s390-ccw-virtio: allow for systems larger that 7.999TB
KVM does not allow memory regions > KVM_MEM_MAX_NR_PAGES, basically
limiting the memory per slot to 8TB-4k. As memory slots on s390/kvm must
be a multiple of 1MB we need start a new memory region if we cross
8TB-1M.
With that (and optimistic overcommitment in the kernel) I was able to
start a 24TB guest on a 1TB system.
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Message-Id: <20171211122146.162430-1-borntraeger@de.ibm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
[CH: 1UL -> 1ULL in KVM_MEM_MAX_NR_PAGES; build fix on 32 bit hosts]
Signed-off-by: Cornelia Huck <cohuck@redhat.com>
(cherry picked from commit bb223055b9
)
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
stable-2.11
parent
2ab0ce6e8d
commit
0f04a8bba6
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@ -152,14 +152,38 @@ static void virtio_ccw_register_hcalls(void)
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virtio_ccw_hcall_early_printk);
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}
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/*
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* KVM does only support memory slots up to KVM_MEM_MAX_NR_PAGES pages
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* as the dirty bitmap must be managed by bitops that take an int as
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* position indicator. If we have a guest beyond that we will split off
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* new subregions. The split must happen on a segment boundary (1MB).
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*/
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#define KVM_MEM_MAX_NR_PAGES ((1ULL << 31) - 1)
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#define SEG_MSK (~0xfffffULL)
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#define KVM_SLOT_MAX_BYTES ((KVM_MEM_MAX_NR_PAGES * TARGET_PAGE_SIZE) & SEG_MSK)
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static void s390_memory_init(ram_addr_t mem_size)
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{
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MemoryRegion *sysmem = get_system_memory();
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MemoryRegion *ram = g_new(MemoryRegion, 1);
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ram_addr_t chunk, offset = 0;
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unsigned int number = 0;
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gchar *name;
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/* allocate RAM for core */
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memory_region_allocate_system_memory(ram, NULL, "s390.ram", mem_size);
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memory_region_add_subregion(sysmem, 0, ram);
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name = g_strdup_printf("s390.ram");
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while (mem_size) {
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MemoryRegion *ram = g_new(MemoryRegion, 1);
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uint64_t size = mem_size;
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/* KVM does not allow memslots >= 8 TB */
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chunk = MIN(size, KVM_SLOT_MAX_BYTES);
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memory_region_allocate_system_memory(ram, NULL, name, chunk);
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memory_region_add_subregion(sysmem, offset, ram);
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mem_size -= chunk;
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offset += chunk;
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g_free(name);
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name = g_strdup_printf("s390.ram.%u", ++number);
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}
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g_free(name);
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/* Initialize storage key device */
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s390_skeys_init();
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