Re: [PATCH v11 6/7] x86/kvm/hyper-v: Add support for synthetic debugger via hypercalls
From: Roman Kagan <hidden>
Date: 2020-05-12 15:34:05
Also in:
kvm
Subsystem:
kernel virtual machine for x86 (kvm/x86), kvm x86 hyper-v (kvm/hyper-v), the rest, x86 architecture (32-bit and 64-bit) · Maintainers:
Sean Christopherson, Paolo Bonzini, Vitaly Kuznetsov, Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen
On Fri, Apr 24, 2020 at 02:37:45PM +0300, Jon Doron wrote:
quoted hunk ↗ jump to hunk
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. Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com> Signed-off-by: Jon Doron <redacted> --- arch/x86/kvm/hyperv.c | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+)diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c index 524b5466a515..744bcef88c70 100644 --- a/arch/x86/kvm/hyperv.c +++ b/arch/x86/kvm/hyperv.c@@ -1832,6 +1832,34 @@ 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->active) { + ret = HV_STATUS_INVALID_HYPERCALL_CODE; + break; + } + + 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; + }
I'd personally just push every hyperv hypercall not recognized by the kernel to userspace. Smth like this:
diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index bcefa9d4e57e..f0404df0f488 100644
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c@@ -1644,6 +1644,48 @@ int kvm_hv_hypercall(struct kvm_vcpu *vcpu) } kvm_vcpu_on_spin(vcpu, true); break; + case HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST: + if (unlikely(fast || !rep_cnt || rep_idx)) { + ret = HV_STATUS_INVALID_HYPERCALL_INPUT; + break; + } + ret = kvm_hv_flush_tlb(vcpu, ingpa, rep_cnt, false); + break; + case HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE: + if (unlikely(fast || rep)) { + ret = HV_STATUS_INVALID_HYPERCALL_INPUT; + break; + } + ret = kvm_hv_flush_tlb(vcpu, ingpa, rep_cnt, false); + break; + case HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST_EX: + if (unlikely(fast || !rep_cnt || rep_idx)) { + ret = HV_STATUS_INVALID_HYPERCALL_INPUT; + break; + } + ret = kvm_hv_flush_tlb(vcpu, ingpa, rep_cnt, true); + break; + case HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE_EX: + if (unlikely(fast || rep)) { + ret = HV_STATUS_INVALID_HYPERCALL_INPUT; + break; + } + ret = kvm_hv_flush_tlb(vcpu, ingpa, rep_cnt, true); + break; + case HVCALL_SEND_IPI: + if (unlikely(rep)) { + ret = HV_STATUS_INVALID_HYPERCALL_INPUT; + break; + } + ret = kvm_hv_send_ipi(vcpu, ingpa, outgpa, false, fast); + break; + case HVCALL_SEND_IPI_EX: + if (unlikely(fast || rep)) { + ret = HV_STATUS_INVALID_HYPERCALL_INPUT; + break; + } + ret = kvm_hv_send_ipi(vcpu, ingpa, outgpa, true, false); + break; case HVCALL_SIGNAL_EVENT: if (unlikely(rep)) { ret = HV_STATUS_INVALID_HYPERCALL_INPUT;
@@ -1653,12 +1695,8 @@ int kvm_hv_hypercall(struct kvm_vcpu *vcpu) if (ret != HV_STATUS_INVALID_PORT_ID) break; /* fall through - maybe userspace knows this conn_id. */ - case HVCALL_POST_MESSAGE: - /* don't bother userspace if it has no way to handle it */ - if (unlikely(rep || !vcpu_to_synic(vcpu)->active)) { - ret = HV_STATUS_INVALID_HYPERCALL_INPUT; - break; - } + default: + /* forward unrecognized hypercalls to userspace */ vcpu->run->exit_reason = KVM_EXIT_HYPERV; vcpu->run->hyperv.type = KVM_EXIT_HYPERV_HCALL; vcpu->run->hyperv.u.hcall.input = param;
@@ -1667,51 +1705,6 @@ int kvm_hv_hypercall(struct kvm_vcpu *vcpu) vcpu->arch.complete_userspace_io = kvm_hv_hypercall_complete_userspace; return 0; - case HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST: - if (unlikely(fast || !rep_cnt || rep_idx)) { - ret = HV_STATUS_INVALID_HYPERCALL_INPUT; - break; - } - ret = kvm_hv_flush_tlb(vcpu, ingpa, rep_cnt, false); - break; - case HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE: - if (unlikely(fast || rep)) { - ret = HV_STATUS_INVALID_HYPERCALL_INPUT; - break; - } - ret = kvm_hv_flush_tlb(vcpu, ingpa, rep_cnt, false); - break; - case HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST_EX: - if (unlikely(fast || !rep_cnt || rep_idx)) { - ret = HV_STATUS_INVALID_HYPERCALL_INPUT; - break; - } - ret = kvm_hv_flush_tlb(vcpu, ingpa, rep_cnt, true); - break; - case HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE_EX: - if (unlikely(fast || rep)) { - ret = HV_STATUS_INVALID_HYPERCALL_INPUT; - break; - } - ret = kvm_hv_flush_tlb(vcpu, ingpa, rep_cnt, true); - break; - case HVCALL_SEND_IPI: - if (unlikely(rep)) { - ret = HV_STATUS_INVALID_HYPERCALL_INPUT; - break; - } - ret = kvm_hv_send_ipi(vcpu, ingpa, outgpa, false, fast); - break; - case HVCALL_SEND_IPI_EX: - if (unlikely(fast || rep)) { - ret = HV_STATUS_INVALID_HYPERCALL_INPUT; - break; - } - ret = kvm_hv_send_ipi(vcpu, ingpa, outgpa, true, false); - break; - default: - ret = HV_STATUS_INVALID_HYPERCALL_CODE; - break; } return kvm_hv_hypercall_complete(vcpu, ret);
(would also need a kvm cap for that) Roman.