// SPDX-License-Identifier: GPL-2.0
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#include <linux/types.h>
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#include <linux/crash_dump.h>
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#include <xen/interface/xen.h>
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#include <xen/hvm.h>
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#include "mmu.h"
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#ifdef CONFIG_PROC_VMCORE
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/*
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* This function is used in two contexts:
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* - the kdump kernel has to check whether a pfn of the crashed kernel
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* was a ballooned page. vmcore is using this function to decide
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* whether to access a pfn of the crashed kernel.
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* - the kexec kernel has to check whether a pfn was ballooned by the
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* previous kernel. If the pfn is ballooned, handle it properly.
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* Returns 0 if the pfn is not backed by a RAM page, the caller may
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* handle the pfn special in this case.
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*/
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static int xen_oldmem_pfn_is_ram(unsigned long pfn)
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{
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struct xen_hvm_get_mem_type a = {
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.domid = DOMID_SELF,
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.pfn = pfn,
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};
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int ram;
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if (HYPERVISOR_hvm_op(HVMOP_get_mem_type, &a))
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return -ENXIO;
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switch (a.mem_type) {
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case HVMMEM_mmio_dm:
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ram = 0;
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break;
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case HVMMEM_ram_rw:
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case HVMMEM_ram_ro:
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default:
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ram = 1;
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break;
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}
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return ram;
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}
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#endif
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static void xen_hvm_exit_mmap(struct mm_struct *mm)
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{
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struct xen_hvm_pagetable_dying a;
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int rc;
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a.domid = DOMID_SELF;
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a.gpa = __pa(mm->pgd);
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rc = HYPERVISOR_hvm_op(HVMOP_pagetable_dying, &a);
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WARN_ON_ONCE(rc < 0);
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}
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static int is_pagetable_dying_supported(void)
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{
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struct xen_hvm_pagetable_dying a;
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int rc = 0;
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a.domid = DOMID_SELF;
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a.gpa = 0x00;
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rc = HYPERVISOR_hvm_op(HVMOP_pagetable_dying, &a);
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if (rc < 0) {
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printk(KERN_DEBUG "HVMOP_pagetable_dying not supported\n");
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return 0;
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}
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return 1;
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}
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void __init xen_hvm_init_mmu_ops(void)
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{
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if (is_pagetable_dying_supported())
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pv_ops.mmu.exit_mmap = xen_hvm_exit_mmap;
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#ifdef CONFIG_PROC_VMCORE
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WARN_ON(register_oldmem_pfn_is_ram(&xen_oldmem_pfn_is_ram));
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#endif
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}
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