On 2015-11-10 07:22, Paolo Bonzini wrote:
I just finished running a couple of tests in a KVM instance running nested on a Xen HVM instance, and found no issues, so for the set as a whole:Yes, these can happen. The issue is that benign exceptions are delivered serially, but two of them (#DB and #AC) can also happen during exception delivery itself. The subsequent infinite stream of exceptions causes the processor to never exit guest mode.Paolo Eric Northup (1): KVM: x86: work around infinite loop in microcode when #AC is delivered Paolo Bonzini (2): KVM: svm: unconditionally intercept #DB KVM: x86: rename update_db_bp_intercept to update_bp_intercept arch/x86/include/asm/kvm_host.h | 2 +- arch/x86/include/uapi/asm/svm.h | 1 + arch/x86/kvm/svm.c | 22 +++++++++++----------- arch/x86/kvm/vmx.c | 7 +++++-- arch/x86/kvm/x86.c | 2 +- 5 files changed, 19 insertions(+), 15 deletions(-)
Tested-by: Austin S. Hemmelgarn <ahferro...@gmail.com>Now to hope the equivalent fix for Xen gets into the Gentoo repositories soon, as the issue propagates down through nested virtualization and ties up the CPU regardless (and in turn triggers the watchdog).
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