This patch set addresses KVM issue described in Geoff's kexec patch set. http://lists.infradead.org/pipermail/kexec/2015-March/013432.html
The basic approach here is to define a kvm tear-down function and add a reboot hook to gracefully shutdown the 1st kernel. This way, kvm gets free from kexec-specific cleanup and yet we allows future enhancement, like cpu hotplug & building kvm as a module, based on tear-down function. In this sense, patch #1 & #2 actually fix the problem, and #3 & #4 are rather informative.
I confirmed that 1st kernel successfully shut down and 2nd kernel started with the following messages:
kvm [1]: Using HYP init bounce page @8fa52f000 kvm [1]: interrupt-controller@2c02f000 IRQ6 kvm [1]: timer IRQ3 kvm [1]: Hyp mode initialized successfully
test target: Base fast model version: kernel v4.0-rc4 + Geoff's kexec v8
I still have some concerns about the following points. Please let me know if you have any comments:
1) Call kvm_cpu_reset() on non-boot cpus in reboot notifier We don't have to do so in kexec-specific case. But the current code runs the function on each cpu for safety since we use a general reboot hook. 2) Flush D$ in kvm_cpu_reset() Currently doesn't do so because all the cpus are just going to shut down, and we actually flush D$ on boot cpu in Geoff's cpu_reset(). 3) Compatibility with arm implementation Frediano is no longer working on this issue on arm as he left his company. But my approach here is based on a generic interface and can be applied to arm in a similar way.
http://lists.infradead.org/pipermail/linux-arm-kernel/2015-February/322231.h...
AKASHI Takahiro (4): arm64: kvm: add a cpu tear-down function arm64: kexec: fix kvm issue arm64: kvm: add cpu reset hook for cpu hotplug arm64: kvm: add cpu reset at module exit
arch/arm/kvm/arm.c | 54 +++++++++++++++++++++++++++++++++++++ arch/arm/kvm/mmu.c | 16 +++++++++++ arch/arm64/include/asm/kvm_asm.h | 3 +++ arch/arm64/include/asm/kvm_host.h | 11 +++++++- arch/arm64/include/asm/kvm_mmu.h | 3 +++ arch/arm64/include/asm/virt.h | 11 ++++++++ arch/arm64/kvm/Kconfig | 1 - arch/arm64/kvm/hyp-init.S | 41 ++++++++++++++++++++++++++++ arch/arm64/kvm/hyp.S | 29 +++++++++++++++++--- 9 files changed, 163 insertions(+), 6 deletions(-)