[libvirt] [PATCH RFC 2/5] libxl: describe host cpu features based on hwcaps
Joao Martins
joao.m.martins at oracle.com
Fri Jul 8 16:16:32 UTC 2016
Parse libxl_hwcaps accounting for versions for Xen 4.4.
libxl_hwcaps is a set of cpuid leaves output that is described in [0] or
[1] in Xen 4.7. This is a collection of CPUID leaves that are we version
in libvirt whenever leaves are reordered or added. Thus we keep the
common ones in one struct and others for each version. Since
libxl_hwcaps doesn't appear to have a stable format across all supported
versions thus we need to keep track of changes as a compromise whenever
these extracting host featuresets are exported by libxl. Also we don't
fail in initializing the driver in case parsing of hwcaps failed.
xen/include/asm-x86/cpufeature.h
include/public/arch-x86/cpufeatureset.h
Signed-off-by: Joao Martins <joao.m.martins at oracle.com>
---
Probably to make it easier to extend hwcaps handling in the future may
be it's better to introduce an enum for the version and restructure this
in another way?
---
src/libxl/libxl_capabilities.c | 106 +++++++++++++++++++++++++++++++++++++++--
1 file changed, 103 insertions(+), 3 deletions(-)
diff --git a/src/libxl/libxl_capabilities.c b/src/libxl/libxl_capabilities.c
index f71fd3b..c0857e5 100644
--- a/src/libxl/libxl_capabilities.c
+++ b/src/libxl/libxl_capabilities.c
@@ -36,6 +36,8 @@
#include "domain_capabilities.h"
#include "vircommand.h"
#include "libxl_capabilities.h"
+#include "cpu/cpu_x86.h"
+#include "cpu/cpu_x86_data.h"
#define VIR_FROM_THIS VIR_FROM_LIBXL
@@ -43,7 +45,8 @@
VIR_LOG_INIT("libxl.libxl_capabilities");
/* see xen-unstable.hg/xen/include/asm-x86/cpufeature.h */
-#define LIBXL_X86_FEATURE_PAE_MASK 0x40
+#define LIBXL_X86_FEATURE_PAE_MASK (1 << 6)
+#define LIBXL_X86_FEATURE_LM_MASK (1 << 29)
struct guest_arch {
@@ -57,17 +60,94 @@ struct guest_arch {
#define XEN_CAP_REGEX "(xen|hvm)-[[:digit:]]+\\.[[:digit:]]+-(aarch64|armv7l|x86_32|x86_64|ia64|powerpc64)(p|be)?"
+static int
+libxlCapsAddCPUID(virCPUx86Data *data, virCPUx86CPUID *cpuid, ssize_t ncaps)
+{
+ size_t i;
+
+ for (i = 0; i < ncaps; i++) {
+ virCPUx86CPUID *c = &cpuid[i];
+
+ if (virCPUx86DataAddCPUID(data, c) < 0) {
+ VIR_DEBUG("Failed to add CPUID(%x,%x)", c->eax_in, c->ecx_in);
+ return -1;
+ }
+ }
+
+ return 0;
+}
+
+/*
+ * The words represented in physinfo.hw_cap are host CPUID (sub) leafs.
+ * Position of these hasn't changed much up until Xen 4.7 with a rework
+ * on how CPUID is handled internally. As a side-effect it got normalized
+ * and also added more feature words. Although cannot be relied upon as
+ * stable interface, and hence we version changes in position of the features
+ * across all supported versions of the libxl driver until libxl exposes a
+ * stable representation of these capabilities. Fortunately not a lot of
+ * variation happened so it's still possible to keep track of these leafs
+ * to describe host CPU in libvirt capabilities. v0 is for Xen 4.4 up to 4.6,
+ * while v1 is meant for Xen 4.7, as depicted in the table below:
+ *
+ * | v0 (Xen 4.4 - 4.6) | v1 (Xen >= 4.7) |
+ * ---------------------------------------------
+ * word 0 | CPUID.00000001.EDX | CPUID.00000001.EDX |
+ * word 1 | CPUID.80000001.EDX | CPUID.00000001.ECX |
+ * word 2 | CPUID.80860001 | CPUID.80000001.EDX |
+ * word 3 | - Linux - | CPUID.80000001.ECX |
+ * word 4 | CPUID.00000001.ECX | CPUID.0000000D:1.EAX |
+ * word 5 | CPUID.C0000001 | CPUID.00000007:0.EBX |
+ * word 6 | CPUID.80000001.ECX | CPUID.00000007:0.ECX |
+ * word 7 | CPUID.00000007.EBX | CPUID.80000007.EDX |
+ * word 8 | - Non existent - | CPUID.80000008.EBX |
+ *
+ */
+static virCPUDataPtr
+libxlCapsNodeData(virCPUDefPtr cpu, libxl_hwcap hwcap, unsigned version)
+{
+ ssize_t ncaps;
+ virCPUx86Data data = VIR_CPU_X86_DATA_INIT;
+ virCPUx86CPUID cpuid[] = {
+ { .eax_in = 0x00000001, .edx = hwcap[0] },
+ { .eax_in = 0x00000001, .ecx = (version > 0 ? hwcap[1] : hwcap[4]) },
+ { .eax_in = 0x80000001, .edx = (version > 0 ? hwcap[2] : hwcap[1]) },
+ { .eax_in = 0x80000001, .ecx = (version > 0 ? hwcap[3] : hwcap[6]) },
+ { .eax_in = 0x00000007, .ebx = (version > 0 ? hwcap[5] : hwcap[7]) }
+ };
+ virCPUx86CPUID cpuid_ver1[] = {
+ { .eax_in = 0x0000000D, .ecx_in = 1U, .eax = hwcap[4] },
+ { .eax_in = 0x00000007, .ecx_in = 0U, .ecx = hwcap[6] },
+ { .eax_in = 0x80000007, .ecx_in = 0U, .edx = hwcap[7] },
+ };
+
+ ncaps = ARRAY_CARDINALITY(cpuid);
+ if (libxlCapsAddCPUID(&data, cpuid, ncaps) < 0)
+ return NULL;
+
+ ncaps = ARRAY_CARDINALITY(cpuid_ver1);
+ if (version > 0 && libxlCapsAddCPUID(&data, cpuid_ver1, ncaps) < 0)
+ return NULL;
+
+ return virCPUx86MakeData(cpu->arch, &data);
+}
+
/* hw_caps is an array of 32-bit words whose meaning is listed in
* xen-unstable.hg/xen/include/asm-x86/cpufeature.h. Each feature
* is defined in the form X*32+Y, corresponding to the Y'th bit in
* the X'th 32-bit word of hw_cap.
*/
static int
-libxlCapsInitCPU(virCapsPtr caps, libxl_physinfo *phy_info)
+libxlCapsInitCPU(virCapsPtr caps, libxl_physinfo *phy_info, unsigned version)
{
virCPUDefPtr cpu = NULL;
+ virCPUDataPtr data = NULL;
int ret = -1;
int host_pae;
+ int host_lm;
+
+ /* parse hw_cap only for x86 */
+ if (!phy_info->hw_cap[0])
+ return 0;
if (VIR_ALLOC(cpu) < 0)
goto error;
@@ -77,15 +157,26 @@ libxlCapsInitCPU(virCapsPtr caps, libxl_physinfo *phy_info)
virCapabilitiesAddHostFeature(caps, "pae") < 0)
goto error;
+ host_lm = phy_info->hw_cap[version > 0 ? 2 : 1] & LIBXL_X86_FEATURE_LM_MASK;
+ if (host_lm)
+ cpu->arch = VIR_ARCH_X86_64;
+ else
+ cpu->arch = VIR_ARCH_I686;
+
cpu->type = VIR_CPU_TYPE_HOST;
cpu->cores = phy_info->cores_per_socket;
cpu->threads = phy_info->threads_per_core;
cpu->sockets = phy_info->nr_cpus / (cpu->cores * cpu->threads);
caps->host.cpu = cpu;
+ if (!(data = libxlCapsNodeData(cpu, phy_info->hw_cap, version))
+ || cpuDecode(cpu, data, NULL, 0, NULL) < 0)
+ goto cleanup;
+
ret = 0;
cleanup:
+ cpuDataFree(data);
return ret;
@@ -97,7 +188,9 @@ libxlCapsInitCPU(virCapsPtr caps, libxl_physinfo *phy_info)
static int
libxlCapsInitHost(libxl_ctx *ctx, virCapsPtr caps)
{
+ const libxl_version_info *ver_info;
libxl_physinfo phy_info;
+ unsigned version;
if (libxl_get_physinfo(ctx, &phy_info) != 0) {
virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
@@ -105,8 +198,15 @@ libxlCapsInitHost(libxl_ctx *ctx, virCapsPtr caps)
return -1;
}
- if (libxlCapsInitCPU(caps, &phy_info) < 0)
+ if ((ver_info = libxl_get_version_info(ctx)) == NULL) {
+ virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+ _("Failed to get version info from libxenlight"));
return -1;
+ }
+
+ version = (ver_info->xen_version_minor >= 7);
+ if (libxlCapsInitCPU(caps, &phy_info, version) < 0)
+ VIR_WARN("Failed to initialize host cpu data");
if (virCapabilitiesSetNetPrefix(caps, LIBXL_GENERATED_PREFIX_XEN) < 0)
return -1;
--
2.1.4
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