156 lines
4.4 KiB
Diff
156 lines
4.4 KiB
Diff
From 6094ea6111dd57274b6037e76f662a06b8e5c9d1 Mon Sep 17 00:00:00 2001
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Message-Id: <6094ea6111dd57274b6037e76f662a06b8e5c9d1@dist-git>
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From: Jiri Denemark <jdenemar@redhat.com>
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Date: Fri, 21 Jun 2019 09:25:43 +0200
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Subject: [PATCH] vircpuhost: Add support for reading MSRs
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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The new virHostCPUGetMSR internal API will try to read the MSR from
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/dev/cpu/0/msr and if it is not possible (the device does not exist or
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libvirt is running unprivileged), it will fallback to asking KVM for the
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MSR using KVM_GET_MSRS ioctl.
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Signed-off-by: Jiri Denemark <jdenemar@redhat.com>
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Reviewed-by: Ján Tomko <jtomko@redhat.com>
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(cherry picked from commit df4b46737f43a1a67f9b5de2840213a1bd2b3cce)
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https://bugzilla.redhat.com/show_bug.cgi?id=1697627
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Conflicts:
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src/util/virhostcpu.h
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- different header file guard symbol
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Signed-off-by: Jiri Denemark <jdenemar@redhat.com>
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Message-Id: <0d4c18704c435cccc2b18ebd55f4f914caf05d13.1561068591.git.jdenemar@redhat.com>
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Reviewed-by: Ján Tomko <jtomko@redhat.com>
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---
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src/libvirt_private.syms | 1 +
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src/util/virhostcpu.c | 80 ++++++++++++++++++++++++++++++++++++++++
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src/util/virhostcpu.h | 3 ++
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3 files changed, 84 insertions(+)
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diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
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index 347667b17c..9ebc5384fb 100644
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--- a/src/libvirt_private.syms
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+++ b/src/libvirt_private.syms
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@@ -1974,6 +1974,7 @@ virHostCPUGetInfo;
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virHostCPUGetKVMMaxVCPUs;
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virHostCPUGetMap;
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virHostCPUGetMicrocodeVersion;
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+virHostCPUGetMSR;
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virHostCPUGetOnline;
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virHostCPUGetOnlineBitmap;
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virHostCPUGetPresentBitmap;
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diff --git a/src/util/virhostcpu.c b/src/util/virhostcpu.c
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index effe04ca3a..d0c47faa18 100644
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--- a/src/util/virhostcpu.c
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+++ b/src/util/virhostcpu.c
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@@ -64,6 +64,7 @@
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VIR_LOG_INIT("util.hostcpu");
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#define KVM_DEVICE "/dev/kvm"
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+#define MSR_DEVICE "/dev/cpu/0/msr"
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#if defined(__FreeBSD__) || defined(__APPLE__)
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@@ -1266,3 +1267,82 @@ virHostCPUGetMicrocodeVersion(void)
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}
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#endif /* __linux__ */
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+
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+
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+#if HAVE_LINUX_KVM_H && defined(KVM_GET_MSRS)
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+static int
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+virHostCPUGetMSRFromKVM(unsigned long index,
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+ uint64_t *result)
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+{
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+ VIR_AUTOCLOSE fd = -1;
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+ struct {
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+ struct kvm_msrs header;
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+ struct kvm_msr_entry entry;
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+ } msr = {
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+ .header = { .nmsrs = 1 },
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+ .entry = { .index = index },
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+ };
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+
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+ if ((fd = open(KVM_DEVICE, O_RDONLY)) < 0) {
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+ virReportSystemError(errno, _("Unable to open %s"), KVM_DEVICE);
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+ return -1;
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+ }
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+
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+ if (ioctl(fd, KVM_GET_MSRS, &msr) < 0) {
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+ VIR_DEBUG("Cannot get MSR 0x%lx from KVM", index);
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+ return 1;
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+ }
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+
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+ *result = msr.entry.data;
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+ return 0;
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+}
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+
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+#else
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+
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+static int
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+virHostCPUGetMSRFromKVM(unsigned long index ATTRIBUTE_UNUSED,
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+ uint64_t *result ATTRIBUTE_UNUSED)
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+{
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+ virReportSystemError(ENOSYS, "%s",
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+ _("Reading MSRs via KVM is not supported on this platform"));
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+ return -1;
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+}
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+#endif /* HAVE_LINUX_KVM_H && defined(KVM_GET_MSRS) */
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+
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+
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+/*
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+ * Returns 0 on success,
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+ * 1 when the MSR is not supported by the host CPU,
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+* -1 on error.
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+ */
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+int
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+virHostCPUGetMSR(unsigned long index,
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+ uint64_t *msr)
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+{
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+ VIR_AUTOCLOSE fd = -1;
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+ char ebuf[1024];
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+
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+ *msr = 0;
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+
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+ if ((fd = open(MSR_DEVICE, O_RDONLY)) < 0) {
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+ VIR_DEBUG("Unable to open %s: %s",
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+ MSR_DEVICE, virStrerror(errno, ebuf, sizeof(ebuf)));
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+ } else {
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+ int rc = pread(fd, msr, sizeof(*msr), index);
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+
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+ if (rc == sizeof(*msr))
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+ return 0;
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+
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+ if (rc < 0 && errno == EIO) {
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+ VIR_DEBUG("CPU does not support MSR 0x%lx", index);
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+ return 1;
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+ }
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+
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+ VIR_DEBUG("Cannot read MSR 0x%lx from %s: %s",
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+ index, MSR_DEVICE, virStrerror(errno, ebuf, sizeof(ebuf)));
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+ }
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+
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+ VIR_DEBUG("Falling back to KVM ioctl");
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+
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+ return virHostCPUGetMSRFromKVM(index, msr);
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+}
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diff --git a/src/util/virhostcpu.h b/src/util/virhostcpu.h
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index f9f3359288..e705623d4f 100644
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--- a/src/util/virhostcpu.h
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+++ b/src/util/virhostcpu.h
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@@ -68,4 +68,7 @@ int virHostCPUGetOnline(unsigned int cpu, bool *online);
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unsigned int virHostCPUGetMicrocodeVersion(void);
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+int virHostCPUGetMSR(unsigned long index,
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+ uint64_t *msr);
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+
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#endif /* __VIR_HOSTCPU_H__*/
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--
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2.22.0
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