[PATCH v4 5/5] x86/kvm/hyper-v: Add support for synthetic debugger via hypercalls

Jon Doron
2020-03-09T18:20:38Z

There is another mode for the synthetic debugger which uses hypercalls
to send/recv network data instead of the MSR interface.

This interface is much slower and less recommended since you might get
a lot of VMExits while KDVM polling for new packets to recv, rather
than simply checking the pending page to see if there is data avialble
and then request.

Signed-off-by: Jon Doron <arilou@gmail.com>
---
arch/x86/kvm/hyperv.c | 22 ++++++++++++++++++++++
1 file changed, 22 insertions(+)

diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index 917b10a637fc..4a77ff61658b 100644
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -1821,6 +1821,28 @@ int kvm_hv_hypercall(struct kvm_vcpu *vcpu)
}
ret = kvm_hv_send_ipi(vcpu, ingpa, outgpa, true, false);
break;
+ case HVCALL_POST_DEBUG_DATA:
+ case HVCALL_RETRIEVE_DEBUG_DATA:
+ if (unlikely(fast)) {
+ ret = HV_STATUS_INVALID_PARAMETER;
+ break;
+ }
+ /* fallthrough */
+ case HVCALL_RESET_DEBUG_SESSION: {
+ struct kvm_hv_syndbg *syndbg = vcpu_to_hv_syndbg(vcpu);
+ if (!(syndbg->options & HV_X64_SYNDBG_OPTION_USE_HCALLS)) {
+ ret = HV_STATUS_OPERATION_DENIED;
+ break;
+ }
+ vcpu->run->exit_reason = KVM_EXIT_HYPERV;
+ vcpu->run->hyperv.type = KVM_EXIT_HYPERV_HCALL;
+ vcpu->run->hyperv.u.hcall.input = param;
+ vcpu->run->hyperv.u.hcall.params[0] = ingpa;
+ vcpu->run->hyperv.u.hcall.params[1] = outgpa;
+ vcpu->arch.complete_userspace_io =
+ kvm_hv_hypercall_complete_userspace;
+ return 0;
+ }
default:
ret = HV_STATUS_INVALID_HYPERCALL_CODE;
break;
--
2.24.1