lkml.org 
[lkml]   [2017]   [Jan]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[RFC 22/55] KVM: arm64: Handle PSCI call from the guest
    Date
    VMs used to execute hvc #0 for the psci call. However, when we come to
    provide virtual EL2 to the VM, the host OS inside the VM also calls
    kvm_call_hyp which is also hvc #0. So, it's hard to differentiate
    between them from the host hypervisor's point of view.

    So, let the VM execute smc for the psci call. On ARMv8.3, even if EL3 is
    not implemented, a smc instruction executed at non-secure EL1 is trapped
    to EL2 if HCR_EL2.TSC==1, rather than being treated as UNDEFINED. So,
    the host hypervisor can handle this psci call without any confusion.

    Signed-off-by: Jintack Lim <jintack@cs.columbia.edu>
    ---
    arch/arm64/kvm/handle_exit.c | 23 +++++++++++++++++++++--
    1 file changed, 21 insertions(+), 2 deletions(-)

    diff --git a/arch/arm64/kvm/handle_exit.c b/arch/arm64/kvm/handle_exit.c
    index 208be16..ce6d2ef 100644
    --- a/arch/arm64/kvm/handle_exit.c
    +++ b/arch/arm64/kvm/handle_exit.c
    @@ -64,8 +64,27 @@ static int handle_hvc(struct kvm_vcpu *vcpu, struct kvm_run *run)

    static int handle_smc(struct kvm_vcpu *vcpu, struct kvm_run *run)
    {
    - kvm_inject_undefined(vcpu);
    - return 1;
    + int ret;
    +
    + /* If imm is non-zero, it's not defined */
    + if (kvm_vcpu_hvc_get_imm(vcpu)) {
    + kvm_inject_undefined(vcpu);
    + return 1;
    + }
    +
    + /*
    + * If imm is zero, it's a psci call.
    + * Note that on ARMv8.3, even if EL3 is not implemented, SMC executed
    + * at Non-secure EL1 is trapped to EL2 if HCR_EL2.TSC==1, rather than
    + * being treated as UNDEFINED.
    + */
    + ret = kvm_psci_call(vcpu);
    + if (ret < 0) {
    + kvm_inject_undefined(vcpu);
    + return 1;
    + }
    +
    + return ret;
    }

    /**
    --
    1.9.1

    \
     
     \ /
      Last update: 2017-01-09 07:37    [W:4.115 / U:0.032 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site