On Mon, Apr 08, 2019 at 10:42:38AM +0200, Jiri Denemark wrote:
The new virHostCPUGetMSR internal API will try to read the MSR from /dev/cpu/0/msr and if it is not possible (the device does not exist or libvirt is running unprivileged), it will fallback to asking KVM for the MSR using KVM_GET_MSRS ioctl.
Signed-off-by: Jiri Denemark <jdenemar@redhat.com> --- src/libvirt_private.syms | 1 + src/util/virhostcpu.c | 80 ++++++++++++++++++++++++++++++++++++++++ src/util/virhostcpu.h | 3 ++ 3 files changed, 84 insertions(+)
diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms index 132ee3cae9..59a9a6f093 100644 --- a/src/libvirt_private.syms +++ b/src/libvirt_private.syms @@ -2016,6 +2016,7 @@ virHostCPUGetInfo; virHostCPUGetKVMMaxVCPUs; virHostCPUGetMap; virHostCPUGetMicrocodeVersion; +virHostCPUGetMSR;
Hi, This breaks build on powerpc too. CC util/libvirt_util_la-virhook.lo CC util/libvirt_util_la-virhostcpu.lo util/virhostcpu.c: In function 'virHostCPUGetMSRFromKVM': util/virhostcpu.c:1267:25: error: field 'header' has incomplete type 1267 | struct kvm_msrs header; 2019-04-15 01:06:28,740 process L0458 DEBUG| [stdout] make[3]: Leaving directory '/usr/share/avocado-plugins-vt/build/libvirt/src' | ^~~~~~ 2019-04-15 01:06:28,741 process L0458 DEBUG| [stdout] make[2]: Leaving directory '/usr/share/avocado-plugins-vt/build/libvirt/src' util/virhostcpu.c:1268:30: error: field 'entry' has incomplete type 2019-04-15 01:06:28,742 process L0714 INFO | Command 'make' finished with 2 after 27.617787838s 2019-04-15 01:06:28,742 process L0458 DEBUG| [stdout] make[1]: Leaving directory '/usr/share/avocado-plugins-vt/build/libvirt' 1268 | struct kvm_msr_entry entry; | ^~~~~ util/virhostcpu.c:1270:21: error: field name not in record or union initializer 1270 | .header = { .nmsrs = 1 }, | ^ util/virhostcpu.c:1270:21: note: (near initialization for 'msr.header') util/virhostcpu.c:1271:20: error: field name not in record or union initializer 1271 | .entry = { .index = index }, | ^ util/virhostcpu.c:1271:20: note: (near initialization for 'msr.entry') In file included from /usr/include/asm/ioctl.h:12, from /usr/include/asm/ioctls.h:5, from /usr/include/bits/ioctls.h:23, from /usr/include/sys/ioctl.h:26, from ../gnulib/lib/sys/ioctl.h:27, from util/virhostcpu.c:27: util/virhostcpu.c:1279:19: error: invalid application of 'sizeof' to incomplete type 'struct kvm_msrs' 1279 | if (ioctl(fd, KVM_GET_MSRS, &msr) < 0) { | ^~~~~~~~~~~~ make[3]: *** [Makefile:11963: util/libvirt_util_la-virhostcpu.lo] Error 1 make[2]: *** [Makefile:7128: all] Error 2 make[1]: *** [Makefile:2257: all-recursive] Error 1 make: *** [Makefile:2149: all] Error 2 Regards, -Satheesh
virHostCPUGetOnline; virHostCPUGetOnlineBitmap; virHostCPUGetPresentBitmap; diff --git a/src/util/virhostcpu.c b/src/util/virhostcpu.c index 6514c3d765..10bf3a93d5 100644 --- a/src/util/virhostcpu.c +++ b/src/util/virhostcpu.c @@ -58,6 +58,7 @@ VIR_LOG_INIT("util.hostcpu");
#define KVM_DEVICE "/dev/kvm" +#define MSR_DEVICE "/dev/cpu/0/msr"
#if defined(__FreeBSD__) || defined(__APPLE__) @@ -1254,3 +1255,82 @@ virHostCPUGetMicrocodeVersion(void) }
#endif /* __linux__ */ + + +#if HAVE_LINUX_KVM_H && defined(KVM_GET_MSRS) +static int +virHostCPUGetMSRFromKVM(unsigned long index, + uint64_t *result) +{ + VIR_AUTOCLOSE fd = -1; + struct { + struct kvm_msrs header; + struct kvm_msr_entry entry; + } msr = { + .header = { .nmsrs = 1 }, + .entry = { .index = index }, + }; + + if ((fd = open(KVM_DEVICE, O_RDONLY)) < 0) { + virReportSystemError(errno, _("Unable to open %s"), KVM_DEVICE); + return -1; + } + + if (ioctl(fd, KVM_GET_MSRS, &msr) < 0) { + VIR_DEBUG("Cannot get MSR 0x%lx from KVM", index); + return 1; + } + + *result = msr.entry.data; + return 0; +} + +#else + +static int +virHostCPUGetMSRFromKVM(unsigned long index ATTRIBUTE_UNUSED, + uint64_t *result ATTRIBUTE_UNUSED) +{ + virReportSystemError(ENOSYS, "%s", + _("Reading MSRs via KVM is not supported on this platform")); + return -1; +} +#endif /* HAVE_LINUX_KVM_H && defined(KVM_GET_MSRS) */ + + +/* + * Returns 0 on success, + * 1 when the MSR is not supported by the host CPU, +* -1 on error. + */ +int +virHostCPUGetMSR(unsigned long index, + uint64_t *msr) +{ + VIR_AUTOCLOSE fd = -1; + char ebuf[1024]; + + *msr = 0; + + if ((fd = open(MSR_DEVICE, O_RDONLY)) < 0) { + VIR_DEBUG("Unable to open %s: %s", + MSR_DEVICE, virStrerror(errno, ebuf, sizeof(ebuf))); + } else { + int rc = pread(fd, msr, sizeof(*msr), index); + + if (rc == sizeof(*msr)) + return 0; + + if (rc < 0 && errno == EIO) { + VIR_DEBUG("CPU does not support MSR 0x%lx", index); + return 1; + } + + VIR_DEBUG("Cannot read MSR 0x%lx from %s: %s", + index, MSR_DEVICE, virStrerror(errno, ebuf, sizeof(ebuf))); + } + + VIR_DEBUG("Falling back to KVM ioctl"); + + return virHostCPUGetMSRFromKVM(index, msr); +} diff --git a/src/util/virhostcpu.h b/src/util/virhostcpu.h index df6a7e789d..0d20dbef61 100644 --- a/src/util/virhostcpu.h +++ b/src/util/virhostcpu.h @@ -66,4 +66,7 @@ int virHostCPUGetOnline(unsigned int cpu, bool *online);
unsigned int virHostCPUGetMicrocodeVersion(void);
+int virHostCPUGetMSR(unsigned long index, + uint64_t *msr); + #endif /* LIBVIRT_VIRHOSTCPU_H */ -- 2.21.0
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