Re: [PATCH 3/5] lscpu: detect OS/400 and pHyp hypervisors

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On 22.05.14 11:08, Heiko Carstens wrote:
Hi Karel,

I think Alexander Graf (who is kvm on powerpc maintainer) should answer
how he would like to have it classified.

[full quote below]

On Thu, May 22, 2014 at 10:48:20AM +0200, Karel Zak wrote:
  Heiko, can you help us to classify pSeries and iSeries virtualization?
  See below. Is it FULL or PARA virtualization? Thanks!

     Karel

On Thu, May 22, 2014 at 01:03:43AM +0200, Ruediger Meier wrote:
+	[HYPER_OS400]	= "OS/400",
+	[HYPER_PHYP]	= "pHyp"
  };
const int hv_vendor_pci[] = {
@@ -574,6 +577,51 @@ read_hypervisor_cpuid(struct lscpu_desc *desc)
  static void
  read_hypervisor_cpuid(struct lscpu_desc *desc __attribute__((__unused__)))
  {
+#ifdef __powerpc__
+	/* powerpc:
+	 * IBM iSeries: legacy, if /proc/iSeries exists, its para-virtualized on top of OS/400
According to this comment ...

+	 * IBM pSeries: always has a hypervisor
+	 *              if partition-name is "full", its kind of "bare-metal": full-system-partition
+	 *              otherwise its some partition created by Hardware Management Console
+	 *              in any case, its always some sort of HVM
+	 * KVM: "linux,kvm" in /hypervisor/compatible indicates a KVM guest
+	 * Xen: not in use, not detected
+	 */
+	if (path_exist("/proc/iSeries")) {
+		desc->hyper = HYPER_OS400;
+		desc->virtype = VIRT_FULL;
... shouldn't this be VIRT_PARA? Somebody who knows this may correct this.

iSeries is PV, yes. Among others it's also dead :). But I'll let Ben comment.


+	} else if (path_exist(_PATH_PROC_DEVICETREE "/ibm,partition-name")) {
+		FILE *fd;
+		desc->hyper = HYPER_PHYP;
+		desc->virtype = VIRT_FULL;
Maybe more obvious here for pSeries where p seems to stand for para
http://www.ibm.com/developerworks/aix/library/au-syspvirtualization/index.html?S_TACT=105AGX99&S_CMP=CP

This is slightly more complicated. The ibm,partition-name device tree property is defined in sPAPR which is a specification that both pHyp and QEMU implement. Right now QEMU does not expose the ibm,partition-name property, but there's no reason it will stay that way.

There are a few ways we could try to distinguish QEMU's implementation of the pSeries machine and pHyp's implementation of it.

  /proc/device-tree/hmc-managed?

I don't think QEMU will ever implement this property, but at least my pHyp reference VM does. If it's there we can use it as a definite marker that we are in fact running on pHyp.

  /proc/device-tree/chosen/qemu,graphic-width

Only QEMU puts qemu, properties in the chosen directory. At least the current code always sets the graphic-* properties, so if we find one we can safely assume we're running on QEMU. We do not know whether we're running on KVM yet.

Checking on KVM is slightly more tricky. I think we have 2 options:

  1) Check if /proc/device-tree/cpus/*@0/timebase-frequency is 1000000000.

If it is, we're emulated (no KVM). If it's not, we're running with a native CPU (KVM).

  2) Check whether /proc/device-tree/hypervisor/compatible == "linux,kvm"

I have a patch in my queue to make the sPAPR compliant pSeries machine type in QEMU also ePAPR compliant and expose a /hypervisor node. Current versions of QEMU don't do this though, so this would not catch QEMU versions < 2.1.

The nice thing about the ePAPR compliant check is that we'd catch non-pSeries machine types as well. We expose this node on all emulated Mac machines and on FSL e500 style machines.


Alex

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