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virtio-mem: support CONFIG_PROC_VMCORE_DEVICE_RAM

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Let's implement the get_device_ram() vmcore callback, so
architectures that select NEED_PROC_VMCORE_NEED_DEVICE_RAM, like s390
soon, can include that memory in a crash dump.

Merge ranges, and process ranges that might contain a mixture of plugged
and unplugged, to reduce the total number of ranges.

Signed-off-by: David Hildenbrand <david@redhat.com>
Message-Id: <20241204125444.1734652-12-david@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
David Hildenbrand 2024-12-04 13:54:42 +01:00 committed by Michael S. Tsirkin
parent fe1d79dc54
commit c6a8239a9e
2 changed files with 89 additions and 0 deletions
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88
drivers/virtio/virtio_mem.c
View File

@ -2728,6 +2728,91 @@ static bool virtio_mem_vmcore_pfn_is_ram(struct vmcore_cb *cb,
mutex_unlock(&vm->hotplug_mutex);
return is_ram;
}
#ifdef CONFIG_PROC_VMCORE_DEVICE_RAM
static int virtio_mem_vmcore_add_device_ram(struct virtio_mem *vm,
struct list_head *list, uint64_t start, uint64_t end)
{
int rc;
rc = vmcore_alloc_add_range(list, start, end - start);
if (rc)
dev_err(&vm->vdev->dev,
"Error adding device RAM range: %d\n", rc);
return rc;
}
static int virtio_mem_vmcore_get_device_ram(struct vmcore_cb *cb,
struct list_head *list)
{
struct virtio_mem *vm = container_of(cb, struct virtio_mem,
vmcore_cb);
const uint64_t device_start = vm->addr;
const uint64_t device_end = vm->addr + vm->usable_region_size;
uint64_t chunk_size, cur_start, cur_end, plugged_range_start = 0;
LIST_HEAD(tmp_list);
int rc;
if (!vm->plugged_size)
return 0;
/* Process memory sections, unless the device block size is bigger. */
chunk_size = max_t(uint64_t, PFN_PHYS(PAGES_PER_SECTION),
vm->device_block_size);
mutex_lock(&vm->hotplug_mutex);
/*
* We process larger chunks and indicate the complete chunk if any
* block in there is plugged. This reduces the number of pfn_is_ram()
* callbacks and mimic what is effectively being done when the old
* kernel would add complete memory sections/blocks to the elfcore hdr.
*/
cur_start = device_start;
for (cur_start = device_start; cur_start < device_end; cur_start = cur_end) {
cur_end = ALIGN_DOWN(cur_start + chunk_size, chunk_size);
cur_end = min_t(uint64_t, cur_end, device_end);
rc = virtio_mem_send_state_request(vm, cur_start,
cur_end - cur_start);
if (rc < 0) {
dev_err(&vm->vdev->dev,
"Error querying block states: %d\n", rc);
goto out;
} else if (rc != VIRTIO_MEM_STATE_UNPLUGGED) {
/* Merge ranges with plugged memory. */
if (!plugged_range_start)
plugged_range_start = cur_start;
continue;
}
/* Flush any plugged range. */
if (plugged_range_start) {
rc = virtio_mem_vmcore_add_device_ram(vm, &tmp_list,
plugged_range_start,
cur_start);
if (rc)
goto out;
plugged_range_start = 0;
}
}
/* Flush any plugged range. */
if (plugged_range_start)
rc = virtio_mem_vmcore_add_device_ram(vm, &tmp_list,
plugged_range_start,
cur_start);
out:
mutex_unlock(&vm->hotplug_mutex);
if (rc < 0) {
vmcore_free_ranges(&tmp_list);
return rc;
}
list_splice_tail(&tmp_list, list);
return 0;
}
#endif /* CONFIG_PROC_VMCORE_DEVICE_RAM */
#endif /* CONFIG_PROC_VMCORE */
static int virtio_mem_init_kdump(struct virtio_mem *vm)
@ -2737,6 +2822,9 @@ static int virtio_mem_init_kdump(struct virtio_mem *vm)
#ifdef CONFIG_PROC_VMCORE
dev_info(&vm->vdev->dev, "memory hot(un)plug disabled in kdump kernel\n");
vm->vmcore_cb.pfn_is_ram = virtio_mem_vmcore_pfn_is_ram;
#ifdef CONFIG_PROC_VMCORE_DEVICE_RAM
vm->vmcore_cb.get_device_ram = virtio_mem_vmcore_get_device_ram;
#endif /* CONFIG_PROC_VMCORE_DEVICE_RAM */
register_vmcore_cb(&vm->vmcore_cb);
return 0;
#else /* CONFIG_PROC_VMCORE */

1
fs/proc/Kconfig
View File

@ -67,6 +67,7 @@ config NEED_PROC_VMCORE_DEVICE_RAM
config PROC_VMCORE_DEVICE_RAM
def_bool y
depends on PROC_VMCORE && NEED_PROC_VMCORE_DEVICE_RAM
depends on VIRTIO_MEM
help
If the elfcore hdr is allocated and prepared by the dump kernel
("2nd kernel") instead of the crashed kernel, RAM provided by memory