From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marcelo Tosatti Subject: [patch 01/18] KVM: x86: retain pvclock guest stopped bit in guest memory Date: Wed, 24 Oct 2012 11:13:41 -0200 Message-ID: <20121024131621.332503444@redhat.com> References: <20121024131340.742340256@redhat.com> Cc: johnstul@us.ibm.com, jeremy@goop.org, glommer@parallels.com, zamsden@gmail.com, gleb@redhat.com, avi@redhat.com, pbonzini@redhat.com, Marcelo Tosatti To: kvm@vger.kernel.org Return-path: Received: from mx1.redhat.com ([209.132.183.28]:38303 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932343Ab2JXNV4 (ORCPT ); Wed, 24 Oct 2012 09:21:56 -0400 Content-Disposition: inline; filename=x86-kvm-retain-guest-stopped.patch Sender: kvm-owner@vger.kernel.org List-ID: Otherwise its possible for an unrelated KVM_REQ_UPDATE_CLOCK (such as due to CPU migration) to clear the bit. Noticed by Paolo Bonzini. Signed-off-by: Marcelo Tosatti Index: vsyscall/arch/x86/kvm/x86.c =================================================================== --- vsyscall.orig/arch/x86/kvm/x86.c +++ vsyscall/arch/x86/kvm/x86.c @@ -1143,6 +1143,7 @@ static int kvm_guest_time_update(struct unsigned long this_tsc_khz; s64 kernel_ns, max_kernel_ns; u64 tsc_timestamp; + struct pvclock_vcpu_time_info *guest_hv_clock; u8 pvclock_flags; /* Keep irq disabled to prevent changes to the clock */ @@ -1226,13 +1227,6 @@ static int kvm_guest_time_update(struct vcpu->last_kernel_ns = kernel_ns; vcpu->last_guest_tsc = tsc_timestamp; - pvclock_flags = 0; - if (vcpu->pvclock_set_guest_stopped_request) { - pvclock_flags |= PVCLOCK_GUEST_STOPPED; - vcpu->pvclock_set_guest_stopped_request = false; - } - - vcpu->hv_clock.flags = pvclock_flags; /* * The interface expects us to write an even number signaling that the @@ -1243,6 +1237,18 @@ static int kvm_guest_time_update(struct shared_kaddr = kmap_atomic(vcpu->time_page); + guest_hv_clock = shared_kaddr + vcpu->time_offset; + + /* retain PVCLOCK_GUEST_STOPPED if set in guest copy */ + pvclock_flags = (guest_hv_clock->flags & PVCLOCK_GUEST_STOPPED); + + if (vcpu->pvclock_set_guest_stopped_request) { + pvclock_flags |= PVCLOCK_GUEST_STOPPED; + vcpu->pvclock_set_guest_stopped_request = false; + } + + vcpu->hv_clock.flags = pvclock_flags; + memcpy(shared_kaddr + vcpu->time_offset, &vcpu->hv_clock, sizeof(vcpu->hv_clock));