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    Subject[PATCH 4.9 056/310] KVM: arm64: Restore host physical timer access on hyp_panic()
    Date
    4.9-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: James Morse <james.morse@arm.com>


    [ Upstream commit e8ec032b182cd4841605de4fc297a8edffe55972 ]

    When KVM panics, it hurridly restores the host context and parachutes
    into the host's panic() code. At some point panic() touches the physical
    timer/counter. Unless we are an arm64 system with VHE, this traps back
    to EL2. If we're lucky, we panic again.

    Add a __timer_save_state() call to KVMs hyp_panic() path, this saves the
    guest registers and disables the traps for the host.

    Fixes: 53fd5b6487e4 ("arm64: KVM: Add panic handling")
    Signed-off-by: James Morse <james.morse@arm.com>
    Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
    Reviewed-by: Christoffer Dall <cdall@linaro.org>
    Signed-off-by: Christoffer Dall <cdall@linaro.org>
    Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    arch/arm64/kvm/hyp/switch.c | 1 +
    1 file changed, 1 insertion(+)

    --- a/arch/arm64/kvm/hyp/switch.c
    +++ b/arch/arm64/kvm/hyp/switch.c
    @@ -404,6 +404,7 @@ void __hyp_text __noreturn __hyp_panic(v

    vcpu = (struct kvm_vcpu *)read_sysreg(tpidr_el2);
    host_ctxt = kern_hyp_va(vcpu->arch.host_cpu_context);
    + __timer_save_state(vcpu);
    __deactivate_traps(vcpu);
    __deactivate_vm(vcpu);
    __sysreg_restore_host_state(host_ctxt);

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