1 // SPDX-License-Identifier: GPL-2.0-only 2 /****************************************************************************** 3 * features.c 4 * 5 * Xen feature flags. 6 * 7 * Copyright (c) 2006, Ian Campbell, XenSource Inc. 8 */ 9 #include <linux/types.h> 10 #include <linux/cache.h> 11 #include <linux/export.h> 12 #include <linux/printk.h> 13 14 #include <asm/xen/hypercall.h> 15 16 #include <xen/xen.h> 17 #include <xen/interface/xen.h> 18 #include <xen/interface/version.h> 19 #include <xen/features.h> 20 21 /* 22 * Linux kernel expects at least Xen 4.0. 23 * 24 * Assume some features to be available for that reason (depending on guest 25 * mode, of course). 26 */ 27 #define chk_required_feature(f) { \ 28 if (!xen_feature(f)) \ 29 panic("Xen: feature %s not available!\n", #f); \ 30 } 31 32 u8 xen_features[XENFEAT_NR_SUBMAPS * 32] __read_mostly; 33 EXPORT_SYMBOL_GPL(xen_features); 34 35 void xen_setup_features(void) 36 { 37 struct xen_feature_info fi; 38 int i, j; 39 40 for (i = 0; i < XENFEAT_NR_SUBMAPS; i++) { 41 fi.submap_idx = i; 42 if (HYPERVISOR_xen_version(XENVER_get_features, &fi) < 0) 43 break; 44 for (j = 0; j < 32; j++) 45 xen_features[i * 32 + j] = !!(fi.submap & 1U << j); 46 } 47 48 if (xen_pv_domain()) { 49 chk_required_feature(XENFEAT_mmu_pt_update_preserve_ad); 50 chk_required_feature(XENFEAT_gnttab_map_avail_bits); 51 } 52 } 53