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https://github.com/torvalds/linux
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cc5f2704c9
Let's support multiple registered callbacks, making sure that registering vmcore callbacks cannot fail. Make the callback return a bool instead of an int, handling how to deal with errors internally. Drop unused HAVE_OLDMEM_PFN_IS_RAM. We soon want to make use of this infrastructure from other drivers: virtio-mem, registering one callback for each virtio-mem device, to prevent reading unplugged virtio-mem memory. Handle it via a generic vmcore_cb structure, prepared for future extensions: for example, once we support virtio-mem on s390x where the vmcore is completely constructed in the second kernel, we want to detect and add plugged virtio-mem memory ranges to the vmcore in order for them to get dumped properly. Handle corner cases that are unexpected and shouldn't happen in sane setups: registering a callback after the vmcore has already been opened (warn only) and unregistering a callback after the vmcore has already been opened (warn and essentially read only zeroes from that point on). Link: https://lkml.kernel.org/r/20211005121430.30136-6-david@redhat.com Signed-off-by: David Hildenbrand <david@redhat.com> Cc: Baoquan He <bhe@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Dave Young <dyoung@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jason Wang <jasowang@redhat.com> Cc: Juergen Gross <jgross@suse.com> Cc: "Michael S. Tsirkin" <mst@redhat.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Mike Rapoport <rppt@kernel.org> Cc: Oscar Salvador <osalvador@suse.de> Cc: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com> Cc: Stefano Stabellini <sstabellini@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
70 lines
1.6 KiB
C
70 lines
1.6 KiB
C
// 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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* 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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* Returns "false" 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 bool xen_vmcore_pfn_is_ram(struct vmcore_cb *cb, 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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if (HYPERVISOR_hvm_op(HVMOP_get_mem_type, &a)) {
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pr_warn_once("Unexpected HVMOP_get_mem_type failure\n");
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return true;
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}
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return a.mem_type != HVMMEM_mmio_dm;
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}
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static struct vmcore_cb xen_vmcore_cb = {
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.pfn_is_ram = xen_vmcore_pfn_is_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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register_vmcore_cb(&xen_vmcore_cb);
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#endif
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}
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