On Tue, Aug 30, 2011 at 10:37:13AM -0600, Eric B Munson wrote: > On Tue, Aug 30, 2011 at 06:26, Marcelo Tosatti <mtosatti@xxxxxxxxxx> wrote: > > On Mon, Aug 29, 2011 at 05:27:11PM -0600, Eric B Munson wrote: > >> Currently, when qemu stops a guest kernel that guest will issue a soft lockup > >> message when it resumes. This set provides the ability for qemu to comminucate > >> to the guest that it has been stopped. When the guest hits the watchdog on > >> resume it will check if it was suspended before issuing the warning. > >> > >> Eric B Munson (4): > >> Add flag to indicate that a vm was stopped by the host > >> Add functions to check if the host has stopped the vm > >> Add generic stubs for kvm stop check functions > >> Add check for suspended vm in softlockup detector > >> > >> arch/x86/include/asm/pvclock-abi.h | 1 + > >> arch/x86/include/asm/pvclock.h | 2 ++ > >> arch/x86/kernel/kvmclock.c | 14 ++++++++++++++ > >> include/asm-generic/pvclock.h | 14 ++++++++++++++ > >> kernel/watchdog.c | 12 ++++++++++++ > >> 5 files changed, 43 insertions(+), 0 deletions(-) > >> create mode 100644 include/asm-generic/pvclock.h > >> > >> -- > >> 1.7.4.1 > > > > How is the host supposed to set this flag? > > The hypervisor will set the flag (the second bit in the struct > pvclock_vcpu_time_info.flags field) when it stops the guest. I could > be reading pvclock-abi.h incorrectly, but the way I understand it is > that this structure is used to communicate between hypervisor and > guest. Yes, its awkward though (to have an interface to modify a bit in pvclock->flags from QEMU). Anyway, it appears that all elements to fix this in QEMU without the need for a paravirt interface are available... did you look into my suggestion? > > As mentioned previously, if you save save/restore the offset added to > > kvmclock on stop/cont (and the TSC MSR, forgot to mention that), no > > paravirt infrastructure is required. Which means the issue is also fixed > > for older guests. > > -- 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
