static bool sev_es_validate_vmgexit()

in kvm/svm/sev.c [2356:2485]

• 112 lines of code
• 48 McCabe index (conditional complexity)

static bool sev_es_validate_vmgexit(struct vcpu_svm *svm)
{
	struct kvm_vcpu *vcpu;
	struct ghcb *ghcb;
	u64 exit_code;
	u64 reason;

	ghcb = svm->sev_es.ghcb;

	/*
	 * Retrieve the exit code now even though it may not be marked valid
	 * as it could help with debugging.
	 */
	exit_code = ghcb_get_sw_exit_code(ghcb);

	/* Only GHCB Usage code 0 is supported */
	if (ghcb->ghcb_usage) {
		reason = GHCB_ERR_INVALID_USAGE;
		goto vmgexit_err;
	}

	reason = GHCB_ERR_MISSING_INPUT;

	if (!ghcb_sw_exit_code_is_valid(ghcb) ||
	    !ghcb_sw_exit_info_1_is_valid(ghcb) ||
	    !ghcb_sw_exit_info_2_is_valid(ghcb))
		goto vmgexit_err;

	switch (ghcb_get_sw_exit_code(ghcb)) {
	case SVM_EXIT_READ_DR7:
		break;
	case SVM_EXIT_WRITE_DR7:
		if (!ghcb_rax_is_valid(ghcb))
			goto vmgexit_err;
		break;
	case SVM_EXIT_RDTSC:
		break;
	case SVM_EXIT_RDPMC:
		if (!ghcb_rcx_is_valid(ghcb))
			goto vmgexit_err;
		break;
	case SVM_EXIT_CPUID:
		if (!ghcb_rax_is_valid(ghcb) ||
		    !ghcb_rcx_is_valid(ghcb))
			goto vmgexit_err;
		if (ghcb_get_rax(ghcb) == 0xd)
			if (!ghcb_xcr0_is_valid(ghcb))
				goto vmgexit_err;
		break;
	case SVM_EXIT_INVD:
		break;
	case SVM_EXIT_IOIO:
		if (ghcb_get_sw_exit_info_1(ghcb) & SVM_IOIO_STR_MASK) {
			if (!ghcb_sw_scratch_is_valid(ghcb))
				goto vmgexit_err;
		} else {
			if (!(ghcb_get_sw_exit_info_1(ghcb) & SVM_IOIO_TYPE_MASK))
				if (!ghcb_rax_is_valid(ghcb))
					goto vmgexit_err;
		}
		break;
	case SVM_EXIT_MSR:
		if (!ghcb_rcx_is_valid(ghcb))
			goto vmgexit_err;
		if (ghcb_get_sw_exit_info_1(ghcb)) {
			if (!ghcb_rax_is_valid(ghcb) ||
			    !ghcb_rdx_is_valid(ghcb))
				goto vmgexit_err;
		}
		break;
	case SVM_EXIT_VMMCALL:
		if (!ghcb_rax_is_valid(ghcb) ||
		    !ghcb_cpl_is_valid(ghcb))
			goto vmgexit_err;
		break;
	case SVM_EXIT_RDTSCP:
		break;
	case SVM_EXIT_WBINVD:
		break;
	case SVM_EXIT_MONITOR:
		if (!ghcb_rax_is_valid(ghcb) ||
		    !ghcb_rcx_is_valid(ghcb) ||
		    !ghcb_rdx_is_valid(ghcb))
			goto vmgexit_err;
		break;
	case SVM_EXIT_MWAIT:
		if (!ghcb_rax_is_valid(ghcb) ||
		    !ghcb_rcx_is_valid(ghcb))
			goto vmgexit_err;
		break;
	case SVM_VMGEXIT_MMIO_READ:
	case SVM_VMGEXIT_MMIO_WRITE:
		if (!ghcb_sw_scratch_is_valid(ghcb))
			goto vmgexit_err;
		break;
	case SVM_VMGEXIT_NMI_COMPLETE:
	case SVM_VMGEXIT_AP_HLT_LOOP:
	case SVM_VMGEXIT_AP_JUMP_TABLE:
	case SVM_VMGEXIT_UNSUPPORTED_EVENT:
		break;
	default:
		reason = GHCB_ERR_INVALID_EVENT;
		goto vmgexit_err;
	}

	return true;

vmgexit_err:
	vcpu = &svm->vcpu;

	if (reason == GHCB_ERR_INVALID_USAGE) {
		vcpu_unimpl(vcpu, "vmgexit: ghcb usage %#x is not valid\n",
			    ghcb->ghcb_usage);
	} else if (reason == GHCB_ERR_INVALID_EVENT) {
		vcpu_unimpl(vcpu, "vmgexit: exit code %#llx is not valid\n",
			    exit_code);
	} else {
		vcpu_unimpl(vcpu, "vmgexit: exit code %#llx input is not valid\n",
			    exit_code);
		dump_ghcb(svm);
	}

	/* Clear the valid entries fields */
	memset(ghcb->save.valid_bitmap, 0, sizeof(ghcb->save.valid_bitmap));

	ghcb_set_sw_exit_info_1(ghcb, 2);
	ghcb_set_sw_exit_info_2(ghcb, reason);

	return false;
}