Re: [libvirt] [PATCHv3 2/6] qemu: Add monitor APIs to fetch CPUID data from QEMU

From: Jiri Denemark <jdenemar(a)redhat.com&gt; The qemu monitor supports retrieval of actual CPUID bits presented to the guest using QMP monitor. Add APIs to extract these information and tests for them. Signed-off-by: Peter Krempa <pkrempa(a)redhat.com&gt; ---

diff --git a/src/qemu/qemu_monitor_json.c b/src/qemu/qemu_monitor_json.c index 05f8aa6..e738fe3 100644 --- a/src/qemu/qemu_monitor_json.c +++ b/src/qemu/qemu_monitor_json.c @@ -42,6 +42,7 @@ #include "virerror.h" #include "virjson.h" #include "virstring.h" +#include "cpu/cpu_x86.h" #ifdef WITH_DTRACE_PROBES # include "libvirt_qemu_probes.h" @@ -49,6 +50,7 @@ #define VIR_FROM_THIS VIR_FROM_QEMU +#define QOM_CPU_PATH "/machine/unattached/device[0]" #define LINE_ENDING "\r\n" @@ -5454,3 +5456,134 @@ cleanup: VIR_FREE(paths); return ret; } + + +static int +qemuMonitorJSONParseCPUx86FeatureWord(virJSONValuePtr data, + virCPUx86CPUID *cpuid) +{ + const char *reg; + unsigned long long fun; + unsigned long long features; + + memset(cpuid, 0, sizeof(*cpuid)); + + if (!(reg = virJSONValueObjectGetString(data, "cpuid-register"))) { + virReportError(VIR_ERR_INTERNAL_ERROR, "%s", + _("missing cpuid-register in CPU data")); + return -1; + } + if (virJSONValueObjectGetNumberUlong(data, "cpuid-input-eax", &fun)) { + virReportError(VIR_ERR_INTERNAL_ERROR, "%s", + _("missing or invalid cpuid-input-eax in CPU data")); + return -1; + } + if (virJSONValueObjectGetNumberUlong(data, "features", &features) < 0) { + virReportError(VIR_ERR_INTERNAL_ERROR, "%s", + _("missing or invalid features in CPU data")); + return -1; + } + + cpuid->function = fun; + if (STREQ(reg, "EAX")) { + cpuid->eax = features; + } else if (STREQ(reg, "EBX")) { + cpuid->ebx = features; + } else if (STREQ(reg, "ECX")) { + cpuid->ecx = features; + } else if (STREQ(reg, "EDX")) { + cpuid->edx = features; + } else { + virReportError(VIR_ERR_INTERNAL_ERROR, + _("unknown CPU register '%s'"), reg); + return -1; + } + + return 0; +} + + +static virCPUDataPtr +qemuMonitorJSONGetCPUx86Data(qemuMonitorPtr mon, + const char *property) +{ + virJSONValuePtr cmd; + virJSONValuePtr reply = NULL; + virJSONValuePtr data; + virCPUx86Data *x86Data = NULL; + virCPUx86CPUID cpuid; + size_t i; + virCPUDataPtr ret = NULL; + int n; + + if (!(cmd = qemuMonitorJSONMakeCommand("qom-get", + "s:path", QOM_CPU_PATH, + "s:property", property, + NULL))) + return NULL; + + if (qemuMonitorJSONCommand(mon, cmd, &reply) < 0) + goto cleanup; + + if (qemuMonitorJSONCheckError(cmd, reply)) + goto cleanup; + + if (!(data = virJSONValueObjectGet(reply, "return"))) { + virReportError(VIR_ERR_INTERNAL_ERROR, "%s", + _("qom-get reply was missing return data")); + goto cleanup; + } + + if ((n = virJSONValueArraySize(data)) < 0) { + virReportError(VIR_ERR_INTERNAL_ERROR, + _("%s CPU property did not return an array"), + property); + goto cleanup; + } + + if (VIR_ALLOC(x86Data) < 0) + goto cleanup; + + for (i = 0; i < n; i++) { + if (qemuMonitorJSONParseCPUx86FeatureWord(virJSONValueArrayGet(data, i), + &cpuid) < 0 || + virCPUx86DataAddCPUID(x86Data, &cpuid) < 0) + goto cleanup; + } + + if (!(ret = virCPUx86MakeData(VIR_ARCH_X86_64, &x86Data))) + goto cleanup; + +cleanup: + virJSONValueFree(cmd); + virJSONValueFree(reply); + virCPUx86DataFree(x86Data); + return ret; +} + + +/** + * qemuMonitorJSONGetGuestCPU: + * @mon: Pointer to the monitor + * @arch: arch of the guest + * + * Retrieve the definition of the guest CPU from a running qemu instance. + * + * Returns the cpu definition object. On error returns NULL. + */ +virCPUDataPtr +qemuMonitorJSONGetGuestCPU(qemuMonitorPtr mon, + virArch arch) +{ + switch (arch) { + case VIR_ARCH_X86_64: + case VIR_ARCH_I686: + return qemuMonitorJSONGetCPUx86Data(mon, "feature-words");

+ + default: + virReportError(VIR_ERR_INTERNAL_ERROR, + _("CPU definition retrieval isn't supported for '%s'"), + virArchToString(arch)); + return NULL; + } +}