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From 9a68121178334ac95dd057c98a3b8922a243fb93 Mon Sep 17 00:00:00 2001
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Message-Id: <9a68121178334ac95dd057c98a3b8922a243fb93.1383922567.git.jdenemar@redhat.com>
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From: Peter Krempa <pkrempa@redhat.com>
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Date: Fri, 8 Nov 2013 12:33:35 +0100
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Subject: [PATCH] qemu: process: Validate specific CPUID flags of a guest
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https://bugzilla.redhat.com/show_bug.cgi?id=1008989
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When starting a VM the qemu process may filter out some requested
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features of a domain as it's not supported either by the host or by
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qemu. Libvirt didn't check if this happened which might end up in
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changing of the guest ABI when migrating.
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The proof of concept implementation adds the check for the recently
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introduced kvm_pv_unhalt cpuid feature bit. This feature depends on both
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qemu and host kernel support and thus increase the possibility of guest
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ABI breakage.
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(cherry picked from commit d94b7817719b064849818b9ba6c37e403b7c003c)
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Signed-off-by: Jiri Denemark <jdenemar@redhat.com>
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---
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src/qemu/qemu_process.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++
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1 file changed, 46 insertions(+)
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diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c
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index e0097df..40e3754 100644
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--- a/src/qemu/qemu_process.c
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+++ b/src/qemu/qemu_process.c
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@@ -43,6 +43,7 @@
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#include "qemu_bridge_filter.h"
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#include "qemu_migration.h"
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+#include "cpu/cpu.h"
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#include "datatypes.h"
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#include "virlog.h"
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#include "virerror.h"
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@@ -3437,6 +3438,47 @@ qemuValidateCpuMax(virDomainDefPtr def, virQEMUCapsPtr qemuCaps)
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return true;
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}
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+
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+static bool
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+qemuProcessVerifyGuestCPU(virQEMUDriverPtr driver, virDomainObjPtr vm)
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+{
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+ virDomainDefPtr def = vm->def;
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+ virArch arch = def->os.arch;
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+ virCPUDataPtr guestcpu = NULL;
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+ qemuDomainObjPrivatePtr priv = vm->privateData;
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+ bool ret = false;
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+
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+ switch (arch) {
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+ case VIR_ARCH_I686:
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+ case VIR_ARCH_X86_64:
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+ qemuDomainObjEnterMonitor(driver, vm);
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+ guestcpu = qemuMonitorGetGuestCPU(priv->mon, arch);
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+ qemuDomainObjExitMonitor(driver, vm);
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+
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+ if (!(guestcpu))
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+ goto cleanup;
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+
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+ if (def->features[VIR_DOMAIN_FEATURE_PVSPINLOCK] == VIR_DOMAIN_FEATURE_STATE_ON) {
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+ if (!cpuHasFeature(guestcpu, VIR_CPU_x86_KVM_PV_UNHALT)) {
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+ virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
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+ _("host doesn't support paravirtual spinlocks"));
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+ goto cleanup;
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+ }
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+ }
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+ break;
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+
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+ default:
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+ break;
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+ }
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+
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+ ret = true;
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+
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+cleanup:
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+ cpuDataFree(guestcpu);
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+ return ret;
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+}
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+
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+
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int qemuProcessStart(virConnectPtr conn,
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virQEMUDriverPtr driver,
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virDomainObjPtr vm,
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@@ -3904,6 +3946,10 @@ int qemuProcessStart(virConnectPtr conn,
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priv->agentError = true;
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}
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+ VIR_DEBUG("Detecting if required emulator features are present");
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+ if (!qemuProcessVerifyGuestCPU(driver, vm))
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+ goto cleanup;
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+
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VIR_DEBUG("Detecting VCPU PIDs");
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if (qemuProcessDetectVcpuPIDs(driver, vm) < 0)
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goto cleanup;
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--
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1.8.4.2
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