On Thu, Oct 15, 2020 at 02:52:34PM +0100, Marc Zyngier wrote: > On 2020-10-15 14:35, Andrew Jones wrote: > > On Thu, Oct 15, 2020 at 12:26:10PM +0100, Marc Zyngier wrote: > > > Hi > > > > > > Please don't use my arm.com address anymore, nobody reads it... > > > > > > On 2020-10-15 05:06, 张东旭 wrote: > > > > I'm so sorry for disturbing you. > > > > > > > > When I apply this kernel patch：KVM: arm64/sve: System register > > > > context switch and access support > > > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/arch/arm64/kvm/sys_regs.c?id=73433762fcaeb9d59e84d299021c6b15466c96dd > > > > > > This patch was only introduced in 5.2, and wasn't supposed to be > > > backported to anything else. > > > > All upstream patches are backport candidates. Welcome to RHEL :-) > > Great! RHEL gets to keep the pieces! ;-) > > > > > > > > > > qemu live migration will failed with messages： > > > > qemu-kvm: Invalid value 233 expecting positive value > > > > <= 232 > > > > qemu-kvm: Failed to load cpu:cpreg_vmstate_array_len > > > > New version kernel exclude ID_AA64ZFR0_EL1 register when host not > > > > support SVE feature, > > > > so qemu ioctl kvm(KVM_GET_REG_LIST) will not contain ID_AA64ZFR0_EL1 > > > > register. > > > > > > > > I'm using CentOS Linux kernel, old kernel version：4.18.0-80.11.el8 > > > > (migration source) > > > > new kernel version：4.18.0-147.5.el8 (migration destination) > > > > > > > > CentOS linux kernel version 4.18.0-111.el8 applied this patch. So > > > > 4.18.0-147.5.el8 also applied this patch. > > > > > > > > Migration source and destination hosts have the same hardware, just > > > > kernel version is different, > > > > and the hardware on either side of the migration not support SVE. > > > > > > > > Is there some good suggestions，which can make sure old version > > > > kernel live migration to new version kernel with qemu? > > > > > > I['m afraid you should take this with your distribution of > > > choice, unless you can reproduce the problem with mainline kernels. > > > > I'll bet this reproduces when migrating from a mainline pre SVE register > > filtering kernel to a mainline that does the filtering. I don't have > > time to test that though. > > Probably. I'm not really sure where to find SVE HW though, other > than emulation... > The reporter states neither the source nor destination hardware supports SVE. My guess is that what's happening is the reserved ID register ID_UNALLOCATED(4,4) was showing up in the KVM_GET_REG_LIST count on the old kernel, but the new kernel filters it out. Maybe it is a bug to filter it out of the count, as it's a reserved ID register and I suppose the other reserved ID registers are still showing up? Thanks, drew _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
