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    SubjectRe: [PATCH v4 06/21] KVM: arm64: Support SDEI_EVENT_CONTEXT hypercall
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    Hi Eric,

    On 11/10/21 7:16 PM, Eric Auger wrote:
    > On 8/15/21 2:13 AM, Gavin Shan wrote:
    >> This supports SDEI_EVENT_CONTEXT hypercall. It's used by the guest
    >> to retrieved the original registers (R0 - R17) in its SDEI event
    >> handler. Those registers can be corrupted during the SDEI event
    >> delivery.
    >>
    >> Signed-off-by: Gavin Shan <gshan@redhat.com>
    >> ---
    >> arch/arm64/kvm/sdei.c | 40 ++++++++++++++++++++++++++++++++++++++++
    >> 1 file changed, 40 insertions(+)
    >>
    >> diff --git a/arch/arm64/kvm/sdei.c b/arch/arm64/kvm/sdei.c
    >> index b022ce0a202b..b4162efda470 100644
    >> --- a/arch/arm64/kvm/sdei.c
    >> +++ b/arch/arm64/kvm/sdei.c
    >> @@ -270,6 +270,44 @@ static unsigned long kvm_sdei_hypercall_enable(struct kvm_vcpu *vcpu,
    >> return ret;
    >> }
    >>
    >> +static unsigned long kvm_sdei_hypercall_context(struct kvm_vcpu *vcpu)
    >> +{
    >> + struct kvm *kvm = vcpu->kvm;
    >> + struct kvm_sdei_kvm *ksdei = kvm->arch.sdei;
    >> + struct kvm_sdei_vcpu *vsdei = vcpu->arch.sdei;
    >> + struct kvm_sdei_vcpu_regs *regs;
    >> + unsigned long index = smccc_get_arg1(vcpu);
    > s/index/param_id to match the spec?

    Sure, but "reg_id" seems better here. As the parameter indicates the GPR index
    to be fetched on request of the guest kernel.

    >> + unsigned long ret = SDEI_SUCCESS;
    >> +
    >> + /* Sanity check */
    >> + if (!(ksdei && vsdei)) {
    >> + ret = SDEI_NOT_SUPPORTED;
    >> + goto out;
    >> + }
    >> +
    >> + if (index > ARRAY_SIZE(vsdei->state.critical_regs.regs)) {
    >> + ret = SDEI_INVALID_PARAMETERS;
    >> + goto out;
    >> + }
    > I would move the above after regs = and use regs there (although the
    > regs ARRAY_SIZE of both is identifical)

    Ok.

    >> +
    >> + /* Check if the pending event exists */
    >> + spin_lock(&vsdei->lock);
    >> + if (!(vsdei->critical_event || vsdei->normal_event)) {
    >> + ret = SDEI_DENIED;
    >> + goto unlock;
    >> + }
    >> +
    >> + /* Fetch the requested register */
    >> + regs = vsdei->critical_event ? &vsdei->state.critical_regs :
    >> + &vsdei->state.normal_regs;
    >> + ret = regs->regs[index];
    >> +
    >> +unlock:
    >> + spin_unlock(&vsdei->lock);
    >> +out:
    >> + return ret;
    >> +}
    >> +
    >> int kvm_sdei_hypercall(struct kvm_vcpu *vcpu)
    >> {
    >> u32 func = smccc_get_function(vcpu);
    >> @@ -290,6 +328,8 @@ int kvm_sdei_hypercall(struct kvm_vcpu *vcpu)
    >> ret = kvm_sdei_hypercall_enable(vcpu, false);
    >> break;
    >> case SDEI_1_0_FN_SDEI_EVENT_CONTEXT:
    >> + ret = kvm_sdei_hypercall_context(vcpu);
    >> + break;
    >> case SDEI_1_0_FN_SDEI_EVENT_COMPLETE:
    >> case SDEI_1_0_FN_SDEI_EVENT_COMPLETE_AND_RESUME:
    >> case SDEI_1_0_FN_SDEI_EVENT_UNREGISTER:
    >>

    Thanks,
    Gavin

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