• James Morse's avatar
    arm64: kvm: Fix kvm teardown for systems using the extended idmap · c612505f
    James Morse authored
    If memory is located above 1<<VA_BITS, kvm adds an extra level to its page
    tables, merging the runtime tables and boot tables that contain the idmap.
    This lets us avoid the trampoline dance during initialisation.
    This also means there is no trampoline page mapped, so
    __cpu_reset_hyp_mode() can't call __kvm_hyp_reset() in this page. The good
    news is the idmap is still mapped, so we don't need the trampoline page.
    The bad news is we can't call it directly as the idmap is above
    HYP_PAGE_OFFSET, so its address is masked by kvm_call_hyp.
    Add a function __extended_idmap_trampoline which will branch into
    __kvm_hyp_reset in the idmap, change kvm_hyp_reset_entry() to return
    this address if __kvm_cpu_uses_extended_idmap(). In this case
    __kvm_hyp_reset() will still switch to the boot tables (which are the
    merged tables that were already in use), and branch into the idmap (where
    it already was).
    This fixes boot failures on these systems, where we fail to execute the
    missing trampoline page when tearing down kvm in init_subsystems():
    [    2.508922] kvm [1]: 8-bit VMID
    [    2.512057] kvm [1]: Hyp mode initialized successfully
    [    2.517242] kvm [1]: interrupt-controller@e1140000 IRQ13
    [    2.522622] kvm [1]: timer IRQ3
    [    2.525783] Kernel panic - not syncing: HYP panic:
    [    2.525783] PS:200003c9 PC:0000007ffffff820 ESR:86000005
    [    2.525783] FAR:0000007ffffff820 HPFAR:00000000003ffff0 PAR:0000000000000000
    [    2.525783] VCPU:          (null)
    [    2.525783]
    [    2.547667] CPU: 0 PID: 0 Comm: swapper/0 Tainted: G        W       4.6.0-rc5+ #1
    [    2.555137] Hardware name: Default string Default string/Default string, BIOS ROD0084E 09/03/2015
    [    2.563994] Call trace:
    [    2.566432] [<ffffff80080888d0>] dump_backtrace+0x0/0x240
    [    2.571818] [<ffffff8008088b24>] show_stack+0x14/0x20
    [    2.576858] [<ffffff80083423ac>] dump_stack+0x94/0xb8
    [    2.581899] [<ffffff8008152130>] panic+0x10c/0x250
    [    2.586677] [<ffffff8008152024>] panic+0x0/0x250
    [    2.591281] SMP: stopping secondary CPUs
    [    3.649692] SMP: failed to stop secondary CPUs 0-2,4-7
    [    3.654818] Kernel Offset: disabled
    [    3.658293] Memory Limit: none
    [    3.661337] ---[ end Kernel panic - not syncing: HYP panic:
    [    3.661337] PS:200003c9 PC:0000007ffffff820 ESR:86000005
    [    3.661337] FAR:0000007ffffff820 HPFAR:00000000003ffff0 PAR:0000000000000000
    [    3.661337] VCPU:          (null)
    [    3.661337]
    Reported-by: default avatarWill Deacon <will.deacon@arm.com>
    Reviewed-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
    Signed-off-by: default avatarJames Morse <james.morse@arm.com>
    Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
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