCH v2 0/4] i386/kvm: advertise Hyper-V frequency MSRs List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org, kvm@vger.kernel.org Cc: pbonzini@redhat.com, mtosatti@redhat.com, david@redhat.com, rkrcmar@redhat.com This is the QEMU part of the changes required for nested Hyper-V to read timestamps with RDTSC + TSC page. Without exposing the frequency MSRs, Windows with the Hyper-V role enabled use the much slower HV_X64_MSR_TIME_REF_COUNT (0x40000020) RDMSR to read timestamps. The new registers are exposed only if the TSC frequency is stable across migration and known, as suggested by Paolo. v1->v2: * deleted an extra empty line in patch 1 * added patch 3 introducing a helper function for the "TSC is stable and known" check (David) Ladi Prosek (4): i386/kvm: use a switch statement for MSR detection i386/kvm: set tsc_khz before configuring Hyper-V CPUID i386/kvm: introduce tsc_is_stable_and_known() i386/kvm: advertise Hyper-V frequency MSRs target/i386/kvm.c | 138 ++++++++++++++++++++++++++++-------------------------- 1 file changed, 71 insertions(+), 67 deletions(-) -- 2.9.3