linux-stable/arch/x86/xen/mmu_hvm.c
David Hildenbrand cc5f2704c9 proc/vmcore: convert oldmem_pfn_is_ram callback to more generic vmcore callbacks
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>
2021-11-09 10:02:48 -08:00

69 lines
1.6 KiB
C

// SPDX-License-Identifier: GPL-2.0
#include <linux/types.h>
#include <linux/crash_dump.h>
#include <xen/interface/xen.h>
#include <xen/hvm.h>
#include "mmu.h"
#ifdef CONFIG_PROC_VMCORE
/*
* The kdump kernel has to check whether a pfn of the crashed kernel
* was a ballooned page. vmcore is using this function to decide
* whether to access a pfn of the crashed kernel.
* Returns "false" if the pfn is not backed by a RAM page, the caller may
* handle the pfn special in this case.
*/
static bool xen_vmcore_pfn_is_ram(struct vmcore_cb *cb, unsigned long pfn)
{
struct xen_hvm_get_mem_type a = {
.domid = DOMID_SELF,
.pfn = pfn,
};
if (HYPERVISOR_hvm_op(HVMOP_get_mem_type, &a)) {
pr_warn_once("Unexpected HVMOP_get_mem_type failure\n");
return true;
}
return a.mem_type != HVMMEM_mmio_dm;
}
static struct vmcore_cb xen_vmcore_cb = {
.pfn_is_ram = xen_vmcore_pfn_is_ram,
};
#endif
static void xen_hvm_exit_mmap(struct mm_struct *mm)
{
struct xen_hvm_pagetable_dying a;
int rc;
a.domid = DOMID_SELF;
a.gpa = __pa(mm->pgd);
rc = HYPERVISOR_hvm_op(HVMOP_pagetable_dying, &a);
WARN_ON_ONCE(rc < 0);
}
static int is_pagetable_dying_supported(void)
{
struct xen_hvm_pagetable_dying a;
int rc = 0;
a.domid = DOMID_SELF;
a.gpa = 0x00;
rc = HYPERVISOR_hvm_op(HVMOP_pagetable_dying, &a);
if (rc < 0) {
printk(KERN_DEBUG "HVMOP_pagetable_dying not supported\n");
return 0;
}
return 1;
}
void __init xen_hvm_init_mmu_ops(void)
{
if (is_pagetable_dying_supported())
pv_ops.mmu.exit_mmap = xen_hvm_exit_mmap;
#ifdef CONFIG_PROC_VMCORE
register_vmcore_cb(&xen_vmcore_cb);
#endif
}