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    SubjectRe: [PATCH] KVM: x86/mmu: Do not create SPTEs for GFNs that exceed host.MAXPHYADDR
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    On Tue, 2022-05-03 at 12:12 +0300, Maxim Levitsky wrote:
    > On Mon, 2022-05-02 at 16:51 +0000, Sean Christopherson wrote:
    > > On Mon, May 02, 2022, Maxim Levitsky wrote:
    > > > On Mon, 2022-05-02 at 10:59 +0300, Maxim Levitsky wrote:
    > > > > > > Also I can reproduce it all the way to 5.14 kernel (last kernel I have installed in this VM).
    > > > > > >
    > > > > > > I tested kvm/queue as of today, sadly I still see the warning.
    > > > > >
    > > > > > Due to a race, the above statements are out of order ;-)
    > > > >
    > > > > So futher investigation shows that the trigger for this *is* cpu_pm=on :(
    > > > >
    > > > > So this is enough to trigger the warning when run in the guest:
    > > > >
    > > > > qemu-system-x86_64 -nodefaults -vnc none -serial stdio -machine accel=kvm
    > > > > -kernel x86/dummy.flat -machine kernel-irqchip=on -smp 8 -m 1g -cpu host
    > > > > -overcommit cpu-pm=on
    > > > >
    > > > >
    > > > > '-smp 8' is needed, and the more vCPUs the more often the warning appears.
    > > > >
    > > > >
    > > > > Due to non atomic memslot update bug, I use patched qemu version, with an
    > > > > attached hack, to pause/resume vcpus around the memslot update it does, but
    > > > > even without this hack, you can just ctrl+c the test after it gets the KVM
    > > > > internal error, and then tdp mmu memory leak warning shows up (not always
    > > > > but very often).
    > > > >
    > > > >
    > > > > Oh, and if I run the above command on the bare metal, it never terminates.
    > > > > Must be due to preemption, qemu shows beeing stuck in kvm_vcpu_block. AVIC
    > > > > disabled, kvm/queue. Bugs, bugs, and features :)
    > > >
    > > > All right, at least that was because I removed the '-device isa-debug-exit,iobase=0xf4,iosize=0x4',
    > > > which is apparently used by KVM unit tests to signal exit from the VM.
    > >
    > > Can you provide your QEMU command line for running your L1 VM? And your L0 and L1
    > > Kconfigs too? I've tried both the dummy and ipi_stress tests on a variety of hardware,
    > > kernels, QEMUs, etc..., with no luck.
    > >
    >
    > So now both L0 and L1 run almost pure kvm/queue)
    > (commit 2764011106d0436cb44702cfb0981339d68c3509)
    >
    > I have some local patches but they are not relevant to KVM at all, more
    > like various tweaks to sensors, a sad hack for yet another regression
    > in AMDGPU, etc.
    >
    > The config and qemu command line attached.
    >
    > AVIC disabled in L0, L0 qemu is from master upstream.
    > Bug reproduces too well IMHO, almost always.
    >
    > For reference the warning is printed in L1's dmesg.

    Tested this without any preemption in L0 and L1 - bug still reproduces just fine.
    (kvm/queue)

    Best regards,
    Maxim Levitsky

    >
    >
    >
    > Best regards,
    > Maxim Levitsky


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