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From: Roman Kagan <rvkagan@yandex-team.ru>
To: Jon Doron <arilou@gmail.com>
Cc: kvm@vger.kernel.org, linux-hyperv@vger.kernel.org, vkuznets@redhat.com
Subject: Re: [PATCH v11 6/7] x86/kvm/hyper-v: Add support for synthetic debugger via hypercalls
Date: Tue, 12 May 2020 18:33:53 +0300	[thread overview]
Message-ID: <20200512153353.GB9944@rvkaganb.lan> (raw)
In-Reply-To: <20200424113746.3473563-7-arilou@gmail.com>

On Fri, Apr 24, 2020 at 02:37:45PM +0300, Jon Doron wrote:
> 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 <arilou@gmail.com>
> ---
>  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.

  reply	other threads:[~2020-05-12 15:34 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-24 11:37 [PATCH v11 0/7] x86/kvm/hyper-v: add support for synthetic debugger Jon Doron
2020-04-24 11:37 ` [PATCH v11 1/7] x86/kvm/hyper-v: Explicitly align hcall param for kvm_hyperv_exit Jon Doron
2020-05-13  8:42   ` Roman Kagan
2020-04-24 11:37 ` [PATCH v11 2/7] x86/kvm/hyper-v: Simplify addition for custom cpuid leafs Jon Doron
2020-05-13  9:24   ` Roman Kagan
2020-05-13 12:49     ` Jon Doron
2020-05-29 11:13       ` Paolo Bonzini
2020-04-24 11:37 ` [PATCH v11 3/7] x86/hyper-v: Add synthetic debugger definitions Jon Doron
2020-04-24 11:37 ` [PATCH v11 4/7] x86/kvm/hyper-v: Add support for synthetic debugger capability Jon Doron
2020-05-29 10:46   ` Paolo Bonzini
2020-05-29 12:08     ` Vitaly Kuznetsov
2020-05-29 12:17       ` Paolo Bonzini
2020-04-24 11:37 ` [PATCH v11 5/7] x86/kvm/hyper-v: enable hypercalls without hypercall page with syndbg Jon Doron
2020-05-13  9:57   ` Roman Kagan
2020-05-13 12:37     ` Jon Doron
2020-05-29 10:48   ` Paolo Bonzini
2020-04-24 11:37 ` [PATCH v11 6/7] x86/kvm/hyper-v: Add support for synthetic debugger via hypercalls Jon Doron
2020-05-12 15:33   ` Roman Kagan [this message]
2020-05-13 12:39     ` Jon Doron
2020-04-24 11:37 ` [PATCH v11 7/7] KVM: selftests: update hyperv_cpuid with SynDBG tests Jon Doron
2020-05-07  3:01 ` [PATCH v11 0/7] x86/kvm/hyper-v: add support for synthetic debugger Jon Doron
2020-05-07  7:57   ` Paolo Bonzini

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