1 // SPDX-License-Identifier: GPL-2.0 2 #include <linux/types.h> 3 #include <linux/crash_dump.h> 4 5 #include <xen/interface/xen.h> 6 #include <xen/hvm.h> 7 8 #include "mmu.h" 9 10 #ifdef CONFIG_PROC_VMCORE 11 /* 12 * This function is used in two contexts: 13 * - the kdump kernel has to check whether a pfn of the crashed kernel 14 * was a ballooned page. vmcore is using this function to decide 15 * whether to access a pfn of the crashed kernel. 16 * - the kexec kernel has to check whether a pfn was ballooned by the 17 * previous kernel. If the pfn is ballooned, handle it properly. 18 * Returns 0 if the pfn is not backed by a RAM page, the caller may 19 * handle the pfn special in this case. 20 */ 21 static int xen_oldmem_pfn_is_ram(unsigned long pfn) 22 { 23 struct xen_hvm_get_mem_type a = { 24 .domid = DOMID_SELF, 25 .pfn = pfn, 26 }; 27 int ram; 28 29 if (HYPERVISOR_hvm_op(HVMOP_get_mem_type, &a)) 30 return -ENXIO; 31 32 switch (a.mem_type) { 33 case HVMMEM_mmio_dm: 34 ram = 0; 35 break; 36 case HVMMEM_ram_rw: 37 case HVMMEM_ram_ro: 38 default: 39 ram = 1; 40 break; 41 } 42 43 return ram; 44 } 45 #endif 46 47 static void xen_hvm_exit_mmap(struct mm_struct *mm) 48 { 49 struct xen_hvm_pagetable_dying a; 50 int rc; 51 52 a.domid = DOMID_SELF; 53 a.gpa = __pa(mm->pgd); 54 rc = HYPERVISOR_hvm_op(HVMOP_pagetable_dying, &a); 55 WARN_ON_ONCE(rc < 0); 56 } 57 58 static int is_pagetable_dying_supported(void) 59 { 60 struct xen_hvm_pagetable_dying a; 61 int rc = 0; 62 63 a.domid = DOMID_SELF; 64 a.gpa = 0x00; 65 rc = HYPERVISOR_hvm_op(HVMOP_pagetable_dying, &a); 66 if (rc < 0) { 67 printk(KERN_DEBUG "HVMOP_pagetable_dying not supported\n"); 68 return 0; 69 } 70 return 1; 71 } 72 73 void __init xen_hvm_init_mmu_ops(void) 74 { 75 if (is_pagetable_dying_supported()) 76 pv_mmu_ops.exit_mmap = xen_hvm_exit_mmap; 77 #ifdef CONFIG_PROC_VMCORE 78 register_oldmem_pfn_is_ram(&xen_oldmem_pfn_is_ram); 79 #endif 80 } 81