On 05/16/2012 10:50 AM, zhangyanfei wrote: > This patch set exports offsets of VMCS fields as note information for > kdump. We call it VMCSINFO. The purpose of VMCSINFO is to retrieve > runtime state of guest machine image, such as registers, in host > machine's crash dump as VMCS format. The problem is that VMCS internal > is hidden by Intel in its specification. So, we slove this problem > by reverse engineering implemented in this patch set. The VMCSINFO > is exported via sysfs to kexec-tools just like VMCOREINFO. > > Here are two usercases for two features that we want. > > 1) Create guest machine's crash dumpfile from host machine's crash dumpfile > > In general, we want to use this feature on failure analysis for the system > where the processing depends on the communication between host and guest > machines to look into the system from both machines's viewpoints. > > As a concrete situation, consider where there's heartbeat monitoring > feature on the guest machine's side, where we need to determine in > which machine side the cause of heartbeat stop lies. In our actual > experiments, we encountered such situation and we found the cause of > the bug was in host's process schedular so guest machine's vcpu stopped > for a long time and then led to heartbeat stop. > > The module that judges heartbeat stop is on guest machine, so we need > to debug guest machine's data. But if the cause lies in host machine > side, we need to look into host machine's crash dump. Do you mean, that a heartbeat failure in the guest lead to host panic? My expectation is that a problem in the guest will cause the guest to panic and perhaps produce a dump; the host will remain up. > Without this feature, we first create guest machine's dump and then > create host mahine's, but there's only a short time between two > processings, during which it's unlikely that buggy situation remains. > > So, we think the feature is useful to debug both guest machine's and > host machine's sides at the same time, and expect we can make failure > analysis efficiently. > > Of course, we believe this feature is commonly useful on the situation > where guest machine doesn't work well due to something of host machine's. > > 2) Get offsets of VMCS information on the CPU running on the host machine > > If kdump doesn't work well, then it means we cannot use kvm API to get > register values of guest machine and they are still left on its vmcs > region. In the case, we use crash dump mechanism running outside of > linux kernel, such as sadump, a firmware-based crash dump. Then VMCS > information is then necessary. Shouldn't sadump then expose the VMCS offsets? Perhaps bundling them into its dump file? -- error compiling committee.c: too many arguments to function -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
