On 31 July 2014 17:57, Paolo Bonzini <pbonzini@xxxxxxxxxx> wrote: > Il 09/07/2014 15:55, Alex Bennée ha scritto: >> To cleanly restore an SMP VM we need to ensure that the current pause >> state of each vcpu is correctly recorded. Things could get confused if >> the CPU starts running after migration restore completes when it was >> paused before it state was captured. >> >> I've done this by exposing a register (currently only 1 bit used) via >> the GET/SET_ONE_REG logic to pass the state between KVM and the VM >> controller (e.g. QEMU). >> >> Signed-off-by: Alex Bennée <alex.bennee@xxxxxxxxxx> >> --- >> arch/arm64/include/uapi/asm/kvm.h | 8 +++++ >> arch/arm64/kvm/guest.c | 61 ++++++++++++++++++++++++++++++++++++++- >> 2 files changed, 68 insertions(+), 1 deletion(-) > > Since it's a pseudo register anyway, would it make sense to use the > existing KVM_GET/SET_MP_STATE ioctl interface? That appears to be an x86-specific thing relating to IRQ chips. > How is this represented within QEMU in TCG mode? We don't implement it in TCG yet; Rob Herring has posted patches but they had a few minor issues (didn't compile on non-Linux hosts). The answer will be 'in a "bool powered_off" flag in struct ARMCPU'. > Also, how is KVM/ARM > representing (and passing to QEMU) the halted state of the > VCPU? We don't. In ARM the equivalent of x86 HLT (which is WFI, wait-for-interrupt) is allowed to resume at any time. So we don't need to care about saving and restoring whether we were sat in a WFI at point of migration. thanks -- PMM -- 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
